Browse Topic: Rotary engines
Mazda, the automaker with the longest and richest history of using the Wankel rotary engine announced that it resumed mass production of rotary engines for a new variant of the MX-30 compact crossover. Mazda provided little detail about the engine itself, which serves as a generator for the MX-30 e-SKYACTIV R-EV, a plug-in hybrid (PHEV) variant of the MX-30 crossover. Mazda hasn't used the unique powerplant for a production vehicle for more than a decade. The MX-30 e-SKYACTIV R-EV employs the rotary engine in a series-hybrid layout to generate electricity to replenish the vehicle's 17.8-kWh lithium-ion battery, which when fully charged, can provide up to 85 km (31 miles) of driving range on Europe's Worldwide Light Vehicle Test Procedure (WLTP) cycle. Gasoline from a 50-L (13.2-gal.) fuel tank supplies the rotary when its operation is required to provide electricity for extended-range driving. In a release, Mazda explained it “positioned it [the rotary engine] on the same axle as a
Today unmanned aerial vehicle applications are powered by Wankel rotary engines due to their high power-to-weight ratio and smooth operation. Most of modern propulsion units for unmanned aerial vehicles are designed to run on high volatile fuels such as aviation gasoline (AvGas). However, the refueling infrastructure in aviation is geared toward the most used aviation fuel, kerosene. This and other reasons, such as significantly lower price and easier fire protection regulations, lead to the desire to be able to operate these propulsion units with kerosene. Opposed to reciprocating engines, the low compression ratio of rotary engines prevents the implementation of compression ignition combustion processes. Therefore, the purpose of this paper is to discuss the operation of a spark-ignited rotary engine on different fuels. In detail, different qualities of kerosene as well as gasoline/kerosene blends are compared together. In this respect, a thermodynamic analysis of the individual
The present work investigates a means of controlling engine hydrocarbon startup and shutdown emissions in a Wankel engine which uses a novel rotor cooling method. Mechanically the engine employs a self-pressurizing air-cooled rotor system (SPARCS) configured to provide improved cooling versus a simple air-cooled rotor arrangement. The novelty of the SPARCS system is that it uses the fact that blowby past the sealing grid is inevitable in a Wankel engine as a means of increasing the density of the medium used for cooling the rotor. Unfortunately, the design also means that when the engine is shutdown, due to the overpressure within the engine core and the fact that fuel vapour and lubricating oil are to be found within it, unburned hydrocarbons can leak into the combustion chambers, and thence to the atmosphere via either or both of the intake and exhaust ports. As well as shutdown it also affects the startup process, where higher hydrocarbon emissions are caused due to the forced
Wankel rotary engines (REs) are often used for unmanned aerial vehicle (UAV) applications due to their excellent power-to-weight ratio and their smooth operation. Existing RE propulsion units are mainly designed to run on high-volatility fuels like aviation gasoline or regular gasoline. However, specific applications require a jet fuel or even multi-fuel capability. Due to their geometry, the low compression ratio (CR) of REs prevents the implementation of compression ignition (CI) combustion processes. While publications of modified spark-ignition engines that are able to run on low-volatile fuels are already few in number, publications of heavy-fuel spark-ignited (SI) REs can hardly be found at all. The purpose of this paper is as follows: The operation of a SI RE operated on kerosene is discussed. Accordingly, a thermodynamic analysis is carried out at warmed-up operation with kerosene. It is shown that sufficient performance and power output can be achieved on kerosene for full
In a previous study it was shown that a production vehicle employing a Wankel rotary engine, the Mazda RX-8, was easily capable of meeting much more modern hydrocarbon emissions than it had been certified for. It was contended that this was mainly due to its provision of zero port overlap through its adoption of side intake and exhaust ports. In that earlier work a preliminary investigation was conducted to gauge the impact of adopting a zero overlap approach in a peripherally-ported Wankel engine, with a significant reduction in performance and fuel economy being found. The present work builds on those initial studies by taking the engine from the vehicle and testing it on an engine dynamometer. The results show that the best fuel consumption of the engine is entirely in line with that of several proposed dedicated range extender engines, supporting the contention that the Wankel engine is an excellent candidate for that role. Also, continued 1-D modelling of the zero overlap
The growing need for a sustainable worldwide mobility is leading towards a paradigm shift in the automotive industry. The increasingly restrictive regulations on vehicle emissions are indeed driving all of the world-leading road vehicles manufacturers to redesign the concept of transportation by developing new propulsion solutions. To this aim, a gradual electrification strategy is being adopted, and several hybrid electric solutions, such as extended-range electric vehicles with reciprocating engines or fuel cells, already represent a valid alternative to conventional vehicles powered by fossil fuels. Despite their appealing features, these hybrid propulsion systems present some drawbacks, mainly related to their complex architecture, causing high overall dimensions, weight and costs, which pose some limitation in their use for small-size vehicles. In this context, the Wankel engine may bring significant advantages, since it is characterized by an extremely compact and light design
