Search Results

In this paper, we present a design and control methodology of an innovated structure of switching synchronous motor. This control strategy is based on the pulse width modulation technique imposing currents sum of a continuous value and a value having a shape varying in phase opposition with respect to the variation of the inductances. This control technology can greatly reduce vibration of the entire system due to the strong fluctuation of the torque developed by the engine, generally characterizing switching synchronous motors. A systemic design and modelling program is developed. This program is validated following the implementation and the simulation of the control model in the simulation environment Matlab-Simulink. Simulation results are with good scientific level and encourage subsequently the industrialization of the global system.

A 10 KWe dual-mode space power system concept has been identified which is based on INEL's Small Externally-fueled Heat Pipe Thermionic Reactor (SEHPTR) concept. This power system will enhance user capabilities by providing reliable electric power and by providing two propulsion systems; electric power for an arc-jet electric propulsion system and direct thrust by heating hydrogen propellant inside the reactor. The low thrust electric thrusters allow efficient station keeping and long-term maneuvering. The direct thrust capability can provide tens of pounds of thrust at a specific impulse of around 730 seconds for maneuvers that must be performed more rapidly. The direct thrust allows the nuclear power system to move a payload from Low Earth Orbit (LEO) to Geosynchronous Earth Orbit (GEO) in less than one month using approximately half the propellant of a cryogenic chemical stage.

Aerospace structures manufacturers find themselves frequently engaged in large-scale 3D metrology operations, conducting precision measurements over a volume expressed in meters or tens of meters. Such measurements are often done by metrologists or other measurement experts and may be done in a somewhat ad-hoc fashion, i.e., executed in the most appropriate method according to the lights of the individual conducting the measurement. This approach is certainly flexible but there are arguments for invoking a more rigorous process. Production processes, in particular, demand an automated process for all such “routine” measurements. Automated metrology offers a number of advantages including enabling data configuration management, de-skilling of operation, real time input data error checking, enforcement of standards, consistent process execution and automated data archiving. It also reduces training, setup time, data manipulation and analysis time and improves reporting.

This SAE Aerospace Information Report (AIR) describes procedures for use in the field to determine if 115/200 Volt, 400 Hz aircraft external electrical power connectors are excessively worn, which may result in the inability of the external power plug to be retained, intermittent electrical performance and arcing.

This SAE Aerospace Information Report (AIR) describes procedures for use in the field to determine if 115/200 Volt, 400 Hz aircraft external electrical power connectors are excessively worn, which may result in the inability of the external power plug to be retained, intermittent electrical performance and arcing.

An efficient design of the gearbox is crucial for the expected performance of the vehicle both in terms of life and NVH. This involves design and analysis of gears, shafts, bearings, gear layout and speed ratios. Conventionally gears, shafts and bearings are designed and analysed independently. When the design of these parts change, their effect on related parts is estimated separately, leading to loss of time. Alternately, an integrated approach through simulation is adopted for the new two wheeler's gearbox by modeling on Romax designer software, consisting of shafts, bearings and gears. For the target load cycle, gear and bearing lives, shaft deflections and stresses are estimated. While the targets for stresses, deflections and lives are set logically and with experience, these are also compared with those of reference vehicle by creating and analysing reference gearbox model.

This paper summarizes the techniques and guidelines which were used to reduce the driver perceived noise level of a 145-210 HP series of agricultural tractors. Graphs of case study test results and comments on subjective noise quality are provided to guide the acoustic novice through the complexities of the vehicle sound environment in a methodical problem solving format.

Transfer path analysis is a powerful tool to support the vehicle NVH development. On the one hand it is a fast method to gain an overview of the complex interplay in the vehicle noise generation process. On the other hand it can be used to identify critical noise paths and vehicle components responsible for specific noise phenomena. FEV has developed several tools, which are adapted to the considered noise phenomena: Powertrain induced interior noise and vibration is analyzed by VINS (Vehicle Interior Noise Simulation), which allows the deduction of improvement measures fast enough for application in the accelerated vehicle development process. Further on vehicle/powertrain combinations not realized in hardware can be evaluated by virtual installation of the powertrain in the vehicle, which is especially interesting in the context of engine downsizing from four to three or six to four cylinders.

In a running engine, various impacts are excitation sources for structural vibrations and engine noises. Engine noises are classified, depending on their excitation sources, into the combustion noise, the combustion induced mechanical noise and the mechanical noise. It is difficult to measure such noises separately because some impacts occur closely in time and space. In this paper, a transient noise generation model of an engine was proposed considering vibration and its damping of engine structure. The present model was verified through the single explosion excitation experiment for a stationary engine. Using the noise generation model, the combustion noise was separated from the total noise radiating from a running four-stroke gasoline engine for motorcycles. It was found that the combustion noise had larger power at lower frequencies than higher frequencies. However, its contribution to the total engine noise was relatively small.

