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Technical Paper

Aerodynamic Analysis on under Body Drag and Vehicle Performance of Active Front Spoiler for High CG Vehicles

Vehicle aerodynamic drag reduction is the effective technique to enhance the fuel economy, performance and top speed of a vehicle. Out of the total drag, the underbody drag contributes about 40-50% by the parts like wheel arch, wheel housing, and the wheels. This further increases in the case of vehicles with higher CG. Thus, it seems logical to focus attention on the underbody aerodynamic drag reduction. In this study, an active spoiler is placed towards the front end of the vehicle which will divert the air flow from the front towards the radiator. The active spoiler revolves according to the signals received from the radar sensors placed at the lower end to detect obstacles which will prevent it from damage. The aim of the study is to examine the effect of the air flow diversion on underbody drag. The effect of air flow diversion on fuel consumption, radiator effectiveness and top speed is numerically evaluated.
Technical Paper

Aerodynamic Drag Reduction of an Intercity Bus through Surface Modifications - A Numerical Simulation

The maximum power produced by the Engine is utilized in overcoming the Aerodynamic resistance while the remaining has been used to overcome rolling and climbing resistance. Increasing emission and performance demands paves way for advanced technologies to improve fuel efficiency. One such way of increasing the fuel efficiency is to reduce the aerodynamic drag of the vehicle. Buses emerged as the common choice of transport for people in India. By improving the aerodynamic drag of the Buses, the diesel consumption of a vehicle can be reduced by nearly about 10% without any upgradation of the existing engine. Though 60 to 70 % of pressure loads act on the frontal surface area of the buses, the most common techniques of reducing the drag in buses includes streamlining of the surfaces, minimizing underbody losses, reduced frontal area, pressure difference between the front & rear area and minimizing of flow separation & wake regions.
Technical Paper

Highly Efficient Civil Aviation, Now via Operations - AAR and Challenges

Global civil aviation growth at 5+% yearly poses extreme environmental challenges. Advances have appeared gradually through improved aerodynamic shapes, using carbon fibres, and enhanced engines; however, as these technologies mature, direct efficiency advances require increasing effort. Often Passenger convenience is forgotten e.g. the long-range air traffic has developed on hub-spoke basis implying extra feeder flights, transit passenger inconveniences, capacity issues. Efficiency metrics emphasize “Why, How & What”, with an understanding of the range sensitivities, operational concepts and performance goals via the important “X-factor”. For given range, current aircraft are “greener” than previous generations. Medium range aircraft s are always greener than those for short or long ranges. However, currently, the major trend is for the latter: twin-aisle A350, A380, B787, B777X (10+% payload, 40+% fuel to MTOW).
Technical Paper

Comparison of Duty-Cycle of a Lithium-Ion Battery for Electric Airplane and Electric Vehicle Applications

In this study, the duty-cycle of a commercial lithium-ion battery (LIB) for a typical passenger airplane (Bombardier CRJ200) is obtained and compared to the duty- cycle of the same LIB for electric vehicles. For this purpose, the velocity and altitude of the airplane is monitored during a typical flight and the instantaneous mechanical power of the airplane is obtained by modeling. Based on the airplane required power and the characteristics of the LIB, a battery pack is designed for the airplane. Then, the duty-cycle of a LIB cell in the battery pack is yielded. The duty-cycle of the same LIB for a typical electric vehicle is also obtained from modeling based on the Highway Fuel Economy Test (HWFET), New York City Cycle (NYCC) and United States 2006 (US06) drive-cycles. Finally, the duty-cycle of the LIB for two different applications of electric airplane and electric vehicle is compared. The duty-cycles obtained in this study can be employed to study the lifespan of LIBs.
Technical Paper

Mission-based Design Space Exploration for Powertrain Electrification of Series Plugin Hybrid Electric Delivery Truck

Hybrid electric vehicles (HEV) are essential for reducing fuel consumption and emissions. However, when analyzing different segments of the transportation industry, for example, public transportation or different sizes of delivery trucks and how the HEV are used, it is clear that one powertrain may not be optimal in all situations. Choosing a hybrid powertrain architecture and proper component sizes for different applications is an important task to find the optimal trade-off between fuel economy, drivability, and vehicle cost. However, exploring and evaluating all possible architectures and component sizes is a time-consuming task. A search algorithm, using Gaussian Processes, is proposed that simultaneously explores multiple architecture options, to identify the Pareto-optimal solutions.
Technical Paper

Comparison of 1-D Modelling Approaches for Wankel Engine Performance Simulation and Initial Study of the Direct Injection Limitations

Recent interest in the possible use of Wankel engines as range extenders for electric vehicles has prompted renewed investigations into the concept. While not presently used in the automotive industry, the type is well established in the unmanned aerial vehicles industry, and several innovative approaches to sealing and cooling have recently been developed which may result in improved performance for ground vehicle applications. One such UAV engine is the 225CS, a 225 cc/chamber single-rotor engine manufactured by Advanced Innovative Engineering (UK) Ltd. To be able to analyse the parameters, opportunities and limitations of this type of engine a model was created in the new dedicated Wankel modelling environment of AVL BOOST. For comparison a second model was created using the established method of modelling Wankel engines by specifying an ‘equivalent’ 3-cylinder 4-stroke reciprocating engine.
Technical Paper

