Browse Topic: Two stroke engines

Items (1,042)

Effect of Ignition Condition and Fuel Octane Number on Knock Intensity in a Small 2-Stroke Engine

2025-01-0211To be published on 06/16/2025

The internal combustion engines are widely used on automotive transportation for its high energy storage system efficiency and economic benefits. The 4-stroke engine has dominated all other forms to date, because the Otto cycle is simpler to comprehend. However, the significant benefits such as, less pumping work and friction, lighter construction of 2-stroke engine, helped with applications which appreciate the simplicity and power density as well as meet the emission regulations. The disadvantages of the 2-stroke engine mainly caused by the lack of sufficient scavenging process, which limited its trapping efficiency. Also, the overlap of the intake and exhaust phases results in charge short-circuiting, more fuel consumption and high unburned hydrocarbon emissions. For the reason above, it is difficult for 2-stroke engines to realize stoichiometric combustion and unable to use three-way catalyst to control emissions. The residual exhaust gas in the cylinder makes the spark ignition

Liu, Jinru, Yamazaki, Yoshiaki, Otaki, Yusuke, Kato, Hayato, Yokota, Takumi, Iijima, Akira

Basic Investigation of Thermodynamic Effects on a Hydrogen Two-Stroke Engine

2024-32-0039

04/18/2025

The spark ignited two-stroke engine, as a cost-efficient power unit with low maintenance demand, is used millionfold for the propulsion of hand-held application, motorcycles, scooters, boats and others. The outstanding power to weight ratio is the key advantage for two-stroke engines. However, poor exhaust emissions, caused by high scavenge losses, especially on port controlled two-stroke engines, and a low efficiency are disadvantages of this combustion process. Under the aspect of increasing environment- and health awareness, the two-stroke technology driven with fossil resources, shows no future advantage. The anthropogenic climate change force for sustainable development of combustion engines whereby reduction of fuel consumption or usage of alternative fuels is an important factor. Best way of a decarbonization to fulfil future climate goals is the utilization of non-carbon fuels. In this field of fuels, hydrogen, with its high energy content and close inexhaustible availability

Yasuda, Terutaka, Oswald, Roland, Kirchberger, Roland

Enhancements in Hydrogen Low Pressure Injection on Small Two-Stroke Engines

2024-32-0047

04/18/2025

The use of small 2-stroke crankcase scavenged engines running on hydrogen is very attractive for low power rates, when low cost and compact dimensions are the fundamental design constraints. However, achieving optimal performance with hydrogen fuel presents challenges, including uneven air-fuel mixtures, fuel losses, and crankcase backfiring. This research focuses on a small 50cc 2-stroke loop-scavenged engine equipped with a patented Low-Pressure Direct Injection (LPDI) system, modified for hydrogen use. Experimental results demonstrate performance comparable to the gasoline counterpart, but further optimizations are needed. Consequently, CFD-3D simulations are employed to analyses the injection process and guide engine development. The numerical analysis focuses on a fixed operating condition: 6000 rpm, Wide Open Throttle (WOT), with a slightly lean mixture and injection pressure fixed at 5 bar. A numerical model of the entire engine is set up with the primary objective of improving

Caprioli, Stefano, Schoegl, Oliver, Oswald, Roland, Kirchberger, Roland, Mattarelli, Enrico, Rinaldini, Carlo Alberto

Research on Basic Characteristics of a Two-Stroke Opposed Piston Engine

2024-32-0112

04/18/2025

This study investigated the performance characteristics of a two-stroke opposed piston engine that is capable of constantly operating with high power output and high efficiency. An investigation was also made of the performance obtained by applying a pseudo uniflow condition as a measure against large hydrocarbon (HC) emissions owing to blow-by of unburned mixture, which is an issue of two-stroke engines. The test engine had a displacement of 127 cm3 and a bore and stroke of 48 x 70 mm. One-point and dual-point ignition systems were used, and regular gasoline was supplied as the test fuel using a carburetor-based fueling system. Experiments were conducted at engine speeds of 1500 and 3000 rpm at ignition timings of 45 deg. and 35 deg. before top dead center. The results showed that large quantities of HC emissions were emitted because stable combustion was not achieved. This revealed that a stronger uniflow condition must be applied as a countermeasure rather than a simple pseudo

Fukushima, Shumpei, Uehara, Ryota, Hayashi, Yoshiaki, Igarashi, Ryo, Tokita, Kazuho, Iijima, Akira

Achieving Ultra-Low NO _x and Meeting Full Useful Life Requirement for CARB 2027 NO _x and GHG 2027 Phase 2 CO ₂ Regulation w/Opposed Piston 2-Stroke Engine and a Conventional ATS

2025-01-8391

04/01/2025

Internal combustion engines are expected to continue to play an important on-going role in the future of transportation, particularly in long haul transit and off-road applications. Substantially reducing criteria emissions of heavy-duty (HD) commercial vehicle engines while also reducing fuel consumption is the quickest way to achieve more sustainable transportation. The opposed-piston (OP) engine developed by Achates Power has demonstrated the ability to meet the most stringent ultralow NOx emissions requirements using only a conventional, underfloor aftertreatment system, offering reduced cost, complexity and compliance risk compared to other diesel engines. This paper is focused on the measurement results of Achates Power heavy-duty engine achieving CARB proposed ultralow NOx emission for 2027 and 2031+ full useful life requirements while also meeting the EPA Greenhouse Gas (GHG) Phase 2 limits with a conventional aftertreatment system (ATS), which was aged to 435k, 600k and 800k

Kale, Vaibhav, Bako, Zoltan

Experimental Study on Combustion and Emission Characteristics of a Two-Stroke Engine applying PODE/Methanol Blends Direct Injection