The current quest to reduce CO2 emissions combined to new technologies has sparked an interest in revisiting radically different engine configuration concepts, such as adiabatic and split-cycle engines. To achieve the full potential of both concepts, the combustion chamber must be sealed without lubricating oil. A promising approach that has yet remained elusive, is to lubricate the piston-liner interface with gases. This paper explores the concept of using non-contacting finger seals to seal piston engines combustion chambers. The finger seals, made of a gas-lubricated pad at the end of a flexible beam, are fixed on a rotating piston that uses the centrifugal force to close the piston-liner gap. A physics-based fluid-structure model is developed to predict finger displacements and sealing performances. The model shows that the radial displacement of the fingers naturally creates a convergent profile with the liner that generates sufficient aerodynamic pressure to maintain a micrometer
The paper first includes the main objective and boundary conditions for design and simulation of a multi fuel gas mixture system of a Wankel rotary engine. New regenerative fuels are more and more important for use in automotive propulsion and stationary applications of combustion engines. Due to the special design and operation of rotary engines there are opportunities for running these engines in future electric and hybrid applications with new designed liquids and gaseous fuels based on regenerative energy sources. Nevertheless, rotary engines have advantages in avoidance of preignition and detonation especially when using gaseous fuels with a higher percentage of hydrogen. The focus is on basic research and analyses of main physical and thermodynamic properties of separate lean burn gases (lower calorific value, mixed calorific value, AFR) and their effects on fuel mixing and engine performance. Furthermore, the scope of the investigation is on the development of simulation models
The use of Wankel rotary engines as a range extender has been recognised as an appealing method to enhance the performance of Hybrid Electric Vehicles (HEV). They are effective alternatives to conventional reciprocating piston engines due to their considerable merits such as lightness, compactness, and higher power-to-weight ratio. However, further improvements on Wankel engines in terms of fuel economy and emissions are still needed. The objective of this work is to investigate the engine modelling methodology that is particularly suitable for the theoretical studies on Wankel engine dynamics and new control development. In this paper, control-oriented models are developed for a 225CS Wankel rotary engine produced by Advanced Innovative Engineering (AIE) UK Ltd. Through a synthesis approach that involves State Space (SS) principles and the artificial Neural Networks (NN), the Wankel engine models are derived by leveraging both first-principle knowledge and engine test data. We first
Currently automotive engines are reciprocating or Wankel rotary engine types. Reciprocating engines are bulky, heavy and complex, mainly due to the intake and exhaust valves and their associated cam-train. Wankel engines have a low rotor rev limit, and have inefficient sealing of the apex seals leading to poor economy and undesirable emission gases. The Rotary Engine Development Agency (REDA) has designed a new three-chamber rotary internal combustion engine concept using an adaptation of the patented Szorenyi Curve. The new design is an evolution of the design which was the subject of SAE Technical Paper 2017-01-2413 and SAE publication ‘So You Want to Design Engines: UAV Propulsion Systems’. This paper describes the features of the new three-chamber engine concept and includes an analysis of the major shortcomings of the Wankel engine. The Wankel engine’s geometry results in excessive crankshaft deflection at high engine revs due to the centrifugal force of the rotor which is
The intent of the specification is to present a functional set of requirements which define the user and hardware interfaces while providing sufficient capability to meet the misfire patterns for compliance demonstration and engineering development. Throughout this requirement, any reference to “ignition or injector control signal” is used interchangeably to infer that the effected spark ignition engine’s ignition control signal or the compression ignition engine’s injector control signal is interrupted, timing phased, or directly passed by the misfire generator. For spark ignition engines, the misfire generator behaves as a spark-defeat device which induces misfires by inhibiting normal ignition coil discharge. It does so by monitoring the vehicle’s ignition timing signals and suspends ignition coil saturation for selected cylinder firing events. The misfire generator will thereby induce engine misfire in spark ignited gasoline internal combustion engines; including rotary engines
The present work presents the concept of a new rotary engine, and provides first investigations for its implementation in the energy sector. The main focus of this work is to provide a theoretical description of the engine and its differences from the state-of-the-art technologies. Its innovative principle consists of concentric operation, with two pistons of different rotation radius and the addition of a third intermediate chamber between the compression and combustion chamber. A description of the engine’s physical model is provided, followed by an analysis of the selected specific geometrical features. Additionally, a thermodynamic analysis clarifies the operational advantage compared to the existing cycles and, finally, a numerical investigation on the engine’s bulk performance is provided to quantify the anticipated results of the theoretical analysis. The theoretical description concludes that the new rotary engine is characterized by simple design with the minimum possible
