Search Results

Headlights manufactures in the automotive industry make a large usage of polymers and plastic materials addressing important issues such as thermal stress control and water condensation on the inner surfaces of the headlamp as important factors for headlight design. In this paper, an innovative simulation methodology to calculate thermal distribution in automotive headlights is illustrated. With this method radiation is accurately calculated by means of a dedicated software whereas conductive and convective heat transfer is calculated by means of a general CFD code. A condensation model has also been developed and utilized with the CFD code to investigate the effect of forced convection flow through the headlight vents on water film evaporation. CFD results have been validated against measured headlight wall temperatures and flow velocities showing an encouraging degree of agreement.

Flow generated acoustic sources are of significant import for automotive applications since perception of noise is a critical customer satisfaction issue. High temperature acoustic sources known as thermo-acoustics such as those occurring inside an exhaust system of a vehicle, an important subset of acoustic sources, is the subject of the investigation. In this article, we study a Rijke tube configuration that consists of a vertical and hollow cylindrical tube open at both ends where sound is generated by buoyancy driven flow as a result of a heated wire gauze placed in the bottom half of the tube. This configuration captures the essence of the thermo-acoustic phenomena and was investigated both numerically and experimentally and good agreement was observed between the two.

Current plastic intake manifolds are manufactured using the injection molding process. In this paper, thermoforming is explored as an alternative to injection molding for making intake manifold shells, which can then be joined by one of the welding techniques used for thermoplastic materials. The investigation reported here includes press-forming experiments of a simple bowl shaped shell and subsequent welding experiments to join these shells.

This paper describes and analyzes the results of investigations of application of heavy alcohols as an ingredient of diesel fuel. Three different mi xtures of butanol (as heavy alcohol), rape oil (as vegetable oil) and conventional diesel fuel (this mixture was called the biomixdiesel-BMD) were tested using a Perkins engine on a test bed. Contrary to existing experiences both the maximum power output and the maximum torque of the engine were higher in the whole range of the speed of the engine crankshaft when the engine biomixdiesel (BMD) was reinforced. The addition of the component biomix to fuel influenced the specific fuel consumption. Generally, with the larger part of the biomix components the specific fuel consumption were higher. Also the engine power was higher and one should expect that in exploitation the specific fuel consumption should not increase. It is very important that this fuel could be used to reinforce old, already existing and the future diesel engines.

One of the main customer requirements for passenger cars is a pleasant sound based on a low interior noise level. Because of the reduction of many single noise sources, tyre road noise is now becoming increasingly important. In this paper an efficient approach for investigation of tire road noise is presented. First based on coherence analysis the main noise transmission behaviors are identified. Relevant frequency ranges for structure borne noise and airborne noise can be determined. Additionally it’s possible to separate noise transmission coming from front or rear axle. With this preliminary analysis /1/ it’s possible to reduce the effort to the limit. Now for structure borne noise transmission as well as for airborne noise transmission the critical paths are identified via transfer path analysis (TPA). For the estimation of airborne noise paths two different methods are compared. First the relevant airborne noise transfer paths are estimated via matrix inversion method /2/.

Low interior noise levels in combination with a comfortable sound is an important task for passenger cars. Due to the reduction of many noise sources over the last decades, nowadays tire-road noise has become one of the dominant sources for the interior noise. Especially for manufactures of luxury cars, the reduction of tire-road noise is a big challenge and therefore a central part of NVH development. The knowledge of the noise transmission behavior based on the characteristics of the relevant sources is a fundamental of a modern NVH - development process. For tire-road noise the source characteristics can be described by wheel forces and radiated airborne noise. In combination with the related vehicle transfer functions it is possible to describe the noise transmission behavior in detail. A method for estimating wheel forces and radiated airborne noise is presented.

Tire traction performance is dependent on both the tire design and the road surface on which the tire is operated. Measurement of a tire's traction capabilities is indicative of the performance of the tire-road surface combination. Therefore, it is important that the surfaces used to evaluate tire traction capabilities react in a manner similar to those on which the tire will operate. This paper presents a method for categorizing road surface traction properties by evaluating the traction performance of road surfaces when tested with a series of special tires. Data are presented on a series of road surfaces and recommendations are made for traction test surface design.

This paper describes an investigation to find the root cause for the high torque output variation in a duo-servo park brake system. Six Sigma tools were used to analyze the available data and to set up a “Design of Experiments” (DoE). In addition FE-calculations were performed to investigate the influence of the parameters that could not be clearly identified by measurements.

The focus of this research is to perform a detailed investigation of the tradeoffs between mass, efficiency, service factor (SF), power factor (PF), and cost of commercially available induction machines (IMs). To support this effort, data from a large number of IMs is used to establish Pareto-optimal fronts between these competing objectives. From the Pareto-optimal fronts, relatively straightforward models are formulated for the mass versus loss, cost versus loss, SF versus mass, PF versus cost. Parameters of the models are obtained using a genetic algorithm (GA).

