Search Results

A 500 hours endurance test was performed with a heavy-duty engine (Euro IV); MAN type D 0836 LFL 51 equipped with a PM-Kat®. As fuel 100% biodiesel was used that met the European specification EN 14214. The 500 hours endurance test included both the European stationary and transient cycle (ESC and ETC) as well as longer stationary phases. During the test, regulated emissions (carbon monoxide, nitrogen oxides, hydrocarbons and particulate matter), the particle number distribution and the aldehydes emission were continuously measured. For comparison, tests with fossil diesel fuel were performed before and after the endurance test. During the endurance test, the engine was failure-free for 500 hours with the biogenic fuel. There were almost no differences in specific fuel consumption during the test, but the average exhaust gas temperature increased by about 15°C over the time. Emissions changed only slightly during the test.

This paper attempts to assess the benefits of a unique distributed propulsion concept, known as the Multi-Gas Generator Fan (MGGF) system, over conventional turbofan engines on civilian vertical takeoff and landing (VTOL) applications. The MGGF-based system has shown the potential to address the fundamental technical challenge in designing a VTOL aircraft: the significant mismatch between the power requirements at lift-off/hover and cruise. Vehicle-level performance and sizing studies were implemented using the Grumman Design 698 tilt-nacelle V/STOL aircraft as a notional personal air vehicle (PAV), subjected to hypothetical single engine failure (SEF) emergency landing requirements and PAV mission requirements.

The present study aims at the implementation of a Matlab/Simulink environment to assess the performance (thrust, specific fuel consumption, aircraft/engine mass, cost, etc.) and environmental impact (greenhouse and pollutant emissions) of conventional and more electric aircrafts. In particular, the benefits of adopting more electric solutions for either aircrafts at given missions specifications can be evaluated. The software, named PLA.N.E.S, includes a design workflow for the input of aircraft specification, kind of architecture (e.g. series or parallel) and for the definition of each component including energy converter (piston engine, turboprop, turbojet, fuel cell, etc.), energy storage system (batteries, super-capacitors), auxiliaries and secondary power systems. It is also possible to setup different energy management strategies for the optimal control of the energy flows among engine, secondary equipment and storage systems during the mission.

The design process is an interactive feedback process where the performance of the design is compared with the performance specification. In aircraft design it is very important that the system is optimised with respect to different aspects such as performance and weight. Traditionally, and by necessity, the design procedure has began with some kind of performance specification followed by a conceptual design, and after that the system has been optimised (usually implicitly) with respect to the performance specification. Typically, aircraft design optimisation is characterised by a multitude of objectives that can be difficult to compare to each other, such as low fuel consumption, high speed and passenger comfort. Usually this is where the engineering judgement of the designer comes in. In traditional design it is often difficult to establish what was the result of design decisions and what was the result of pure optimisation.

In this study, the authors concluded that a super energy-efficient vehicle (SEEV) with fuel economy more than 100km/liter could be possible with the present technology level. The new environmentally-compatible vehicle was designed to mitigate urban warming, air pollution and CO2 emissions in the urban area. The authors evaluated optimal specifications of the new concept energy-efficient electric vehicle (EV) equipped with flywheel and photovoltaic (PV) cell and also reported the results of the running simulations for the proposed vehicle. The proposed SEEV will be very promising to mitigate urban and global warming, and toconserve fossil fuel consumption.

The Comet Rendezvous Asteroid Flyby (CRAF) mission involves seven years of flight from 0.6 to 4.57 Astronomical Units (AU), followed by about 915 days of maneuvering around a comet. Ground testing will characterize the very critical attitude control system thrusters' fuel consumption and performance for all anticipated fuel temperatures over thruster life. The ground test program characterization will support flight condition monitoring. A commercial software application hosted on a commercial microcomputer will control ground test operations and data acquisition using a newly designed thrust stand. The data acquisition and control system uses a graphics-based language and features a visual interface to integrate data acquisition and control.

