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Journal Article

Investigations on Spark and Corona Ignition of Oxymethylene Ether-1 and Dimethyl Carbonate Blends with Gasoline by High-Speed Evaluation of OH* Chemiluminescence

2018-03-01
Abstract Bio-fuels of the 2nd generation constitute a key approach to tackle both Greenhouse Gas (GHG) and air quality challenges associated with combustion emissions of the transport sector. Since these fuels are obtained of residual materials of the agricultural industry, well-to-tank CO2 emissions can be significantly lowered by a closed-cycle of formation and absorption of CO2. Furthermore, studies of bio-fuels have shown reduced formation of particulate matter on account of the fuels’ high oxygen content therefore addressing air quality issues. However, due to the high oxygen content and other physical parameters these fuels are expected to exhibit different ignition behaviour. Moreover, the question is whether there is a positive superimposition of the fuels ignition behaviour with the benefits of an alternative ignition system, such as a corona ignition.
Journal Article

Compatibility Assessment of Fuel System Thermoplastics with Bio-Blendstock Fuel Candidates Using Hansen Solubility Analysis

2018-03-01
Abstract The compatibility of key fuel system infrastructure plastics with 39 bio-blendstock fuel candidates was examined using Hansen solubility analysis. Fuel types included multiple alcohols, esters, ethers, ketones, alkenes and one alkane. These compounds were evaluated as neat molecules and as blends with the gasoline surrogate, dodecane and a mix of dodecane and 10% ethanol (E10D). The plastics included polyphenylene sulfide (PPS), polyethylene terephthalate (PET), polytetrafluoroethylene (PTFE), polyvinylidene fluoride (PVDF), polyoxymethylene (POM), polybutylene terephthalate (PBT), polypropylene (PP), high density polyethylene (HDPE), along with several nylon grades. These materials have been rigorously studied with other fuel types, and their volume change results were found to correspond well with their predicted solubility levels.
Journal Article

Improvement in Gear Shift Comfort by Reduction in Double Bump Force of Passenger Vehicles

2017-10-08
Abstract In today’s competitive automobile market, driver comfort is at utmost importance and the bar is being raised continuously. Gear Shifting is a crucial customer touch point. Any issue or inconvenience caused while shifting gear can result into customer dissatisfaction and will impact the brand image. While there are continual efforts being taken by most of the car manufactures, “Double Bump” in gearshift has remained as a pain area and impact severely on the shift feel. This is more prominent in North-South (N-S) transmissions. In this paper ‘Double Bump’ is a focus area and a mathematical / analytical approach is demonstrated by analyzing ‘impacting parameters’ and establishing their co-relation with double bump. Additionally, the results are also verified with a simulation model.
Journal Article

Driveline Ratio Selection and Shift Map Optimization for Automatic Transmission Vehicle at Concept Phase through Simulations

2017-10-08
Abstract Traditionally driveline ratios are selected based on trial and error method of proto vehicle testing. This consumes lot of time and increases overall vehicle development effort. Over last few decades, simulation-based design approach has been extensively used to alleviate this problem. This paper describes torque converter and final drive ratio (FDR) selection at concept phase for new Automatic Transmission (AT) vehicle development. Most of the critical data required for simulating vehicle performance and fuel economy (FE) targets were not available (e.g. shift map, clutch slip map, pedal map, dynamic torque, coast down, etc.) at an initial stage of the project. Hence, the risk for assuming right inputs and properly selecting FDR/Torque converter was particularly high. Therefore, a validated AVL Cruise simulation model based on an existing AT vehicle was used as a base for new AT vehicle development to mitigate the risk due to non-availability of inputs.
Journal Article

Statistical Modeling of Plate Clearance Distribution for Wet Clutch Drag Analysis

2017-10-08
Abstract Wet clutch packs are the key component for gear shifting in the step-ratio automatic transmission system. The clutch plates are coupled or de-coupled to alter gear ratios based on the driver’s actions and vehicle operating conditions. The frictional interfaces between clutch plates are lubricated with automatic transmission fluid (ATF) for both thermal and friction management. In a 10-speed transmission, there may be as many as 6 clutch packs. Under typical driving conditions, 2 to 3 clutch packs are open, shearing ATF and contributing to energy loss. There is an opportunity to improve fuel economy by reducing the associated viscous drag. An important factor that directly affects clutch drag is the clearance between rotating plates. The axial position of clutch plates changes continuously during operation. It is known in practice that not only the total clearance, but also its distribution between the plates affects the viscous drag.
Journal Article

