Browse Topic: Fuel control
This SAE Aerospace Information Report (AIR) defines helicopter turboshaft engine power assurance theory and methods. Several inflight power assurance example procedures are presented. These procedures vary from a very simple method used on some normal category civil helicopters, to the more complex methods involving trend monitoring and rolling average techniques. The latter method can be used by small operators but is generally better suited to the larger operator with computerized maintenance record capability
This SAE Aerospace Recommended Practice describes a method for conducting room temperature, contaminated fuel, endurance testing when the applicable specification requires nonrecirculation of the contaminants. The objective of the test is to determine the resistance of engine fuel system components to wear or damage caused by contaminated fuel operation. It is not intended as a test for verification of the component's filter performance and service life. ARP1827 is recommended for filter performance evaluation
As competent and low-pollution alternative fuel, CNG has revealed its excellence over engine performance and emissions. In recent years, CNG is considered as the diesel engine alternative fuel for heavy-duty engine applications due to its lower emissions and cost effective after-treatment systems. Due to the implementation of stricter emission norms over the years, the evolution of the fuel supply system has become more robust and electronically controlled. In the case of CNG engines, most of the engines were equipped with MPFI fuel system, for its precise fuel control abilities and controlling emission parameters. However, this MPFI system encompasses severe design changes in the intake manifold and is cost worthy to OEMs over the SPFI fuel system. MPFI system adds on the overall cost of the engine unit and its maintenance when compared to SPFI system. SPFI fuel system had proved its robustness to achieve BSIV emission norms but, due to challenging test methods and stringent emission
A fuel level control valve/system controls the quantity of fuel in a tank being filled or emptied on the aircraft. This document provides a general familiarization with these mechanisms (e.g., forms they take, functions, system design considerations). This document provides the aircraft fuel system designer with information about these mechanisms/devices, so that he can prescribe the types of level control valves/systems which are best suited for his particular fuel system configuration. The scope has been expanded as different aircraft manufacturers may use different type of fuel system architectures. Their refueling and defueling systems may take different configurations, may require different types of fuel control valves and may require different types of interface with the onboard Fuel Measurement System. They must also limit pressure surges and be compatible with ground refueling equipment which have varying surge potentials and create surges
Ice formation in aircraft fuel systems results from the presence of dissolved and undissolved water in the fuel. Dissolved water or water in solution with hydrocarbon fuels constitutes a relatively small part of the total water potential in a particular system with the quantity dissolved being primarily dependent on the fuel temperature and the water solubility characteristics of the fuel. One condition of undissolved water is entrained water, such as water particles suspended in the fuel as a result of mechanical agitation of free water or conversion of dissolved water through temperature reduction. This can be considered as analogous to an emulsion state. Another condition of undissolved water is free water which may be introduced as a result of refueling or the settling of entrained water which collects at the bottom of a fuel tank in easily detectable quantities separated by a continuous interface from the fuel above. Water may also be introduced as a result of condensation from
This specification covers the requirements for format and outline of contents of operating instructions in published form or in manuscript form suitable for publication
As climate change drives the exploration into new and alternative fuels, biodiesel has emerged as a promising alternative to traditional diesel fuel. To further increase the viability of biodiesel, a unique system at the University of Kansas utilizes glycerin, the primary byproduct of biodiesel production, for power generation. This system converts glycerin into a hydrogen-rich gas (syngas) that is sent to an engine-generator system in one continuous flow process. The current setup allows for running the engine-generator system on pure propane, reformed propane, or reformed glycerin, with each fuel serving a unique purpose. This paper discusses upgrades in pure propane operation that serves the intent of preheating the engine prior to syngas operation and establishing the baseline energy requirement for fueling the system. The current upgrade to the fuel system incorporates an Electric Fuel Valve (EFV) as a replacement for a gaseous propane carburetor, providing the ability for Air-to