In this paper, we address the thermal management issues which limit the lifespan, specific power and overall efficiency of an air-cooled rotary Wankel engine used in Unmanned Air Vehicles (UAVs). Our goal is to eliminate the hot spots and reduce the temperature gradients in the engine housing and side plates by aggressive heat spreading using heat pipes. We demonstrate by simulation that, for a specific power requirement, with heat spreading and more effective heat dissipation, thermal stress and distortion can be significantly reduced, even with air cooling. The maximum temperature drop was substantial, from 231°C to 129°C. The temperature difference (measure of temperature uniformity) decreased by 8.8 times (from 159°C to 18°C) for a typical UAV engine. Our heat spreaders would not change the frontal area of the engine and should have a negligible impact on the installed weight of the propulsion assembly.

The authors review the requirements, describe some of the unusual design features and characteristics, and present the performance and weight data for the new McCulloch TSIR-5190 aircraft engine. This powerplant is a highly turbosupercharged, two-stroke cycle, direct fuel injection, liquid cooled, 5 cyl radial engine of 190 cu in. displacement. Maximum rated horsepower is 270 at 3600 rpm, and the brake specific fuel consumption, over the range from half-to full power, is below 0.5 lb/bhp-hr. The estimated “ready to fly” weight for the production engine is 365 lb. Some comparisons are made with currently available engines.

Minimizing energy use on more electric aircraft (MEA) requires examining in detail the important decision of whether and when to use engine bleed air, ram air, electric, hydraulic, or other sources of power. Further, due to the large variance in mission segments, it is unlikely that a single energy source is the most efficient over an entire mission. Thus, hybrid combinations of sources must be considered. An important system in an advanced MEA is the adaptive power and thermal management system (APTMS), which is designed to provide main engine start, auxiliary and emergency power, and vehicle thermal management including environmental cooling. Additionally, peak and regenerative power management capabilities can be achieved with appropriate control. The APTMS is intended to be adaptive, adjusting its operation in order to serve its function in the most efficient and least costly way to the aircraft as a whole.

Trends towards lower vehicle fuel consumption and smaller environmental impact will increase the share of Diesel hybrids and Diesel Range Extended Vehicles (REV). Because of the Diesel engine presence and the ever tightening soot particle emissions, these vehicles will still require soot particle emissions control systems. Ceramic wall-flow monoliths are currently the key players in the Diesel Particulate Filter (DPF) market, offering certain advantages compared to other DPF technologies such as the metal based DPFs. The latter had, in the past, issues with respect to filtration efficiency, available filtration area and, sometimes, their manufacturing cost, the latter factor making them less attractive for most of the conventional Diesel engine powered vehicles. Nevertheless, metal substrate DPFs may find a better position in vehicles like Diesel hybrids and REVs in which high instant power consumption is readily offered enabling electrical filter regeneration.

In this paper modern optimization techniques are applied to an aircraft sizing problem. The paper starts by discussing how optimization could support the design activity and thereafter different methods of formulating the design problem as an optimization problem is discussed. Finally the problem of aircraft sizing is addressed by combining the presented optimization strategy with a simulation model of an aircraft based on mathematical models gathered from the literature. The outcome of the optimization is for example the optimal layout in order to minimize fuel consumption for a specific mission or the trade-off between the number of passengers and the fuel consumption per passenger.

An original instrument for fuel consumption measurement in reciprocating internal combustion engines for light aircraft has been developed and built. It is based on the detection of two parameters: the engine rotational speed and the manifold pressure. The aim of the instrument is to provide a fuel consumption indication which can be used during cruising. The instrument is not intended to replace the usual on board fuel level gauge, but can be used to integrate the flight information with the overall and instantaneous fuel consumption data, and with the cruising range indication, leading to a significant increase in flight safety. Some results of fuel consumption measurements from experimental tests are here presented and discussed. Such results were first obtained with the instrument installed on the engine during bench tests.

Diesel particle filters (DPF) have become a standard aftertreatment component for all current and future on-road diesel engines used in the US. In Europe the introduction of EUVI is expected to also result in the broad implementation of DPF's. The anticipated general trend in engine technology towards higher engine-out NOx/PM ratios results in a somewhat changing set of boundary conditions for the DPF predominantly enabling passive regeneration of the DPF. This enables the design of a novel filter concept optimized for low pressure drop, low thermal mass for optimized regeneration and fast heat-up of a downstream SCR system, therefore reducing CO₂ implications for the DPF operation. In this paper we will discuss results from a next-generation cordierite DPF designed to address these future needs.

