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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

Exploring Engine Oil Reactivity Effects on End Gas Knock in a Direct-Injection Spark Ignition Engine

2018-03-07
Abstract An experimental study was conducted in a direct-injection (DI) spark-ignited engine to determine the extent to which oil reactivity impacts combustion phasing and knock propensity. Three engine oils were examined: a baseline 20W30 oil from conventional base stock, a 5W30 oil from a synthetic base stock, and a jet oil from a hindered ester base stock. The engine was operated at a constant fueling rate of 24.7 mg/injection for two engine speed conditions (1500 and 2000 rpm) using two cam profile conditions (high and low lift), for a total of four operating conditions. Spark timing sweeps were conducted at each of the four operating conditions. Results were analyzed for an engine oil impact on combustion phasing, cycle-to-cycle variability, combustion duration, knock propensity, and knock intensity. No correlation between engine oil type and any of these performance metrics could be identified.
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

Soot Observations and Exhaust Soot Comparisons from Ethanol-Blended and Methanol-Blended Gasoline Combustion in a Direct-Injected Engine

2018-05-07
Abstract Particulate formation was studied under homogeneous-intent stoichiometric operating conditions when ethanol-blended (E10) or methanol-blended (M20) gasoline fuel was injected during intake stroke of a 4-stroke direct-injected engine. The engine was tested at wide open throttle under naturally aspirated conditions for a speed-load of 1500 rev/min and 9.8 bar indicated mean effective pressure. In-cylinder soot observations and exhaust soot measurements were completed for different fuel rail pressures, injection timings, coolant and piston temperatures of the optical engine. Fuel delivery settings were tested with both single and split injections during intake stroke. The target piston temperature of the optical engine was attained using pre-determined number of methane port fuel injection firing cycles. Overall, the in-cylinder soot observations correlated well with the engine-out soot measurements. A warmer cylinder head favored soot reduction for both fuels.
Journal Article

Corrosion Behavior of Automotive Materials with Biodiesel: A Different Approach

2018-05-07
Abstract The issue of material compatibility of biodiesel has been discussed by few researchers but the reported corrosion rates were alarmingly high. This study addresses the corrosion issue of biodiesel with automotive materials with a different but systematic approach following SAE J1747 standard. In earlier studies while conducting material compatibility studies with biodiesel, mention of any specific standard/s has not been generally observed. Earlier studies were conducted by storing the samples for a long time without any change of fuel. However in actual automotive application, change of fuel is always on a periodic basis due to consumption of fuel and the SAE standard recommends for the same. This difference has a significant effect on the material compatibility as this periodic change does not result in making the fuel particularly biodiesel more acidic which is otherwise when stored for a long time during the test period.
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

Impact of Siloxanes in Biomethane on the Performance of a CNG Vehicle

2018-03-23
Abstract In this paper, the results of experiments to determine the effects of silicon-containing compounds in biogas on the performance of spark-ignited gas engines for use in CNG vehicles are presented. Initial research was performed on micro-CHP units, which have many features common with automotive engines, to identify engine components sensitive for silica deposition prior to investigating a practical CNG engine. The experiments on the micro-CHP units revealed that the catalyst was the most sensitive part for silica fouling, with strong impact on the reduction of NOx. With the insight gained from these experiments, an 9-week endurance test was performed on a light-duty CNG vehicle.
Journal Article

Literature Review on the Effects of Organometallic Fuel Additives in Gasoline and Diesel Fuels

2018-04-18
Abstract A literature review was conducted and fuel survey data were obtained to identify the use of metallic fuel additives (MFAs) within market fuels and determine their effects on engines, exhaust systems, and vehicle performance. The primary focus was on modern vehicles equipped with on-board diagnostic (OBD) systems and advanced emissions control systems. For gasoline, this includes vehicles categorized as National Low Emission Vehicles (NLEV) and Tier 2 or beyond in the U.S., and Euro-3 through Euro-6 in the EU. For diesel, this includes engines/vehicles with original equipment manufacturer (OEM)-equipped oxidation catalysts and diesel particulate filters. The literature search of peer-reviewed papers and other publicly available articles returned over 100 items relevant to the use of organometallic fuel additives, but did not provide significant evidence of widespread use of MFAs in either gasoline or diesel fuels.
Journal Article

Uncertainty Assessment of Octane Index Framework for Stoichiometric Knock Limits of Co-Optima Gasoline Fuel Blends

2018-10-25
Abstract This study evaluates the applicability of the Octane Index (OI) framework under conventional spark ignition (SI) and “beyond Research Octane Number (RON)” conditions using nine fuels operated under stoichiometric, knock-limited conditions in a direct injection spark ignition (DISI) engine, supported by Monte Carlo-type simulations which interrogate the effects of measurement uncertainty. Of the nine tested fuels, three fuels are “Tier III” fuel blends, meaning that they are blends of molecules which have passed two levels of screening, and have been evaluated to be ready for tests in research engines. These molecules have been blended into a four-component gasoline surrogate at varying volume fractions in order to achieve a RON rating of 98. The molecules under consideration are isobutanol, 2-butanol, and diisobutylene (which is a mixture of two isomers of octene). The remaining six fuels were research-grade gasolines of varying formulations.
Journal Article