2025-01-7112

01/31/2025

In order to realize the Paris Agreement, which aims to strengthen the global response to climate change, conventional internal combustion engines (ICE) need to contribute to reducing carbon emissions and improving thermal efficiency. More importantly, in the face of energy shortages, it is urgent to search for sustainable fuels. Poly-oxymethylene dimethyl ethers (PODE) and methanol are both regard as important low-carbon, alternative fuels due to their high oxygen content. Using PODE can overcome the characteristics of methanol as a low-reactivity fuel with a low cetane number and poor ignition properties. In this study, the combustion and emission characteristics of PODE/methanol blends were investigated in a two-stroke direct injection engine. Firstly, the performance of the engine under pure PODE (P100) and PODE/methanol blends (P50) was compared. The results show that at BMEP of 0.31 MPa and injection timing of -8°CA ATDE, P50 blends have lower CO2, CO, NOX and THC emissions than

Dong, Pengbo, Sun, Zhuohan, Wang, Qingyang, Wang, Yang, Cui, Jingchen, Zhang, Zhenxian, Long, Wuqiang

Lubricants for Two-Stroke-Cycle Gasoline Engines

J1510_202501 (Current)

01/21/2025

The information in this SAE Recommended Practice has been compiled by Technical Committee 1 (Engine Lubrication) of the SAE Fuels and Lubricants Division. The intent is to provide those concerned with the design and maintenance of two-stroke-cycle engines with a better understanding of the properties of two-stroke-cycle lubricants. Reference is also made to test procedures which may be used to measure the chemical and physical characteristics of these lubricants.

Fuels and Lubricants TC 1 Engine Lubrication

A Computational Study of Hydrogen Direct Injection Using a Pre-Chamber in an Opposed-Piston Engine

2024-01-3010

07/02/2024

Combustion characteristics of a hydrogen (H2) direct-injected (DI) pre-chamber (PC)-assisted opposed piston two-stroke (OP2S) engine are investigated by 3D computational fluid dynamics (CFD) simulations. The architecture of the OP2S engine has potential features for reducing wall heat losses, as the DI H2 jets are not directed towards the piston face. To overcome the high resistance to autoignition of H2, a PC technology was implemented in order to enhance the ignition of the mixture by the multiple hot reactive jets. To further investigate the interaction between the H2 plume and the chamber walls, three different piston bowl designs were evaluated and ranked based on a merit function. For the cases under study, the flat piston design was found to be most favorable (compared to the narrow and wide pistons) due to its reduced surface area for lower wall heat losses. The results also showcase that a co-optimization approach considering various parameters is an effective strategy to

Menaca, Rafael, Moreno Cabezas, Kevin, Shakeel, Mohammad Raghib, Vorraro, Giovanni, Turner, James W. G., Im, Hong G.

Application of MAN Loop Scavenging in a 125 cc Two-Stroke Racing Engine

SAE-PP-0039505/08/2024

The use of MAN-type loop scavenging port arrangements in a 125 cc two-stroke racing engi-ne is being investigated. These make it possible to provide larger cross-sections for the trans-fer ports, but at the expense of the exhaust port cross-section. The investigation is carried out using 1D calculations with GT-Suite. It is shown that significantly higher maximum outputs are possible in this way. However, this requires large exhaust widths, as otherwise the exhaust port is too small and the advantage of the larger transfer cross-section is overcompensated. Mixed forms between the original MAN loop scavenging and Schnürle loop scavenging can represent a good compromise. One open point is the quality of the scavenging. A study found in the literature on the use of MAN loop scavenging on a small engine shows significantly worse results than is known from large engines. There is still a need for further investigation here.

Eilts, Peter

Evaluating the Effects of an Electrically Assisted Turbocharger on Scavenging Control for an Opposed Piston Two Stroke (OP2S) Compression Ignition Engine

2024-01-2388

04/09/2024

Opposed piston two-stroke (OP2S) diesel engines have demonstrated a reduction in engine-out emissions and increased efficiency compared to conventional four-stroke diesel engines. Due to the higher stroke-to-bore ratio and the absence of a cylinder head, the heat transfer loss to the coolant is lower near ‘Top Dead Center.’ The selection and design of the air path is critical to realizing the benefits of the OP2S engine architecture. Like any two-stroke diesel engine, the scavenging process and the composition of the internal residuals are predominantly governed by the pressure differential between the intake and the exhaust ports. Without dedicated pumping strokes, the two-stroke engine architecture requires external devices to breathe. In the unique OP2S engine architecture studied in this work, the external pumping devices present in the air path include an electrically assisted turbocharger (EAT), an electrified EGR pump, and a back-pressure valve (BPv) located downstream of the

Bhatt, Ankur, Gandolfo, John, Huo, Ming, Gainey, Brian, Lawler, Benjamin

1D-3D CFD Investigations to Improve the Performance of Two-Stroke Camless Engine

2024-01-2686

04/09/2024

The transportation sector still depends on conventional engines in many countries as the alternative technologies are not mature enough to reduce carbon footprints in society. The four-stroke diesel engines, primarily used for heavy-duty applications, need either high intake boosting or a large bore to produce higher torque and power output. There is an alternative where a four-stroke engine operated in two-stroke mode with the help of a fully flexible variable valve actuation (VVA) system can achieve similar power density without raising the intake boosting or engine size. A fully flexible VVA is required to control the valve events (lift, timing, and durations) independently so that the four-stroke events can be completed in one cycle. In this study, 1D-3D CFD coupled simulations were performed to develop a gas exchange process for better air entrapment in the cylinder and evacuate the exhaust products simultaneously. The intake and exhaust valve closing timings were optimized based

Tripathy, Srinibas, Dahlander, Petter, Somhorst, Joop, Kuylenstierna, Claes

A Renewable-Fuel 60% Efficient Engine - Insights from the General Cycle Equation

SAE-PP-0037011/25/2023

The General Cycle is a thermodynamic cycle that includes all six steps common to engine cycles. Thus it includes other engine cycles as subsets, each of these lacking one or more of the steps. The General Cycle engine, outside the realm of more commonly known thermodynamic cycles, is best suited to attain highest efficiency. Essential strategies for attaining 60% efficiency in an internal combustion engine are: (1) optimize parameters in the General Cycle, (2) reduce friction and heat transfer losses, and (3) preserve combustion efficiency. Obtaining a practical 60% efficient engine is a struggle against engine cost and power density. Add to that the problem of using only a renewable fuel with the intent of satisfying three additional goals: (1) net-zero-carbon emissions, (2) compatible with existing infrastructure and fuel systems, and (3) able to replace all current fossil fuel use. These conditions will require the highest efficiency in order to satisfy market demand given a limited