VRDE has developed Wankel type rotary engine to achieve high power output & fuel efficiency for indigenization programme of UAVs. This engine is meeting all performance parameters needed for intended aerial vehicle. This paper describes the testing methodology followed by development engineers to prove the endurance and reliability of UAV engine for airworthiness certification. This paper gives the brief about testing carried out on the Wankel engine, failures faced during endurance testing and their rectification to enhance the life of the engine to achieve hundred test cycle mark. This paper also briefs about the test set up, endurance test cycles simulating the practical operating conditions
Energy independence and reduction in pollutant emissions are a center of interest for several researchers and car manufacturers. Renewable fuels have gained in popularity because of their sustainability and, in some cases, lower amounts of greenhouse gases. Moreover, energy diversification is also required by all countries. One possible solution is the use of biofuels such as ethanol, methanol, etc. These biofuels have been shown as good candidates as alternative fuels for vehicles because they are liquid and they have several physical and combustion properties similar to gasoline. Alcohols have also a higher octane number and oxygen content than gasoline. This allows the alcohol engines to have much higher compression ratios (CRs), and thus, better BTE (brake thermal efficiency). Brazilian car manufacturing industry has developed flexible-fuel vehicles, introduced in 2003, which became a commercial success. Flex fuel internal combustion engines (ICEs) can run on any proportion of
The demand for lighter, smaller, more efficient, and more powerful engines calls for a rethinking of the traditional internal combustion engine (ICE). This paper describes development progress of LiquidPiston's small rotary engine, the XMv3, which operates on a Spark-Ignited (SI) variant of its patented High Efficiency Hybrid Cycle (HEHC). This thermodynamic cycle, which combines high compression ratio (CR), constant-volume combustion, and overexpansion, has a theoretical efficiency of up to 75 percent using air-standard assumptions and first-law analysis. XMv3 displaces 70cc (23cc per each of three working chambers) and is gasoline fueled. The engine is simple, having only two primary moving parts, which are balanced to prevent vibration. The ‘X’ engine geometry utilized by XMv3 can be considered an inverted ‘Wankel’, retaining the traditional Wankel' rotary advantages of high power density and smooth operation, while also overcoming some of Wankel's inherent performance limitations
Combustion behavior in Rotary Engine (RE) is quite different from that in conventional reciprocating engines. Therefore, it is important to observe the combustion in RE. In the previous studies, an optical RE was developed, which enabled the observation of the flame propagation in the rotor rotating direction (side view). In the present study, modification was made to the optical RE so that the observation of the flame propagation in the rotor width direction (bottom view) became possible. By using two high-speed cameras, the combustion in RE was observed by bottom view and side view simultaneously. Consequently, it was found that the flame propagation in the rotor width direction is also important for better engine performance as well as that in the rotor rotating direction
The Wankel rotary engine is more compact than conventional piston engines, but its oil and fuel consumption must be reduced to satisfy emission standards and customer expectations. A key step toward this goal is to develop a better understanding of the apex seal lubrication to reduce oil injection while reducing friction and maintaining adequate wear. This paper presents an apex seal dynamics model capable of estimating relative wear and predicting friction, by modeling the gas and oil flows at the seal interfaces with the rotor housing and groove flanks. Model predictions show that a thin oil film can reduce wear and friction, but to a limited extent as the apex seal running face profile is sharp due to the engine kinematics. The seal-housing interface remains between the boundary and mixed lubrication regimes, which leads to large asperity contact pressure and therefore significant wear of the running face, and an effective friction coefficient that varies between 0.03 to 0.11
This paper describes the development of a comprehensive simulation environment for investigations of gas-dynamic processes and combustion phenomena in rotary engines, conducted by the Austrian Institute for Powertrains and Automotive Technology of the Vienna University of Technology. In this connection, proven, commercially available engine cycle calculation Software-Tools have been used. For this, a rotary engine test bench has been established. As analysis tools, in addition to the traditional acquisition of the emitted engine torque, various pressures and temperatures, the recording of the pressure profile (combustion analysis measurement system) in the combustion chamber, as well as in the intake and exhaust ports, were used. The data of the test bench were used to develop and validate the methodology for the simulation tools. The focus in this paper is the development of a CFD (computational fluid dynamics) model with the software Converge from Convergent Science, Inc. In close
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