The Impacts of Pd in BEA Zeolite on Decreasing Cold-Start NMOG Emission of an E85 Fuel Vehicle

2018-10-25
Abstract In the development of hydrocarbon (HC) traps for E85 fuel vehicle emission control, the addition of palladium (Pd) to BEA zeolite was studied for trapping and decreasing cold-start ethanol emissions. BEA zeolite after a laboratory aging at 750°C for 25 hours released nearly all of the trapped ethanol as unconverted ethanol at low temperature, and some ethene was released at a higher temperature by a dehydration reaction. The addition of Pd to BEA zeolite showed a decrease in the release of unconverted ethanol emissions even after the lab aging. The release of methane (CH4), acetaldehyde (CH3CHO), carbon monoxide (CO), and CO2 from Pd-BEA zeolite during desorption (temperature programmed desorption (TPD)) demonstrated that multiple ethanol reaction mechanisms were involved including dehydrogenation and decomposition reactions.
Journal Article

Limitations of Monoolein in Simulating Water-in-Fuel Characteristics of EN590 Diesel Containing Biodiesel in Water Separation Testing

2018-10-18
Abstract In modern diesel fuel a proportion of biodiesel is blended with petro-diesel to reduce environmental impacts. However, it can adversely affect the operation of nonwoven coalescing filter media when separating emulsified water from diesel fuel. This can be due to factors such as increasing water content in the fuel, a reduction in interfacial tension (IFT) between the water and diesel, the formation of more stable emulsions, and the generation of smaller water droplets. Standard water/diesel separation test methods such as SAE J1488 and ISO 16332 use monoolein, a universal surface-active agent, to simulate the effects of biodiesel on the fuel properties as part of water separation efficiency studies. However, the extent to which diesel/monoolein and diesel/biodiesel blends are comparable needs to be elucidated if the underlying mechanisms affecting coalescence of very small water droplets in diesel fuel with a low IFT are to be understood.
Journal Article

Improvement in DCT Shaft Lubrication through CFD Method

2018-10-25
Abstract Dual-clutch transmission (DCT) output shaft 1 (OS1) mount position is higher than the transmission lubricant level. Needle bearings and idler gears on OS1-insufficient lubrication issues and the transmission lubrication system were investigated. In the design model, the transmission housing lubrication channel and oil guide component design were studied. For numerical analysis, the STAR-CCM+ software was used to simulate transmission internal complex oil-gas multiphase transient flow morphology that monitored the four bore oil churning volumes of OS1. Finally, lubrication test results affirm simulation predictions that idler gears, needle bearings, and synchronizer rings on OS1 obtain sufficient lubrication provided that a reliable method to inspect lubrication design functions is available.
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

An Approach for Heavy-Duty Vehicle-Level Engine Brake Performance Evaluation

2019-01-08
Abstract An innovative analysis approach to evaluate heavy-duty vehicle downhill engine brake performance was developed. The vehicle model developed with GT-Drive simulates vehicle downhill control speeds with different engine brake retarding powers, transmission gears, and vehicle weights at sea level or high altitude. The outputs are then used to construct multi-factor parametric design charts. The charts can be used to analyze the vehicle-level engine brake capabilities or compare braking performance difference between different engine brake configurations to quantify the risk of engine retarding power deficiency at both sea level and high altitude downhill driving conditions.
Journal Article

Development of a Standard Testing Method for Vehicle Cabin Air Quality Index

2019-05-20
Abstract Vehicle cabin air quality depends on various parameters such as number of passengers, fan speed, and vehicle speed. In addition to controlling the temperature inside the vehicle, HVAC control system has evolved to improve cabin air quality as well. However, there is no standard test method to ensure reliable and repeatable comparison among different cars. The current study defined Cabin Air Quality Index (CAQI) and proposed a test method to determine CAQI. CAQIparticles showed dependence on the choice of metrics among particle number (PN), particle surface area (PS), and particle mass (PM). CAQIparticles is less than 1 while CAQICO2 is larger than 1. The proposed test method is promising but needs further improvement for smaller coefficient of variations (COVs).
Journal Article

Evaluation of a Robust Haptic Interface for Semi-Autonomous Vehicles

2019-05-15
Abstract The advent of steer-by-wire technologies has changed the driving paradigm for drivers and vehicle autonomy. Such technologies integrate electric motors to actuate the tire-road plus human-machine interfaces. Steer-by-wire vehicles can benefit from haptic concepts through the provision of tunable force feedback, coupled with nonlinear control, to introduce lane keeping and pathway following technologies that minimize and possibly eliminate driver actions. In this article, two vehicle haptic interfaces, including a robotic grip and a joystick, both of which are accompanied by nonlinear sliding mode control, have been developed and studied on a steer-by-wire platform integrated with a virtual reality driving environment. An operator-in-the-loop evaluation that included 30 human test subjects investigated these haptic steering interfaces over a prescribed series of driving maneuvers through real-time data logging and post-test questionnaires.
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.
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