Rogers, Ernie, Collett, Glen

ZERO-EMISSION INTERNAL COMBUSTION ENGINE

SAE-PP-0036811/17/2023

A new concept of internal combustion engine has been developed. The purpose is to have an engine that can burn hydrocarbon fuels without discharging any greenhouse gas or other harmful substances into the atmosphere. The new engine, the zero-emission engine, inducts no air from the environment. Instead, the engine exhaust gas, with added oxygen, is used in performance of the combustion cycle. Carbon dioxide, the main byproduct of combustion is captured, stored, and unloaded during refueling for further storage, sequestration, or recycling. The zero-emission engine displacement can be significantly smaller than in a conventional air-inducting engine of equal power, with a significantly higher power density. The engine is unthrottled and it can operate with a much higher compression ratio without an increase in the cylinder temperature. The above concept also envisions recycling the captured carbon dioxide by using it with water to produce hydrocarbon fuel and oxygen that can be supplied

Schechter, Michael, schechter, victor

Development of Supercharged Two-Stroke Engine with Intake and Exhaust Valve for Hybrid System

2023-01-1823

10/24/2023

The two-stroke engine has a small displacement and high output, and therefore saves space when the engine is installed in a vehicle. Thus, the application of two-stroke engines to HEVs is a very effective means of reducing vehicle weight and securing engine space. On the other hand, the unfired element increases in the exhaust gas with a two-stroke engine because the air-fuel mixture is blown through to the exhaust system during the scavenging process inside the cylinder. Moreover, combustion becomes unstable due to the large amount of residual burnt gas in the cylinder. To solve these problems, we propose a two-stroke engine that has intake and exhaust valves that injects fuel directly into the cylinder. We describe the engine shape and the method that can provide high scavenging efficiency and stable combustion in such a two-stroke engine.

Hisano, Atsushi, Saitou, Masahito, Sakurai, Yota, Matsuda, Yoshimoto, ichi, Satoaki

On the Effects of Piston Pocket, Intake Port, and Transfer Duct Geometries in a Small Stratified-Scavenging Two-Stroke Engine

2023-01-1825

10/24/2023

The regulatory framework of pollutant emissions concerning non-road small internal combustion engines is becoming increasingly challenging. The upcoming scenario threatens to cut out small two-stroke engines because of the fuel short circuit occurring during transfer and exhaust ports overlap, causing the emission of unburned hydrocarbons and reducing engine efficiency. Despite this challenge, small two-stroke engines are unmatched in high power density applications in which weight and autonomy hinder the diffusion of electric technologies. The continuation of small two-stroke engines in the market will thus depend on the capability of mitigating fuel short circuit. From this perspective, some of the Authors found the low-pressure injection technology fulfilling the purpose at engine full load; however, in addition to system complexity and costs, a lack of mixture homogenization was noted at low load. Another solution concerns the adoption of a pocket milled in the piston skirt

Ciampolini, Marco, Raspanti, Sandro, Romani, Luca, Ferrara, Giovanni, Merolla, Santo, Gagliardi, Vincenzo

The Flathead Valved Boosted Uniflow Two Stroke Engine

2023-01-1826

10/24/2023

Experimental aviation engines face numerous challenges, including the need for energy efficiency, alternative fuel sources, reduced weight and size, greater durability with reliability, emissions reduction, and integration with advanced control and monitoring systems. This study presents the performance of a two-stroke engine with a Uniflow scavenging system with a flathead valve concept, with lower specific fuel consumption than conventional two-stroke aircraft engines. The engine’s maximum speed is limited to 3000 rpm for better cylinder scavenging efficiency, which also eliminates the need for a reduction gearbox, simplifies the design, and reduces the engine’s total mass. 1D simulations were conducted to evaluate combustion and performance parameters using aviation. At the maximum speed of 3000 rpm, the engine achieved a power of approximately 23 kW with boost around 3bar, while at cruise speeds between 2400 and 2700 rpm, the maximum torque is approximately 80 Nm, with specific

Hausen, Roberto Begnis, Martins, Mario, silveira, Juliano, Fagundez PhD, Jean Lucca

A Study of the Mechanism of High-Speed Knocking in a Two-Stroke SI Engine with High Compression Ratio

2023-01-1824

10/24/2023

Experimental methods and numerical analysis were used to investigate the mechanism of high-speed knocking that occurs in small two-stroke engines. The multi-ion probe method was used in the experiments to visualize flame propagation in the cylinder. The flame was detected by 14 ion probes grounded in the end gas region. A histogram was made of the order in which flames were detected. The characteristics of combustion in the cylinder were clarified by comparing warming up and after warming up and by extracting the features of the cycle in which knocking occurred. As a result, regions of fast flame propagation and regions prone to auto-ignition were identified. In the numerical analysis, flow and residual gas distribution in the cylinder, flame propagation and self-ignition were visualized by 3D CFD using 1D CFD calculation results as boundary conditions and initial conditions. Flame propagation calculated by 3D CFD was found to be directional due to in-cylinder flow caused by scavenging

Eto, Kuniyoshi, Kuboyama, Tatsuya, Moriyoshi, Yasuo, Yamada, Toshio, Yatsufusa, Tomoaki, Suzuki, Yusuke

Numerical Investigation of Knocking in a Small Two-Stroke Engine with a High Compression Ration to Improve Thermal Efficiency

2023-32-0079

09/29/2023

This study aimed to achieve both a high compression ratio and low knock intensity in a two-stroke engine. Previous research has suggested that knock intensity can be reduced by combining combustion chamber geometry and scavenging passaging design for the same engine specifications with a compression ratio of 13.7. In this report, we investigate whether low knock intensity can be achieved at compression ratios of 14.4 and 16.8 by adjusting the combustion chamber geometry and scavenging passage design. As a result, the mechanism by which combustion chamber geometry and scavenging passage design change knock intensity was clarified.