A newly-invented "X"-configuration engine utilizing the Scotch yoke mechanism renders potential for the best power/weight ratio of any piston engine. Due to its inherent space and weight efficiency, low stress levels on critical components and low bearing pressures, this new configuration can be designed for aircraft applications using high-pressure 4-stroke diesel cycle with large numbers of cylinders - as many as 24 or 32 cylinders - to minimize engine weight and cross-sectional area. Given the efficiency advantage of 4-stroke turbo-diesel cycle over turbine engines, a study reveals that diesel X-engines may be a preferable solution to turbine engines for airplanes, helicopters and UAVs up to approximately 60000 lbs max. weight @takeoff. Calculations using existing turbine-powered aircraft as a baseline indicate potential for 35 to 50% lower fuel consumption with no compromise to maximum takeoff weight, payload, range, cruise speed, maximum speed or takeoff power.

A supersonic engine for a high Mach interceptor mission is modeled, and the requirements for the engine at different flight conditions are discussed. These include low fuel consumption at a non-afterburning supersonic dash Mach number for interception, and high thrust, both afterburning and non-afterburning, at a high subsonic Mach number for combat engagement. In addition, the engine should have low frontal area and low weight for a given sea level thrust rating. For the design point, the sea level static, standard day non-afterburning thrust is fixed at 20,000 lbs. The primary independent parameters varied in the study are fan pressure ratio, overall pressure ratio, turbine inlet temperature, throttle ratio, and extraction ratio. A design of experiments (DoE) is set up to vary the independent parameters to produce a meta-model for engine performance, geometry and weight.

Relevant Rotary Engine developments at Curtiss-Wright over the period 1958-1979 are reviewed. Applicable automotive engine developments, including Stratified Charge, flight test results and future projections are presented. The current 300 HP aircraft engine prototype development status is discussed relative to application of parallel direct injected unthrottled Stratified Charge technology gains which demonstrated automotive diesel engine fuel consumption levels, low emissions and multi-fuel operation in other Rotary engine models.

The crankcase-scavenged two-stroke-cycle engine is preferred in cases where low weight and high power output are paramount requirements. These qualities are most important in small pilotless aircraft. It was found that the main problem in the use of two-stroke cycle engines for this purpose, is a sharp decrease in the engine power with the increase in altitude. This is attributed not only to the low density of the ambient air, but also to the deterioration of the efficiency of the gas exchange process. In order to improve the engine performance at high altitude, it is proposed here to employ a stepped-piston engine. The engine is constructed of a stepped piston and a single stepped cylinder thus forming three compartments; a power, a compression and a crankcase compartment. In this arrangement, the fresh charge is compressed in the compression compartment before it enters the crankcase compartment.

This paper describes the concept of an air/fuel integrated thermal management system, which employs the VCS (Vapor Cycle System) for the refrigeration unit of the ECS (Environment Control System), while exchanging the heat between the VCS refrigerant and the fuel into the engine, and presents a feasibility study to apply the concept to the future all electric aircraft systems. The heat generated in an aircraft is transferred to the ECS heat exchanger by the recirculation of air and exhausted into the ram air. While some aircraft employ the fluid heat transfer loop, the transferred heat is exhausted into the ram air. The usage of ram air for the cooling will increase the ram drag and the fuel consumption, thus, less usage of ram air is preferable. Another source for heat rejection is the fuel. The heat exchange with the fuel does not worsen the fuel consumption, thus, the fuel is a preferable source.

This paper proposes a research project aimed into the development of a plastic or metallic thin film to be bonded over airplane external surfaces, that by having a nano-fabricated external layer with special properties could result in more elastic reflections of the air molecules impacting it, so creating an slip in the usually no slip air flow boundary layer condition, resulting in the reduction of the airplane friction drag, fuel consumption, CO2 emissions, and operational costs.