To meet US EPA light-duty vehicle emission standards, the vehicle powertrain has to be optimally controlled in addition to maintaining very high catalyst system efficiency. If vehicles are operated outside the bounds of a standard laboratory exhaust emission test (e.g., on-road or off-cycle) the operating control strategy may shift to optimize other desirable parameters such as fuel economy and drivability. Under these circumstances. The engine control system could be operating in a different state space from an emission control stand point. This control state-space can be observed based on four principal parameters: NOx, Lambda and exhaust temperature (measured at the tailpipe) and vehicle acceleration. These vehicle emission control patterns can be characterized by their corresponding emission control signatures, such as cold start, transient fuel control, and high speed/high load open loop. These emission control signatures are unique to a variety of engine technologies as well
This SAE Aerospace Information Report (AIR) is intended as a guide toward standardization of descriptions and specifications of fluid contamination products
Delphi Diesel Systems (DDS) - Heavy Duty Business is developing a new range of Ultra High Pressure Common Rail Fuel Injectors with the functionality to allow the combustion heat release to be heavily adapted during operation. This allows the injector performance to be simultaneously optimised across a broad range of engine conditions, removing the constraints of having to select a single rate shape type for all operating conditions. This new technology range builds on the performance of Delphi's 2700 bar Fuel Systems of F2E, F2P and F2R, whilst adding in new levels of injector control, beyond what is available in the current market. In addition to this new functionality, Delphi's new Heavy Duty Injector range also demonstrates greatly reduced leakage and improved accuracy of fuel control. This paper reviews the benefits and possibilities of this new injector technology
This paper discusses on-engine results achieved in applying an algorithm-based Individual Cylinder Fuel Control (ICFC) to turbocharged four-cylinder engines. ICFC is a software algorithm which permits the detection and closed-loop correction of air/fuel imbalances on a cylinder-by-cylinder basis, which is not possible with typical bank-wide closed loop fuel control systems. Cylinder-to-cylinder air/fuel imbalances can be the result of a number of combined sources. The potential sources include fuel injector variation (both new and aged) as well as maldistribution of fresh air airflow, evaporative emissions purge flow, or exhaust gas recirculation flow. The ICFC algorithm requires no additional hardware beyond the typical sensor set already present on modern automotive spark-ignition engines, including oxygen sensor(s) and engine controller. While the ICFC algorithm has been employed in production programs since 2009, to date these have all been naturally-aspirated engines using
Estimating internal residual during engine operation is essential to robust control during startup, steady state, and transient operation. Internal residual has a significant effect on combustion flame propagation, combustion stability and emissions. Accurate residual estimate also provides a better foundation for optimizing open loop fuel control during startup, while providing a basis for reducing emissions during closed loop control. In this paper we develop an improved model to estimate residual gas fraction by means of isolation and characterization of the physical processes in the gas exchange. Examining existing residuals model as the base, we address their deficiencies making changes to appropriate terms to the model. Existing models do not work well under wide angle dual independent cam phasing. The improved residual estimation model is not limited by the initial data set used for its calibration and does not need cylinder pressure data. The model can work with different valve
Results from a large set of HCCI experiments performed on a single-cylinder research engine fueled with different mixtures of iso-octane and n-heptane are presented and discussed in this paper. The experiments are designed to scrutinize fuel reactivity effects on the operating range of an HCCI engine. The fuel effects on upper and lower operating limits are measured respectively by the maximum pressure rise rate inside the cylinder and the stability of engine operation as determined by cycle-to-cycle variations in IMEP. Another set of experiments that examine the intake air heating effects on HCCI engine performance, exhaust emissions and operating envelopes is also presented. The effects of fuel reactivity and intake air heating on the HCCI ranges are demonstrated by constructing the operating envelopes for the different test fuels and intake temperatures. The paper discusses, in the light of the results, how the nonlinearity in fuel effects makes the dual fuel control approach less