Eto, Kuniyoshi, Kuboyama, Tatsuya, Moriyoshi, Yasuo, Yamada, Toshio, Yamazaki, Takahiro, Yamaguchi, Shiro

Investigation of Liquid Lignin-Methanol Blends under Realistic Two-Stroke Marine Engines Conditions

2023-24-0085

08/28/2023

With a view to reducing the environmental impact of fossil fuels, advanced lignin-based biofuels could provide a valuable contribute, since lignin is the most abundant biopolymer on earth after cellulose. However, its thermophysical properties would hamper its use as a pure fuel. In this work we investigated the combustion behavior of sprays of a liquid lignin-methanol blend and evaluated its potential as a low-carbon marine fuel for large two-stroke engines. To this end, an experimental campaign was conducted in an optically accessible combustion chamber whose main dimensions correspond to those of a single cylinder for large two-stroke engines. The chamber is provided with optical accesses for optical diagnostics of the combustion process. The combustion of the mixture was ignited using a diesel pilot jet as the ignition source. Two marine injectors are mounted in the chamber, namely “main” and “pilot” injectors. The tests were performed in environmental conditions around 40 bar and

Lazzaro, Maurizio, Sementa, Paolo, Catapano, Francesco, Tornatore, Cinzia, Iannuzzi, Stefano, Boot, Michael, Kouris, Panos

High Performance and Near Zero Emissions 2-Stroke H ₂ Engine

2023-24-0068

08/28/2023

The paper presents a preliminary study on a virtual 2-stroke 3-cylinder 0.9 L DI SI supercharged engine running on Hydrogen (H2), able to meet both high performance targets and ultra-low emissions limits (NOx<20 ppm). Combustion is similar to a conventional 4-stroke H2 DI engine, while the design of the cylinder and the actuation law of both intake and exhaust valves are specifically optimized for the 2-stroke cycle. In comparison to a more conventional 2-stroke loop scavenged engine, with piston-controlled ports, the use of poppet valves enables a more flexible control of the gas exchange process and to maintain the same design of a 4-stroke engine for pistons, cylinders block, crankcase and lubrication system. On the other hand, it is more difficult to avoid the short-circuit of the fresh charge, while permeability of the valves becomes quite critical at high engine speed. Therefore, particular care was devoted to the optimization of the intake and exhaust ports geometry, as well as

Caprioli, Stefano, Volza, Antonello, Mattarelli, Enrico, Rinaldini, Carlo Alberto

A Case Study of an Integrated Starter Generator Failure and Benefits of Time Domain Torsional Vibration Analysis

2024-01-4125

08/10/2023

An Integrated Starter Generator (ISG) was integrated between an opposed piston two stroke engine and a 32 speed binary shift transmission for use in the Advanced Powertrain Demonstrator (APD). The initial design of the ISG integration and accompanying frequency domain torsional vibration analysis was performed considering driveline characteristics within the normal operating speed range of the engine. After a short period of time, the ISG suffered a catastrophic failure. The root cause of this failure is analyzed with special attention to the torsional behavior of the system. Multiple methods are employed to assess the torsional behavior including time domain torsional analysis. The time domain torsional analysis revealed that a significant number of torsional vibration cycles were occurring outside of the normal operating range of the engine as the engine accelerated from engine cranking speed to engine idle speed. The cycle accumulation during these short excursions through resonance

Srodawa, John

Investigation of In-Cylinder Pressure Measurement Methods within a Two-Stroke Spark Ignition Engine

01-17-01-0004

05/12/2023

This work describes an investigation of measurement techniques for the indicated mean effective pressure (IMEP) on a 55 cc single-cylinder, 4.4 kW, two-stroke, spark ignition (SI) engine intended for use on Group 1 and Group 2 remotely piloted aircraft (RPAs). Three different sensors were used: two piezoelectric pressure transducers (one flush mount and one measuring spark plug) for measuring in-cylinder pressure and one capacitive sensor for determining the top dead center (TDC) position of the piston. The effort consisted of three objectives: to investigate the merits of a flush mount pressure transducer compared to a pressure transducer integrated into the spark plug, to perform a parametric analysis to characterize the effect of the variability in the engine test bench controls on the IMEP, and to determine the thermodynamic loss angle for the engine. The results indicate that as a spark plug, the measuring spark plug is not statistically different from the stock spark plug at the

Ausserer, Joseph K., Polanka, Marc D., Litke, Paul J., Grinstead, Keith D.

Numerical Study on High-Load Performance of a Two-Stage Boosted Poppet-Valved Two-stroke Diesel Engine

2023-01-0443

04/11/2023

Two-stroke cycle is one of the most effective methods to increase the torque and power output of a four-stroke engine due to the doubled firing frequency compared to four-stroke cycle at the same engine speed. As the two-stroke cycle lacks separate intake and exhaust strokes, the positive pressure difference between intake and exhaust ports is required to drive fresh charge into the cylinder, and is affected by intake port structures due to the different amounts of short-circuited fresh charge during scavenging process. To evaluate the effects of intake port structures on the high-load performance of a boosted poppet-valved two-stroke diesel engine, one-dimensional gas dynamic model and three-dimensional computational fluid dynamics model were established and used to predict the high-load performance of the boosted two-stroke diesel engine with top-entry intake ports, inclined side-entry intake ports, and side-entry intake ports, respectively. The results show that the engine with

Fu, Xue-Qing, Zhang, Yan, Ding, Zhanming, Zhuang, Anbang, Zhu, Wei, Hou, Linlin, cheng, Jianghua, Zhang, Shuyong

Research of Spark Ignition Engine and Internal Mixture Formation Using Single-Zone, Two-Zone and Three-Zone Calculation Model of It Working Process

1325110/27/2022

Thermodynamic models based on the volume balance method for calculating the working process of an engine with spark ignition and internal mixture formation are presented. The single-zone model makes it possible to determine the pressure and average temperature of gases in the engine cylinder during the working process. The two-zone combustion model takes into account the change in the volume of the exhaust gases zone and the air-fuel mixture zone. The model makes it possible to determine the pressure of gases in the cylinder and the temperature in the zones under consideration when the air-fuel mixture is distributed over the entire above-piston volume at the moment of ignition. The three-zone combustion model takes into account the change in the volume of the exhaust gases zone, air-fuel mixture zones and air zones when organizing the stratification of the air-fuel charge, allows you to determine the gas pressure in the cylinder and the temperature in the zones under consideration