Design, Analysis, and Optimization of a Multi-Speed Powertrain for Class-7 Electric Trucks

2018-04-17
Abstract The development, analysis, and optimization of battery electric class-7 heavy-duty trucks equipped with multi-speed transmissions are discussed in this paper. The designs of five new traction motors-fractional-slot, concentrated winding machines-are proposed for use in heavy-duty electric trucks. The procedure for gear-ratio range selection is outlined and ranges of gear ratios for three-to six-speed transmission powertrains are calculated for each of the proposed electric traction motors. The simulation and gear-ratio optimization tasks for class-7 battery electric trucks are formulated. The energy consumption of the e-truck with the twenty possible powertrain combinations is minimized over the four driving cycles and the most efficient powertrain layouts that meet the performance criteria are recommended.
Journal Article

Comparative Study of Different Air Supply Systems for Automotive Fuel Cell Applications

2019-05-10
Abstract The dynamic and efficiency of automotive fuel cell drives is significantly influenced by air supply system. Different air compression architectures use electric compressor (EC), electric turbocharger (ETC), or a serial booster (SB) consisting of turbocharger and electric compressor. These three variants of air compression systems were modeled using a map approach and added to a 0D fuel cell air supply model. The characteristic maps of the turbomachinery were measured on the test bench under fuel cell conditions. Subsequently, the calculated isentropic efficiencies were corrected with respect to heat transfer phenomena occurring during the measurement. Moreover, a scaling method for the maps of the turbomachinery is explained. The initial simulation of the air compression systems with equal diameters for the turbomachinery showed no difference in the mechanical power demand.
Journal Article

Selection of Reference Flux Linkage for Direct Torque Control Based Induction Motor Drive in Electric Vehicle Applications

2019-04-08
Abstract The surge in economic activities, in the developing nations, has resulted in rapid expansion of urban centres. This expansion of cities has caused a rapid increase in vehicular traffic, which in turn has caused deterioration of air quality. To overcome the problem of unprecedented air pollution, the governments worldwide have framed policies for faster adoption of electric vehicles. One of the major challenges faced is the development of low- cost drive for these vehicles and keeping the imports to a minimum. As a result of this, the trend is to move away from the permanent magnet-based motor technology and to use induction motor-based drivetrain. For the induction motors to be successful in electric vehicle drivetrain application, it is important to have a robust speed control algorithm. This work aims at adapting a direct torque control technique for induction motor’s speed control.
Journal Article

Electric Vehicle with Multi-Speed Transmission: A Review on Performances and Complexities

2018-12-04
Abstract Electric vehicles (EVs) with multi-speed transmission offer improved performances compared to those with single speed transmission system in terms of top speed, fast acceleration, or gradeability along with driving range. In this study, relevant literature is extensively analyzed to explore the performances and associated complexities with multi-speed automatic manual/mechanical transmission (AMT) system in EVs. In EV powertrain, the only torque generator component is electric motor, which is not equally efficient throughout wider speed range. To the other end, vehicles need to run at different speeds in diverse driving conditions. The study shows that multi-speed transmission system enables efficient operation of electric motor by choosing an appropriate gear at different driving torque-speed demands and thus contributes to achieve desired vehicle performances at minimum energy consumption.
Journal Article

Compression Ratio Control of Free Piston Linear Generator with In-Cylinder Pressure Feedforward

2018-06-28
Abstract The free piston linear generator (FPLG) is a novel machine that functions as an Auxiliary Power Unit (APU) for hybrid electric vehicles, which contains two opposed free piston engines and one linear generator between them. FPLG has attracted extensive interest for its potential advantages in terms of high power density and multi-fuel flexibility. The guarantee of FPLG generating electricity steadily and efficiently is the high controllability of compression ratio. In this article, a control-oriented discrete-time model was established based on Otto cycle. Since the fluctuation of in-cylinder pressure caused by instable fuel injection mass and combustion process is the main disturbance, a composite controller is designed to precisely control the compression ratio of FPLG. The composite controller is made up of a feedforward controller and a feedback tracking controller.
Journal Article