A Potential Solution for High-Efficiency Aircraft Powerplants - the Scotch Yoke X-Engine Aero-Diesel

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.
Technical Paper

Endurance Testing for Wankel Rotary Engine

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.
Journal Article

Lightweight Composite Air Cargo Containers

Air cargo containers are used to load freight on various types of aircrafts to expedite their handling. Fuel cost is the largest contributor to the total cost of ownership of an air cargo container. Therefore, a better fuel economy could be achieved by reducing the weight of such containers. This paper aims at developing innovative, lightweight design concepts for air cargo containers that would allow for weight reduction in the air cargo transportation industry. For this purpose, innovative design and assembly concepts of lightweight design configurations of air cargo containers have been developed through the applications of lightweight composites. A scaled model prototype of a typical air cargo container was built to assess the technical feasibility and economic viability of creating such a container from fiber-reinforced polymer (FRP) composite materials. The paper is the authoritative source for the abstract.
Technical Paper

Evaluation of Paralleled Generation Architectures for Civil Aircraft Applications

The aviation industry has witnessed a technological shift towards the More Electric Aircraft (MEA) concept. This shift has been driven by a number of perceived benefits including performance optimization and reduced life-cycle costs. Increased electrification within MEA has made aircraft electrical networks larger and more complex and this necessitates an increased electrical power offtake from the engine. The paralleling of multiple generation sources across the aircraft is one potential design approach which could help improve engine operability and fuel efficiency within more-electric aircraft platforms. Accordingly, this paper will investigate options for the realization of paralleled generation systems within the context of current design and certification rules. The paper first illustrates, through simulation, that MIL-STD-704F voltage envelopes may be breached for some interconnected electrical architectures under fault conditions.
Journal Article

Aerodynamic Drag of Passenger Cars at Yaw

The aerodynamic drag characteristics of a passenger car are typically defined by a single parameter, the drag coefficient at zero yaw angle. While this has been acceptable in the past, it may not allow a true comparison between vehicles with regard to the impact of drag on performance, especially fuel economy. An alternative measure of aerodynamic drag should take into account the effect of non-zero yaw angles and some proposals have been made in the past, including variations of wind-averaged drag coefficient. For almost all cars the drag increases with yaw, but the increase can vary significantly between vehicles. In this paper the effect of various parameters on the drag rise with yaw are considered for a range of different vehicle types. The increase of drag with yaw is shown to be an essentially induced drag, which is strongly dependent on both side force and lift. Shape factors which influence the sensitivity of drag with yaw are discussed.
Technical Paper

Development of the Aerodynamics of the New Nissan Murano

The new Murano was developed with special emphasis on improving aerodynamics in order to achieve fuel economy superior to that of competitor models. This paper describes the measures developed to attain a drag coefficient (CD) that is overwhelmingly lower than that of other similar models. Special attention was paid to optimizing the rear end shape so as to minimize rear end drag, which contributes markedly to the CD of sport utility vehicles (SUVs). A lower grille shutter was adopted from the early stage of the development process. When open, the shutter allows sufficient inward airflow to ensure satisfactory engine cooling; when closed, the blocked airflow is actively directed upward over the body. The final rear end shape was tuned so as to obtain the maximum aerodynamic benefit from this airflow. In addition, a large front spoiler was adopted to suppress airflow toward the underbody as much as possible.
Technical Paper

Aerodynamic Drag Reduction - from Conceptual Design on a Simplified Generic Model to Full-Scale Road Tests

Road transportation by trucks is the major part of the goods transportations system in the European Union (EU), and there is a need for increased fuel efficiency. While truck manufacturers already spend significant resources in order to reduce the emissions from their vehicles, most truck manufacturers do not control the shape of the trailer and/or swap bodies. These devices are usually manufactured by different companies that cannot consider the overall aerodynamics around the complete vehicle. By use of Computational Fluid Dynamics (CFD) and previous wind tunnel experiments, the flow around a simplified generic tractor-trailer model has been investigated. With better understanding of the flow features around the tractor with attached trailer or swap bodies, an improved design of the trailer and swap body can be achieved, which is the aim for the project.
Journal Article

Hybrid-Electric, Heavy-Fuel Propulsion System for Small Unmanned Aircraft

A series hybrid-electric propulsion system has been designed for small rapid-response unmanned aircraft systems (UAS) with the goals of improving endurance, providing flexible and responsive electric propulsion, and enabling heavy fuel usage. The series hybrid architecture used a motor-driven propeller powered by a battery bank, which was recharged by an engine-driven generator, similar to other range-extended electric vehicles. The engine design focused on a custom, two-stroke, lean-burn, compression-ignition (CI), heavy-fuel engine, which was coupled with an integrated starter alternator (ISA) to provide electrical power. The heavy-fuel CI engine was designed for high power density, improved fuel efficiency, and compatibility with heavy fuels (e.g., diesel, JP-5, JP-8). Commercially available gasoline spark-ignition engines and heavy-fuel spark-ignition engines were also considered in the trade study.
Journal Article