Korohodskyi, Volodymyr

Improving the Performance of Internal Combustion Engines and Reducing Emissions by Injecting Water with the Air Entering the Engines

04-16-01-0005

10/17/2022

The current work experimentally and theoretically studied the effect of water injection on improving the performance of three different types of single-cylinder internal combustion engines. The first engine is a four-stroke diesel, the second is a four-stroke gasoline, and the third is a two-stroke gasoline engine. Different amounts of water were injected relative to fuel consumption for the three engines to find how it affected the performance, exhaust gas temperatures, and emissions. Comparing the experimental and theoretical results was done to determine the effect of spraying water on lowering the temperatures of the exhaust gases, increasing the thermal efficiency, and lowering specific fuel consumption. The experimental results for the various tested engines show that, in general, the exhaust gas temperature and gas emission decreases by increasing the mass of water injection; these differences vary based on the engine and the operating conditions. Water injected at the inlet of

Hadidi, Haitham M., Hassan, Ahmed S. A.

Assessment of the Combustion Process in Ultra-Lean (λ>1.8) Natural Gas Engines

2022-01-1061

08/30/2022

The majority of today’s natural gas fired engines are applying a premixed combustion concept, which is commonly assumed to be based on the turbulence-enhanced propagation of a thin flame separating the burnt and unburnt fractions of the mixture volume. This concept has been confirmed by means of comprehensive experimental investigations on passenger car engines operating at air/fuel ratios close to stoichiometry; however, for larger industrial engines (4-stroke and 2-stroke) designed for ultra-lean (λ >1.8) operation in order to achieve highest efficiencies, this assumption is no longer valid, as will be shown in the following. On these engines, the combustion process is largely controlled by the reaction kinetics of the chemistry and hence exhibits more similarity to homogeneous charge or spark assisted compression ignition (HCCI or SACI) combustion concepts. This is substantiated by a detailed review on theoretical and experimental investigations of ultra-lean combustion processes, a

Unfug, Fridolin, Weisser, German Andreas

Research of Spark Ignition Engine and Internal Mixture Formation Using Single-Zone, Two-Zone and Three-Zone Calculation Model of It Working Process

2022-01-1000

08/30/2022

Korohodskyi, Volodymyr, Leontiev, Dmitry, Rogovyi, Andrii, Kryshtopa, Sviatoslav, Gritsuk, Igor, Voronkov, Oleksandr, Prokopiuk, Demian

An Investigation into the Effects of Swirl on the Performance and Emissions of an Opposed-Piston Two-Stroke Engine using Large Eddy Simulations

2022-01-1039

08/30/2022

Opposed-piston two-stroke (OP-2S) engines have the potential to achieve higher thermal efficiency than a conventional four-stroke diesel engine. However, the uniflow scavenging process is difficult to control over a wider range of speed and loads due to its sensitivity to pressure dynamics, port timings, and port design. Specifically, the angle of the intake ports can be used to generate swirl which has implications for open and closed cycle effects. This study proposes an analysis of the effects of port angle on the in-cylinder flow distribution and combustion performance of an OP-2S using computational fluid dynamics engine. Large Eddy Simulation (LES) was used to model turbulence given its ability to predict in-cylinder mixing and cyclic variability. A three-cylinder model was validated to experimental data collected by Achates Power and the grid was verified using an LES quality approach from the literature. The model was used to simulate port angles from 12 to 29 degrees at

O'Donnell, Patrick Christopher, Gainey, Brian, Vorwerk, Erik, Prucka, Robert, Lawler, Benjamin, Huo, Ming, Salvi, Ashwin

Effects of Port Angle on Scavenging of an Opposed Piston Two-Stroke Engine

2022-01-0590

03/29/2022

Opposed-piston 2-stroke (OP-2S) engines have the potential to achieve higher thermal efficiency than a typical diesel engine. However, the uniflow scavenging process is difficult to control over a wide range of speeds and loads. Scavenging performance is highly sensitive to pressure dynamics, port timings, and port design. This study proposes an analysis of the effects of port vane angle on the scavenging performance of an opposed-piston 2-stroke engine via simulation. A CFD model of a three-cylinder opposed-piston 2-stroke was developed and validated against experimental data collected by Achates Power Inc. One of the three cylinders was then isolated in a new model and simulated using cycle-averaged and cylinder-averaged initial/boundary conditions. This isolated cylinder model was used to efficiently sweep port angles from 12 degrees to 29 degrees at different pressure ratios. Results indicate that scavenging performance is correlated with the bulk swirl ratio generated by these

O'Donnell, Patrick Christopher, Gandolfo, John, Gainey, Brian, Vorwerk, Erik, Prucka, Robert, Filipi, Zoran, Lawler, Benjamin, Hessel, Randy, Kokjohn, Sage, Huo, Ming, Salvi, Ashwin

Usage of 2-Stroke Engines for Hybrid Vehicles

13-03-02-001103/24/2022

As the automotive industry moves toward electrification, battery costs and vehicle range are two large issues that will delay this movement. These issues can be partially resolved through the use of series-hybrid vehicles, which can replace a portion of the batteries with a small engine that serves to recharge the battery. Given the size, weight, and operational constraints of this engine, a 2-stroke engine makes sense. Indeed, 2-stroke engines are currently being used for a number of applications including consumer products, small ground vehicles, boats, and drones. The technology has significantly improved to allow for reduced emissions and increased efficiency, especially through the use of direct injection. This article discusses the state of technology for 2-stroke engines and its application in series-hybrid vehicles. In particular, the use of a 2-stroke engine as a range extender provides significant benefit in range and cost over fully electric vehicles. The study found that