Recent regulatory requirements have introduced, for the first time, catalyst exhaust systems with closed loop air/fuel control into the severe environment of stern-drive and inboard-powered pleasure marine vessels. These engines often maintain consistently high power levels due to vessel drag. Sea water used to cool the engine and exhaust is corrosive, and the engine experiences high g-loads when the planing vessel is used in wavy sea conditions. Engineers must face these challenges in order to develop a durable, efficient, clean-operating, and affordable marine engine. Computational fluid dynamics (CFD) has become a key tool to drive the design optimization of catalyst exhaust systems for marine applicatons. CFD models are used to simulate the unsteady exhaust gas flow of a fired engine. In particular, CFD is used to develop an exhaust system which will promote efficiency, low emissions, and robust closed-loop air fuel control. Increased gas residence time via catalyst flow uniformity
Low temperature combustion (LTC) in diesel engines offers attractive benefits through simultaneous reduction of nitrogen oxides and soot. However, it is known that the in-cylinder conditions typical of LTC operation tend to produce high emissions of unburned hydrocarbons (UHC) and carbon monoxide (CO), reducing combustion efficiency. The present study develops from the hypothesis that this characteristic poor combustion efficiency is due to in-cylinder mixture preparation strategies that are non-optimally matched to the requirements of the LTC combustion mode. In this work, the effects of three key fuel path parameters - injection fuel quantity ratio, dwell and injection timing - on CO and HC emissions were examined using a Central Composite Design (CCD) Design of Experiments (DOE) method. The experiments were performed on a single-cylinder diesel research engine operating in a high-EGR mixing-controlled LTC mode (EGR ~ 62%, intake O₂ = 8.5%) with a split fuel injection for all
This specification covers the requirements for format and outline of contents of operating instructions in published form or in manuscript form suitable for publication
This Aerospace Recommended Practice (ARP) covers a brief discussion of the icing problem in aircraft fuel systems and different means that have been used to test for icing. Fuel preparation procedures and icing tests for aircraft fuel systems and components are proposed herein as a recommended practice to be used in the aircraft industry for fixed wing aircraft and their operational environment only. In the context of this ARP, the engine (and APU) is not considered to be a component of the aircraft fuel system, for the engine fuel system is subjected to icing tests by the engine/APU manufacturer for commercial and specific military applications. This ARP is written mostly to address fuel system level testing. It also provides a means to address the requirements of 14 CFR 23.951(c) and 25.951(c). Some of the methods described in this document can be applied to engine and APU level testing or components of those application domains. This revision does not completely address new
This AIR discusses the history and development of endurance requirements, provides an analysis of test contaminant material and includes a discussion of future requirements
Actuators are critical engine and flight control components used in aerospace applications for motion and fuel controls. All aircraft today contain three primary types of actuators; electro-mechanical actuators (EMA), electro-hydraulic actuators (EHA), hydraulic actuators. Actuators control thrust vectoring of the main engines during powered ascent, movement of the aerodynamic control surfaces, and the positioning of propulsion system geometry and fuel/air control valves. EMAs consist of an electric motor and gear-train to reduce speed, translate motion, and provide appropriate load torque. Electro-hydraulic actuators are self contained systems that combine the benefits of an electric system with the benefits of hydraulic systems. EHAs use an electric motor to drive a hydraulic pump which develops hydraulic pressure to act on a cylinder to provide the mechanical actuation energy. Hydraulic actuators use a centralized hydraulic pump that supplies the required pressure. EHAs avoid the
In this paper we discuss in detail an algorithm that addresses cylinder-to-cylinder imbalance issues. Maintaining even equivalence-ratio (θ) control across all the cylinders of an engine is confounded by imbalances which include fuel-injector flow variations, fresh-air intake maldistribution and uneven distribution of Exhaust Gas Recirculation (EGR). Moreover, in markets that are growing increasingly cost conscious, with ever tightening emissions regulations, correcting for such mismatches must not only be done, but done with no additional cost. To address this challenge, we developed an Individual Cylinder Fuel Control (ICFC) algorithm that estimates each cylinder's individual θ and then compensates to correct for any imbalance using only existing production hardware. In our production-bound algorithm, modeling and control of the cylinders' dynamic θ was performed using a single switching oxygen sensor. Our ICFC algorithm was developed on a 2.4-l four-cylinder DOHC engine and it is in