Multi-Attribute, System-Level Design Process for Automotive Powertrain Electric Drives: An Integrated Approach

2018-06-05
Abstract This article presents an electric drive powertrain design and virtual integration methodology in the context of electric vehicle systems. In the first stage, using the Model-Based System Engineering paradigm, the electric vehicle performance requirements are translated into electric drive target specifications using a system-level vehicle model. Subsequently, a functional electric drive subsystem-level model is developed based on magnetic co-energy and iron losses data obtained from a reference electric machine design. The functional electric drive model is scaled in order to meet the requested specifications, and it is coupled with different 1D (i.e. lumped-parameter) multi-physics sub-models that are later integrated into the electric vehicle system-level model. At the electric drive level the torque ripple and Noise, Vibration and Harshness characteristics are analyzed.
Journal Article

Carbon Monoxide Density Pattern Mapping from Recreational Boat Testing

2018-10-04
Abstract Exposure to carbon monoxide (CO) gas can cause health risks for users of recreational boats and watercraft. Activities such as waterskiing, wakeboarding, tubing, and wakesurfing primarily utilize gasoline engine-driven vessels which produce CO as a combustion by-product. Recent watersports trends show an increase in popularity of activities which take place closer to the stern of the boat (such as wakesurfing) as compared to traditional waterskiing and wakeboarding. Advancements in gas emissions treatment in marine engine exhaust system designs have reduced risks for CO exposure in some boats. This article presents results from on-water testing of three recreational boats, reports average and maximum values of CO levels under various conditions, and exhibits mapping of the density of CO relative to the stern of the test vessels.
Journal Article

Contribution of the Mechanical Linkage in Gear Shift Feel of North-South Transmission

2017-10-08
Abstract Today’s automotive industry is facing cutthroat competition, especially in passenger vehicle business. Manufacturers around the globe are developing innovative and new products keeping focus on end customer; thus customer's opinion and perception about the product has become a factor of prime importance. Customer touch points such as gear shift lever, clutch, brakes, steering etc. are thus gaining more and more importance. Car companies are trying to induce more and more luxuries in these touch points so that they impress customer and create a positive opinion about the product. On the other hand manufacturers are also trying to manage profits. Companies thus need to find the best fit solution for improvising customer touch points with optimized costs. The performance of these touch points is driven by subsystems of mechanical components like mechanical linkage.
Journal Article

Enhanced Low-Order Model with Radiation for Total Temperature Probe Analysis and Design

2018-05-16
Abstract Analysis and design of total temperature probes for accurate measurements in hot, high-speed flows remains a topic of great interest in aerospace propulsion and a number of other engineering areas. One can apply detailed computational methods for simultaneous convection, conduction and radiation heat transfer, but such approaches are not suitable for rapid, routine analysis and design studies. For these studies, there is still a place for low-order approximate methods, and that is the subject of this paper. Here, an enhanced, low-order model is presented that includes conduction with variable thermal conductivity, convection with varying convection coefficient, varying diameter (and thus area) along the length of the sensor and radiation, all implemented in a convenient MATLAB code.
Journal Article

Exploring the Potential of Combustion on Titan

2018-04-07
Abstract Significant attention has been focused on Mars due to its relative proximity and possibility of sustaining human life. However, its lack of in-situ sources of energy presents a challenge to generate needed energy on the surface. Comparatively, Titan has a nearly endless source of fuel in its atmosphere and lakes, but both are lacking in regards to their oxidizing capacity. The finding of a possible underground liquid ammonia-water lake on Titan suggests that oxygen might actually be within reach. This effort provides the first theoretical study involving a primary energy generation system on Titan using the atmosphere as a fuel and underground water as the source for the oxygen via electrolysis from wind generated electricity.
Journal Article

Improve Heat Resistance of Composite Engine Cowlings Using Ceramic Coating Materials, Experimental Design and Testing