Shah, Rajesh, Khan, Muqsit, Mittal, Vikram

E-Fuel applications in Non Road Mobile Machinery

2022-32-0074

01/09/2022

Professional users in particular will continue to rely on internal combustion engine drives in the future due to high power requirements and high daily energy consumption. Especially if they have to work in rural areas without the possibility of recharging batteries, such as in forestry or maintenance of road verges or railway lines. For these applications, it must be possible to run sustainable fuels for defossilization and drastically reduced CO2 emissions. This paper provides insights into a possible future fuel market and describes its evolution towards a more sustainable future from the perspective of a handheld equipment manufacturer. As developments in the fuel market are currently difficult to predict, manufacturers of hand-held power tools with combustion engines need to be prepared for changes in the composition of fuels that might become available on the market. This paper presents the engine performance results of both a 2-stroke engine and a 4-stroke engine, each with

von Gaertringen, Christoph Hiller, Schwerin, René, Schweiger, Stefan, Kölmel, Armin, Lochmann, Holger, Schmidt, Stephan, Zinner, Christian, Kirchberger, Roland, Gschanes, Dominik

Impact of Zero CO ₂ Fuels on Engine Behaviour of Two-Stroke Engines in Hand-Held Powertools

2022-32-0061

01/09/2022

One possible path to reduce the CO2 emissions of hand-held power tools are fuels with different amount of renewable content. Within this paper test bench measurements on a small two-stroke engine were carried out. We are trying to reduce CO2 emissions by using fuels which absorbed CO2 from the air during its lifetime or production, so called Zero CO2 fuels The focus was set on the investigation of combustion behaviour, performance and emissions of Zero CO2 fuels in comparison to commonly available fuels. For our measurements we chose a 46 cc serial engine, which was slightly modified for scientific research. This paper shows findings on effects of renewable fuels on engine characteristics. Additionally, the chemical properties of each fuel were investigated in order to form a comprehensive picture, together with the performed dyno measurements.

Gschanes, Dominik, Schmidt, Stephan, Kirchberger, Roland

On the Potential of Transfer Port Injection Strategies for a Two-Stroke Engine

2022-32-0057

01/09/2022

The main drawback of an in-cylinder Low Pressure Direct Injection (LPDI) in a two-stroke engine is the difficulty of achieving a satisfactory vaporization level in low load conditions. The liquid droplets are characterized by large diameters and, when the temperature level and the velocity of the scavenging flow field are low, the time needed for the droplet vaporization and the homogenization with fresh air becomes too long to guarantee a suitable mixture formation. A transfer port injection allows a higher flexibility, due to the possibility of performing a mixed injection either directly in the cylinder or indirectly in the crank case, depending on the load request or engine speed. Also, an even lower injection pressure can be adopted with respect to an in-cylinder LPDI injection, which is relevant in case of lightweight and low power applications. On the other hand, the time available for the direct in-cylinder injection is limited to the scavenge phase. In the present work, a

Balduzzi, Francesco, Romani, Luca, Ferrara, Giovanni, Trassi, Paolo, Fiaschi, Jacopo

Numerical Investigation of the Effect of Engine Speed and Delivery Ratio on the High-Speed Knock in a Small Two-Stroke SI Engine

2022-32-0080

01/09/2022

Knocking occurs within the high-speed range of small two-stroke engines used in handheld work equipment. High-speed knock may be affected by the engine speed and delivery ratio. However, evaluation of these factors independently using experimental methods is difficult. Therefore, in this study, these factors were independently evaluated using numerical calculations. The purpose of this study was to clarify the mechanism by which the intensity of high-speed knocking that occurs in small two-stroke engines becomes stronger. The results suggest that temperature inhomogeneity due to insufficient mixing of fresh air and previously burned gas may induce high-speed knocking in the operating range at high engine speeds.

Eto, Kuniyoshi, Kuboyama, Tatsuya, Moriyoshi, Yasuo, Yamada, Toshio

Study of Pre-chamber Jet Combustion Behavior using a Small Two-stroke Optically Accessible Engine

2022-32-0076

01/09/2022

A small 2-stroke engine can be an effective power source for an electric generator mounted on a series hybrid electric vehicle. In recent years, a technology referred to as pre-chamber jet combustion has attracted attention as a means of enhancing thermal efficiency by improving mixture ignitability. In this study, experiments were conducted to investigate differences in combustion behavior between the application of spark-ignited (SI) combustion and pre-chamber jet combustion to a small, two-stroke engine. The experimental equipment used was a two-stroke, single-cylinder, optically accessible engine with a displacement of 63.3 cm3. Differences between conventional SI combustion and pre-chamber jet combustion were examined by means of in-cylinder pressure analysis, in-cylinder combustion visualization and image processing software. The diameter of the connecting orifice of the pre-chamber was varied between two types. The results revealed that the combustion time and indicated mean

DEUSHI, Takato, NAKA, Takuma, TSUJIGUCHI, Tatsuya, IIJIMA, Akira, YAMAGUCHI, Shiro, KUROIWA, Minoru, ETO, Kuniyoshi

Increased Reliability and Usability through the Introduction of a User Interface Module for Hand-Held Small Engines

2022-32-0048

01/09/2022

Mobile hand-held or back-carried small engines must be weight-optimized due to their operability. At the same time there is enormous cost pressure within this market segment. Therefore, not all comfort and additional functions to increase user-friendliness can be adopted from the stationary applications. These include, for example, electric starting devices or additional sensors and actuators that take over advanced control processes to prevent or detect and report user or system errors. In the mobile small engine segment, this situation leads to the problem that the systems have many requirements for the user. These include, for example: physical ability to operate a pull starter know-how about the functioning of a combustion engine (2-stroke and 4-stroke) know-how for detecting failures and remedial actions If the knowledge about the behavior of engines is not given, or failures are overlooked, this automatically leads to a form of physical strain on the user due to the many

Öztürk, Bahattin, Stoffregen, Thorsten

Describing the Auto-Ignition Quality in Small, Air Cooled, Two Stroke Engines

2022-32-0063

01/09/2022

Auto-ignition quality is one of the most important properties in gasoline. Auto-ignition quality is today described by the Motor Octane Number (MON) and the Research Octane Number (RON). For modern, light duty, gasoline engines it has been quite well established that RON is the most accurate number. However, no study has been performed on hand held forest and garden products, such as chainsaws. Is the auto-ignition quality best described in the same way for these engines as for light duty engines? In this paper, a matrix of six different fuels with different combinations of MON and RON values were tested on a Husqvarna 550 XP Mark II, a modern air cooled, sequential stratified scavenging 2-stroke chainsaw engine. Ignition timing sweeps were performed and knock limited spark advance (KLSA) were calculated. Then the data has been analyzed with a multi-variate analysis of KLSA against both MON and RON to try to determine how MON and RON should be combined to best describe the anti-knock