The Aerodynamics of a Small Car Overtaking a Truck

The influence of a large truck on the aerodynamics of a small passenger car in an overtaking manoeuvre on the motorway was considered, many years ago, during the 1970's, to be a potential problem for the vehicle aerodynamicist. The concern never became significant as vehicle architecture evolved and car weights increased. The current drive for improved fuel economy is advocating that a considerable reduction in vehicle mass is desirable and therefore it may be time to readdress the significance of the truck passing manoeuvre. A quasi-steady experiment has been undertaken at small model scale to examine the aerodynamic characteristics of a small car in proximity to a large truck. Measurements at yaw were included to crudely simulate the effects of a crosswind. The wind tunnel data is presented and the limitations of the experimental procedure are discussed.
Technical Paper

Compressor Airfoil Protective Coating for Turbine Engine Fuel Efficiency

Small media ingestion has been known to cause erosion and result in corrosion to compressor components of gas turbine engines. Compressor degradation negatively impacts fuel consumption, engine performance, reliability, and maintenance costs. Power losses in the compressor section are often unrecoverable without increasing fuel consumption; therefore, protecting the compressor from excessive erosion/corrosion may extend the life of an engine, and reduce fuel, maintenance costs, and emissions. A study was conducted to investigate the effect of a new compressor blade and vane erosion/corrosion resistant coating on two Rolls-Royce T56-A7-B engines. The study included a comprehensive sand ingestion test that compared the performance and hardware condition of uncoated and coated compressor airfoils before, during, and after sand ingestion of 135 pounds of sand mixture.
Journal Article

Potential of Several Alternative Propulsion Systems for Light Rotorcrafts Applications

Reducing greenhouse gas emissions to limit global warming is becoming one of the key issues of the 21st century. As a growing contributor to this phenomenon, the aeronautic transport sector has recently taken drastic measures to limit its impact on CO2 and pollutants, like the aviation industry entry in the European carbon market or the ACARE objectives. However the defined targets require major improvements in existing propulsion systems, especially on the gas generator itself. Regarding small power engines for business aviation, rotorcrafts or APU, the turboshaft is today a dominant technology, despite quite high specific fuel consumption. In this context, solutions based on Diesel Internal Combustion Engines (ICE), well known for their low specific fuel consumption, could be a relevant alternative way to meet the requirements of future legislations for low and medium power applications (under 1000kW).
Technical Paper

Defining Requirements for the Implementation of Interconnected Generation in Future Civil Aircraft

In addition to providing thrust, the engines on conventional civil jet airliners generate power for on-board systems and ancillary loads in the form of pneumatic, hydraulic and electrical power. Reduced fuel-burn and efficiency targets have driven the move towards More Electric Aircraft (MEA) technology which seeks to replace hydraulic and pneumatic loads with electrical equivalents. This technological shift, in conjunction with a growing electrical power load per passenger in general, has greatly increased the electrical power demands of aircraft in recent years - over 1 MVA for the Boeing 787 for example. With increasing fuel prices, there is a growing need to optimise efficiency of power extraction from the aircraft engines for the electrical system and loads. In particular, the utilisation of multi-shaft power off-takes, interconnected generation and power sharing between shafts is thought to offer potentially significant engine operability and fuel efficiency benefits.
Technical Paper

912iS Fuel Injected Aircraft Engine

The 912 engine is a well known 4-cylinder horizontally opposed 4-stroke liquid-/air-cooled aircraft engine. The 912 family has a strong track record: 40 000 engines sold / 25 000 still in operation / 5 million flight hours annually. 88% of all light aircraft OEMs use Rotax engines. The 912iS is an evolution of the Rotax 912ULS carbureted engine. The “i” stands for electronic fuel injection which has been developed according to flight standards, providing a better fuel efficiency over the current 912ULS of more than 20% and in a range of 38% to 70% compared to other competitive engines in the light sport, ultra-light aircraft and the general aviation industry. BRP engineers have incorporated several technology enhancements. The fully redundant digital Engine Control Unit (ECU) offers a computer based electronic diagnostic system which makes it easier to diagnose and service the engine.
Journal Article

Technology Selection for Optimal Power Distribution Efficiency in a Turboelectric Propulsion System

Turboelectric propulsion is a technology that can potentially reduce aircraft noise, increase fuel efficiency, and decrease harmful emissions. In a turbo-electric system, the propulsor (fans) is no longer connected to the turbine through a mechanical connection. Instead, a superconducting generator connected to a gas turbine produces electrical power which is delivered to distributed fans. This configuration can potentially decrease fuel burn by 10% [1]. One of the primary challenges in implementing turboelectric electric propulsion is designing the power distribution system to transmit power from the generator to the fans. The power distribution system is required to transmit 40 MW of power from the generator to the electrical loads on the aircraft. A conventional aircraft distribution cannot efficiently or reliably transmit this large amount of power; therefore, new power distribution technologies must be considered.