2018-06-04
Abstract A large amount of heat generated in the engineering compartment in a hovering helicopter may lead to premature degradation of inner skin of its engine cowling and cause serious failure on the engine cowling. This study proposes a solution of improving heat resistance of the helicopter engine cowlings by replacing the currently used intumescent coating with a ceramic coating material, Cerakote C-7700Q. Oven and flame tests were designed and conducted to evaluate the heat resistance of Cerakote C-7700Q. The test results show that the currently used painting scheme of the engine cowlings failed the 220°C oven test while after replacing the epoxy seal coat with the Cerakote, the new painting system passed the 220°C test in regards to painting bubbling. Based on that, a new painting scheme with C-7700Q implemented was recommended.
Journal Article

Modeling of Ducted-Fan and Motor in an Electric Aircraft and a Preliminary Integrated Design

2018-10-04
Abstract Electric ducted-fans with high power density are widely used in hybrid aircraft, electric aircraft, and VTOL vehicles. For the state-of-the-art electric ducted-fan, motor cooling restricts the power density increase. A motor design model based on the fan hub-to-tip ratio proposed in this article reveals that the thermal coupling effect between fan aerodynamic design and motor cooling design has great potential to increase the power density of the motor in an electric propulsion system. A smaller hub-to-tip ratio is preferred as long as the power balance and cooling balance are satisfied. Parametric study on a current 6 kW electric ducted-fan system shows that the highest motor power density could be increased by 246% based on the current technology. Finally, a preliminary design was obtained and experiments were conducted to prove the feasibility of the model.
Journal Article

High Power-Density, High Efficiency, Mechanically Assisted, Turbocharged Direct-Injection Jet-Ignition Engines for Unmanned Aerial Vehicles

2019-05-02
Abstract More than a decade ago, we proposed combined use of direct injection (DI) and jet ignition (JI) to produce high efficiency, high power-density, positive-ignition (PI), lean burn stratified, internal combustion engines (ICEs). Adopting this concept, the latest FIA F1 engines, which are electrically assisted, turbocharged, directly injected, jet ignited, gasoline engines and work lean stratified in a highly boosted environment, have delivered peak power fuel conversion efficiencies well above 46%, with specific power densities more than 340 kW/liter. The concept, further evolved, is here presented for unmanned aerial vehicle (UAV) applications. Results of simulations for a new DI JI ICE with rotary valve, being super-turbocharged and having gasoline or methanol as working fuel, show the opportunity to achieve even larger power densities, up to 430 kW/liter, while delivering a near-constant torque and, consequently, a nearly linear power curve over a wide range of speeds.
Journal Article

Design and Experiment on Aircraft Electromechanical Actuator Fan at Different Altitudes and Rotational Speeds

2019-06-07
Abstract For electromechanical actuators (EMAs) and electronic devices cooling on aircraft, there is a need to study cooling fan performance at various altitudes from sea level to 12,000 m where the ambient pressure varies from 1 to 0.2 atm. As fan static pressure head is proportional to air density, the fan’s rotational speed has to be increased significantly to compensate for the low ambient pressure of 0.2 atm at the altitude of 12,000 m. To evaluate fan performance for EMA cooling, a high-rotational-speed, commercially available fan made by Ametek with a diameter of ~82 mm and ~3 m3/min zero-load open cooling flow rate when operating at 20,000 rpm was chosen as the baseline. According to fan scaling laws, this fan was expected to meet the cooling needs for an EMA when operating at 0.2 atm. Using a closed flow loop, the performance of the fan operating in the above ambient pressure range and at a rotational speed between 15,000 and 30,000 rpm was evaluated.
Journal Article

Process Regulations and Mechanism of WEDM of Combustor Material

2019-06-07
Abstract This study discusses the experimental investigation on WEDM of combustor material (i.e., nimonic 263). Experimentation has been executed by varying pulse-on time (Ton), pulse-off time (Toff), peak current (Ip), and spark gap voltage (Sv). Material removal rate (MRR), surface roughness (SR), and wire wear rate (WWR) are employed as process performance characteristics. Experiments are designed as per the box-Behnken design technique. Parametric optimization has also been performed using response surface methodology. Besides this, field-emission scanning electron microscope (FE-SEM) and an optical microscope are utilized to characterize WEDMed and worn-out wire surfaces. It is observed that both surfaces contain micro-cracks, craters, spherical droplets, and a lump of debris. Furthermore, the mechanism of recast layer formation has been critically evaluated to apprehend a better understanding of the technique. The key features of the experimental procedure are also highlighted.
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