Risberg, Per, Elm, Thomas, Bergman, Mikael, Hellquist, Fredrik, Karvo, Anna, Tripathi, Rupali

Design and Implementation of An Oxidation Catalyst for A Spark Ignited Two Stroke Snowmobile Engine

2022-32-0005

01/09/2022

The primary goal of this project was to design and implement an oxidation catalyst specific to a high-performance spark ignited two stroke engines to reduce vehicle-out emissions. The primary challenges of two stroke catalysis at high loads include controlling the catalytic reaction temperature as well as minimizing the increase in exhaust back pressure due to the addition of a catalyst. Reaction temperature is difficult to control due to high HC and CO concentrations paired with an excess of oxygen in the exhaust stream. By limiting catalyst conversion efficiency, the reaction temperatures were controlled. Two stroke engines are also inherently sensitive to changes in exhaust back pressure and therefore location and sizing of the catalyst are key design considerations. Because of these challenges significant effort was directed toward developing the two-stroke specific catalyst design process. Through these efforts several key outcomes were reached including a better understanding of

Squires, Noah, A. Miers, Scott

Thermodynamic Analysis of Novel 4-2 Stroke Opposed Piston Engine

2021-24-0096

09/05/2021

In this work, a novel opposed piston architecture is proposed where one crankshaft rotates at twice the speed of the other. This results in one piston creating a 2-stroke profile and another with a 4-stroke profile. In this configuration, the slower piston operates in the 2-stroke CAD domain, while the faster piston completes 2 reciprocating cycles in the same amount of time (4-stroke). The key benefit of this cycle is that the 4-stroke piston increases the rate of compression and expansion (dV/dθ), which lowers the combustion-induced pressure rise rate after top dead center (crank angle location of minimum volume). Additionally, it lowers in-cylinder temperatures and pressures more rapidly, resulting in a lower residence time at high temperatures, which reduces residence time for thermal NOx formation and reduces the temperature differential between the gas and the wall, thereby reducing heat transfer. In this work, a custom 0D thermodynamic model was used to study the sensitivity of

Moser, Sean, Gainey, Brian, Lawler, Benjamin, Filipi, Zoran

Simulation Study of a Turbocharged Two-Stroke Single Cylinder 425cc SI Engine

2021-24-0003

09/05/2021

An afterburner-assisted turbocharged single-cylinder 425 cc two-stroke SI-engine is described in this simulation study. This engine is intended as a Backup Range Extender (REX) application for heavy-duty battery electric vehicles (BEV) when external electric charging is unavailable. The 425 cc engine is an upscaled version of a 125 cc port-injected engine [26] which demonstrated that the selected technology could provide a specific power level of 400 kW/L and the desired 150 kW in a heavy duty BEV application. The 425 cc single cylinder two-stroke engine is an existing engine as one half of a 850 cc snowmobile engine. This simulation study includes upscaling of the swept volume, impact on engine speed and gas exchange properties. In the same way as for the 125cc engine [26], the exhaust gases reaches the turbine through a tuned exhaust pipe and an afterburner or oxidation catalyst. The intent with the afterburner is to convert some of the air and hydrocarbons (HC) to heat to provide

Zander, Lennarth

New4stroke Engine

SAE-PP-0011604/21/2021

You are the inventor of a new type of four-stroke engine. I graduated from the department of combustion engines at the Cracow University of Technology in 1979. I made the first prototype of such an engine for my own money, which worked well and encouraged me to further research. In 1982 I started to build a second prototype, which after it was completed with its research in 1985, surprised me with its qualities more than I expected. Here is the first basic description of this engine

Feliks, Andrew

Power and Torque Determination for UAS Engines Having Maximum Power Ratings at or Below 22.4 kW

ARP6971 (Current)

04/07/2021

This recommended practice is applicable to reciprocating engines powering unmanned aerial vehicles (UAV) having rated power values less than 22.4 kW, and which are not to be used for human transport.

null, null

Turbocompounding the Opposed-Piston 2-Stroke Engine

2021-01-0636

04/06/2021

This paper presents analytical research conducted into the level of fuel consumption improvement that can be expected from turbocompounding a medium-duty opposed-piston 2-stroke engine, which is part of a hybridized vehicle propulsion system. It draws on a successful earlier study which showed a non-compounded opposed-piston engine to be clearly superior to other forms of 2-stroke engine, such as the widely adopted uniflow-scavenged poppet valve configuration. Electrical power transmission is proposed as the method of providing the necessary variable-speed drive to transmit excess turbine power to the system energy storage medium. The work employs one-dimensional engine simulation on a single-cylinder basis, using brake specific fuel consumption (BSFC) as the reportable metric, coupled with positive or negative power flow to the engine from the compounder; this is a variation on an approach successfully used in earlier work. Here it shows the sensitivities of the overall system to

Young, Alexander, Turner, James, Head, Robert

Analysis of a Turbocharged Single-Cylinder Two-Stroke SI Engine Concept

2021-01-0642

04/06/2021

Power dense internal combustion engines (ICEs) are interesting candidates for onboard charging devices in different electric powertrain applications where the weight, volume and price of the energy storage components are critical. Single-cylinder naturally aspirated two-stroke spark-ignited (SI) engines are very small and power dense compared to four-stroke SI engines and the installation volume from a single cylinder two-stroke engine can become very interesting in some concepts. During charged conditions, four-stroke engines become more powerful than naturally aspirated two-stroke engines. The performance level of a two-stroke SI engines with a charging system is less well understood since only a limited number of articles have so far been published. However, if charging can be successfully applied to a two-stroke engine, it can become very power dense. This article outlines some of the challenges related to charging systems for a single-cylinder crank case scavenged two-stroke SI

Zander, Lennarth, Dahlander, Petter

Improvement of Working Parameters in Opposed Piston CI Two-Stroke Engines by Modelling Research