A first attempt to study civil aircraft operations comprehensively, prior to having the airplane, occurred before the initial operation of U.S. subsonic jets. One airline carried out a manual-simulated “paper jet” operation lasting fifteen months. Today, computerized simulation of machines, methods, and operations has become commonplace, and replaces the slide rule and tedious day-by-day inputs of aircraft operational criteria. Computerized simulations are also applied to every aspect of the SST design and operations. These are important, but the results being should be used with caution and judgement.

This paper presents a summary of body structural analysis applied to the 1989 Suzuki Sidekick/Geo Tracker at various stages of development and design. The structure analysis techniques were applied previously to rigidity, vibration, strength, crashworthiness and optimization. The studies confirm that the CAE technique for body structure analysis is more beneficial if it is utilized in the earlier structure development stages particularly for vibration and crashworthiness. Through the extensive use of the structural analysis technique in conjunction with the experiment, the design concept of the Sidekick/Tracker body has been optimized to a most extent.

General Motors Powertrain Group (GMPTG) has developed an all new small block V8 engine, designated LS1, for introduction into the 1997 Corvette. This engine was designed to meet both customer requirements and competitive challenges while also meeting the ever increasing legislated requirements of emissions and fuel economy. This 5.7L V8 provides increased power and torque while delivering higher fuel economy. In addition, improvements in both QRD and NVH characteristics were made while meeting packaging constraints and achieving significant mass reductions.

A student team from Minnesota State University, Mankato's Automotive Engineering Technology program entered the Clean Snowmobile Challenge 2000. A 1998 Polaris Indy Trail was converted to indirect fuel injection running on a computer controlled closed loop fuel system. Also chassis, exhaust, and hood design modifications were made. The snowmobile was designed to compete in eight events. These events included acceleration, emissions, hill climb, cold start, noise, fuel economy/range, handling/driveability, and static display. The snowmobile modifications involved every aspect of the snowmobile with special emphasis on emissions and noise. Laboratory testing led to the final design. This paper details the modifications and test results.

The Cardinal is a Super Short Takeoff and Landing (SSTOL) aircraft, which is designed to fulfill the desire for center-city to center-city travel by utilizing river “barges” for short takeoffs and landings to avoid construction of new runways or heliports. In addition, the Cardinal will fulfill the needs of the U.S. Navy for a Carrier On-board Delivery (COD) aircraft to replace the C-2 Greyhound. Design requirements for the Cardinal included a takeoff ground roll of 300 ft, a landing ground roll of 400 ft, cruise at 350 knots with a range of up to 1500 nm with reserves, payload of 24 passengers and baggage for a commercial version or a military version with a 10,000 lb payload, capable of carrying two GE F110 engines for the F-14D, and a spot factor requirement of 60 feet by 29 feet.

Without engine noise, the cabin of an electric vehicle is quiet, but on the other hand, it becomes easy to perceive refrigerant-induced noise in the automotive air-conditioning (A/C) system. When determining the A/C system at the design stage, it is crucial to verify whether refrigerant-induced noise occurs in the system or not before the real A/C systems are made. If refrigerant-induced noise almost never occurs during the design stage, it is difficult to evaluate by vehicle testing at the development stage. This paper presents a 1D modeling methodology for the assessment of refrigerant-induced noise such as self-excitation noise generated by pressure pulsation through the thermal expansion valve (TXV). The GT-SUITE commercial code was used to develop a refrigerant cycle model consisting of a compressor, condenser, evaporator, TXV and the connecting pipe network.

Most of current jet aircraft circulate fuel on the airframe to match heat loads with available heat sink. The demands for thermal management in wide range of air vehicle systems are growing rapidly along with the increased mission power, vehicle survivability, flight speeds, and so on. With improved aircraft performance and growth of heat load created by Aircraft Mounted Accessory Drive (AMAD) system and hydraulic system, effectively removing the large amount of heat load on the aircraft is gaining crucial importance. Fuel is becoming heat transfer fluid of choice for aircraft thermal management since it offers improved heat transfer characteristics and offers fewer system penalties than air. In the scope of this paper, an AMESim model is built which includes airframe fuel and hydraulic systems with AMAD gearbox of a jet trainer aircraft. The integrated model will be evaluated for thermal performance.