This document discusses descriptions of fluid contamination products. These contaminants are used for design evaluation and formal component qualification/certification testing. Such tests are routinely performed on candidate aircraft engine fuel and pneumatic system components. Typical of these components are fuel pumps, fuel filters, fuel controls, pressurizing valves, flow dividers, selector valves, and combustor nozzles. The purpose of this document is to recommend standard descriptions to be used by specification writers
This paper identifies a select method for performing cylinder imbalance measurement, correction and diagnosis. The impetus is to address new U.S. Federal regulations that require the detection of excessive cylinder air-fuel ratio (AFR) imbalance, and doing so requires the foundational ability to measure and preferably remove cylinder imbalance via active closed-loop control. This function is called Individual Cylinder Fuel Control (ICFC). ICFC starts by extracting cylinder-imbalance information from the front oxygen sensor, and that information comes in the form a of continuous data stream. That stream is then parsed to create virtual sensors- one for each cylinder. Each virtual sensor acts as an imbalance or error signal which ICFC uses to correct and learn via feedback and feed-forward control for each cylinder. The cylinder imbalance diagnostic is enabled by the presence of ICFC. The diagnostic continuously monitors to determine if ICFC is operating within its control authority, or
The primary variable valve actuation strategies for diesel engines are variable late or early intake valve closing for control of effective compression ratio for Miller cycle and part-time HCCI, PCCI, or LTC; variable early exhaust valve opening for exhaust temperature control for after-treatment regeneration and improved engine transient response; on/off control of intake pre-bump and/or exhaust post-bump for IEGR and control of residual fraction; and on/off control of compression release and brake gas recirculation events for engine braking. Lost-motion hydraulic VVA is well suited to diesel engines due to the capability of on-off control of secondary events for IEGR and engine braking, high load capacity for early exhaust opening and engine braking, and inherent protection against valve-to-piston contact. Production requirements for VVA systems include proven reliability/durability, cost effectiveness, compact packaging, cold start capability, acceptable valve seating velocity over
This recommended practice describes a method for conducting room temperature, contaminated fuel, endurance testing when the applicable specification requires nonrecirculation of the contaminants. The objective of the test is to determine the resistance of engine fuel system components to wear or damage caused by contaminated fuel operation. It is not intended as a test for verification of the component’s filter life. ARP1827 is recommended for filter evaluation
This Aerospace Recommended Practice (ARP) covers a brief discussion of the icing problem in aircraft fuel systems and different means that have been used to test for icing. Fuel preparation procedures and icing tests for aircraft fuel systems and components are proposed herein as a recommended practice to be used in the aircraft industry for fixed wing aircraft and their operational environment only. In the context of this ARP, the engine is not considered to be a component of the aircraft fuel system, for the engine fuel system is subjected to icing tests by the engine manufacturer for commercial and particular military applications
With increasing pressures to reduce engine emissions in the small engines market there is a need to precisely meter the fuel flow into the engine under all running conditions. Therefore this cost competitive market requires a well engineered injection system that combines good control of fuel metering at all speed / load conditions, and meets the markets competitive pricing requirements. It must also offer the potential to allow these engines to meet stringent future legislation, leading to the addition of closed loop control with 3 way catalysts. This paper presents an experimental investigation into the effect of wall wetting and fuel injection strategy on a small engine. The engine was fitted with a novel form of port fuel injection, Pulse Count Injection (PCI) [1.] This novel high frequency digital fuelling system allows rapid oscillation of the fuel quantity from one engine cycle to the next. The result of the investigation is a novel fuelling strategy that enables good fuelling
This document discusses the history and development of endurance requirements, provides an analysis of test contaminant material and includes a discussion of future requirements
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