1262709/17/2020

Two-stroke opposed piston engines (2sOPEs) have great potential for industrial applications due to their simple design, technology and high efficiency, particularly with a turbocharging system. The paper presents possibilities for altering 2sOPE working parameters by changing geometrical parameters and boosting parameters. Obtaining higher engine efficiency is realised by altering the crank phase shift of the exhaust piston in relation to the transfer piston. It has been assumed that only the piston of the exhaust cylinder changes its position relative to the piston in the cylinder with transfer ports. Modifying the scavenging process by changing pistons? position through connecting with two crankshafts enables asymmetrical scavenging timing. Closing the exhaust ports before the compression process and extending the time allotted to empty exhaust gases from the cylinder provides greater engine work, and a high boost ratio increases engine power. This type of engine was recently

Mitianiec, Wladyslaw

Research of the Gas Fuel Supply Process on the Compression Stroke in Ship’s Low-Speed Gas-Diesel Engines

2020-01-2107

09/15/2020

In connection with the tightening of environmental standards, the leading manufacturers of marine low-speed engines are carrying out intensive work on their conversion to gas fuels. Due to the design features in this class of engines, only internal mixture formation is possible. For the organization of which two different approaches are possible. To date, only two are currently implemented. MAN started production of engines with gas fuel supply to the working cylinder under high pressure at the end of the compression stroke, and WinGD under low pressure at the beginning of the compression stroke. The analysis, performed by the authors, showed, that increasing the pressure before the gas supplying mechanisms to 3.5...6.0 MPa can reduce the residence time of the gas-air mixture in the working cylinder and reduce the likelihood of detonation combustion. The supply of gas fuel to the working cylinder with a changing back pressure significantly affects on the flow characteristics of the gas

Belousov, Evgen, Marchenko, Andrii, Gritsuk, Igor V., Savchuk, Volodymyr, Bulgakov, Nickolay, Mitienkova, Vira, Ahieiev, Maksym, Samarin, Oleksandr, Vrublevskyi, Roman, Volodarets, Mykyta, Kalashnikov, Yevhen, Pronin, Sergii

Improvement of Working Parameters in an Opposed Piston CI Two-Stroke Engine by Modelling Research

2020-01-2062

09/15/2020

Two-stroke opposed piston engines (2sOPEs) have great potential for industrial applications due to their simple design, technology and high efficiency, particularly with a turbocharging system. The paper presents possibilities for altering 2sOPE working parameters by changing geometrical parameters and boosting parameters. Obtaining higher engine efficiency is realised by altering the crank phase shift of the exhaust piston in relation to the transfer piston. It has been assumed that only the piston of the exhaust cylinder changes its position relative to the piston in the cylinder with transfer ports. Modifying the scavenging process by changing pistons’ position through connecting with two crankshafts enables asymmetrical scavenging timing. Closing the exhaust ports before the compression process and extending the time allotted to empty exhaust gases from the cylinder provides greater engine work, and a high boost ratio increases engine power. This type of engine was recently

Mitianiec, Wladyslaw

Optical Characterization of the Combustion Process inside a Large-Bore Dual-Fuel Two-Stroke Marine Engine by Using Multiple High-Speed Cameras

2020-01-0788

04/14/2020

Dual-fuel engines for marine propulsion are gaining in importance due to operational and environmental benefits. Here the combustion in a dual-fuel marine engine operating on diesel and natural gas, is studied using a multiple high-speed camera arrangement. By recording the natural flame emission from three different directions the flame position inside the engine cylinder can be spatially mapped and tracked in time. Through space carving a rough estimate of the three-dimensional (3D) flame contour can be obtained. From this contour, properties like flame length and height, as well as ignition locations can be extracted. The multi-camera imaging is applied to a dual-fuel marine two-stroke engine, with a bore diameter of 0.5 m and a stroke of 2.2 m. Both liquid and gaseous fuels are directly injected at high pressure, using separate injection systems. Optical access is obtained using borescope inserts, resulting in a minimum disturbance to the cylinder geometry. In this type of engine

Hult, Johan, Matamis, Alexios, Baudoin, Eric, Mayer, Stefan, Richter, Mattias

Pre-design Investigation of Resonant Frequency Effects on Gas Exchange Efficiencies of a One-kW Natural-Gas Linear Engine Alternator

2020-01-0488

04/14/2020

Performance of a natural gas two-stroke engine incorporated in a 1-kW free-piston oscillating Linear Engine Alternator (LEA) - a household electricity generator - was investigated under different resonant frequencies for pre-design phase purposes. To increase the robustness, power density, and thermal efficiencies, the crank mechanism in free-piston LEA is omitted and all moving parts of the generator operate at a fixed resonant frequency. Flexure springs are the main source of the LEA’s stiffness and the mass-spring dynamics dominates the engine’s speed. The trade-off between the engine’s performance, mass-spring system limits, and power and efficiency targets versus the LEA speed is very crucial and demands a careful investigation specifically at the concept design stages to find the optimum design parameters and operating conditions. CFD modeling was performed to analyze the effects of resonant frequency on the engine’s gas exchange behavior. To take combustion effects into account

Zamani Meymian, Nima, Darzi, Mahdi, Johnson, Derek, Famouri, Parviz

Numerical Simulation and Optimization for Combustion of an Opposed Piston Two-Stroke Engine for Unmanned Aerial Vehicle (UAV)

2020-01-0782

04/14/2020

An opposed piston two-stroke engine is more suitable for use in an unmanned aerial vehicle because of its small size, excellent self-balancing, stable operation, and low noise. Consequently, in this study, based on experimental data for a prototype opposed piston two-stroke engine, numerical simulation models were established using GT-POWER for 1D simulation and AVL-FIRE for 3D CFD simulation. The mesh grid and solver parameters for the numerical model of the CFD simulation were determined to guarantee the accuracy of the numerical simulation, before studying and optimizing the ventilation efficiency of the engine with different dip angles. Furthermore, the fuel spray and combustion were analyzed and optimized in details.

Zhou, Lei, Li, Hao, Chen, Zeyu, Zhao, Zhenfeng, Zhang, Fujun

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