This paper presents a control system development for a yaw motion control of a vehicle-trailer combination using the integrated control of active front steer (AFS) and differential brake (DB). A 21 degree of freedom (dof) vehicle-trailer combination model that represents a large SUV and a medium one-axle trailer has been developed for this study. A model reference sliding mode controller (MRSMC) has been developed to generate the desired yaw moment. Based on the understanding of advantages and limitations of AFS and DB, a new integrated control algorithm was proposed. The simulation result shows that integrated control of AFS and DB can restrain the trailer's oscillation effectively and shows less longitudinal speed drop and higher stable margin compared to the DB activated only case while maintaining the yaw stability.

Natural wind, roadside obstacles, terrain roughness, and traffic influence the incident flow of a vehicle driven on public roads. These transient on-road conditions differ from the idealized statistical steady-state flow environment utilized in CFD simulations and wind tunnel experiments. To understand these transient on-road conditions better, measurements were performed on German public highways and on a test site. A compact car was equipped with a measurement system that is capable of determining the transient airflow around the vehicle and the vehicle’s actual driving state. This vehicle was driven several times on a predefined 200 km long route to investigate different traffic densities on public highways in southern Germany. During the tests the transient incident flow and pressure distribution on the vehicle surface were measured.

The use of low temperature combustion (LTC) modes has demonstrated abilities to lower diesel engine emissions while maintaining good fuel consumption. LTC is assumed to be a viable solution to assist in meeting stringent upcoming diesel engine emissions targets, particularly nitric oxides (NOx) and particulate matter (PM). However, LTC is currently limited to low engine loads and is not a feasible solution at higher loads on production engines. A mixed mode combustion strategy must be implemented to take advantage of the benefits offered from LTC at the low loads and speeds while switching to a conventional diesel combustion strategy at higher loads and speeds and thus allowing full range use of the engine under realistic driving conditions. Experiments were performed to characterize engine out emissions during transient engine operating conditions involving LTC combustion strategies.

The calibration of the electronic throttle unit and the pedal unit was made. Based on it, an electronic control system of electronic throttle was designed and installed on a 4G18 engine. Engine experiment was made especially for its transient working condition. Engine performance at transient working condition was investigated. The test results indicate that the optimum way of opening the throttle valve is to open the throttle valve to the target location at once, when 4G18 engine transit from 2000r/min to 3000r/min without load. And its optimum calibration for the electronic throttle control unit is made based on the test results. The control system, the experiment, the test results and the calibration were introduced in this paper.

Sublimators have been used for heat rejection in a variety of space applications including the Apollo Lunar Module and the Extravehicular Mobility Unit (EMU). Sublimators typically operate with steady-state feedwater utilization at or near 100%. However, sublimators are currently being considered to operate in a cyclical topping mode during low lunar orbit for Altair and possibly Orion, which represents a new mode of operation. This paper will investigate the feedwater utilization when a sublimator is used in this nontraditional manner. This paper includes testing efforts to date to investigate the Orbit-Averaged Feedwater Utilization (OAFU) for a sublimator.

A technology demonstration propylene Loop Heat Pipe (LHP) has been tested extensively in support of the implementation of this two-phase thermal control technology on NASA’s Earth Observing System (EOS) Tropospheric Emission Spectrometer (TES) instrument. This cryogenic instrument is being developed at the Jet Propulsion Laboratory (JPL) for NASA. This paper reports on the transient characterization testing results showing low frequency temperature oscillations. Steady state performance and model correlation results can be found elsewhere. Results for transient startup and shutdown are also reported elsewhere. In space applications, when LHPs are used for thermal control, the power dissipation components are typically of large mass and may operate over a wide range of power dissipations; there is a concern that the LHP evaporator may see temperature oscillations at low powers and over some temperature range.

This work details two approaches for evaluating transmission warming technology: experimental dynamometer testing and development of a simplified transmission efficiency model to quantify effects under varied real world ambient and driving conditions. Two vehicles were used for this investigation: a 2013 Ford Taurus and a highly instrumented 2011 Ford Fusion (Taurus and Fusion). The Taurus included a production transmission warming system and was tested over hot and cold ambient temperatures with the transmission warming system enabled and disabled. A robot driver was used to minimize driver variability and increase repeatability. Additionally the instrumented Fusion was tested cold and with the transmission pre-heated prior to completing the test cycles. These data were used to develop a simplified thermally responsive transmission model to estimate effects of transmission warming in real world conditions.

Fourteen subsonic axisymmetric inlet models with various forebody contours and geometry parameters were tested in the NASA-Langley Research Center 16-foot transonic wind tunnel. Test Mach numbers ranged from 0.59 to 0.96. A mass flow control throttle (translating plug) allowed mass flow ratios from 0.23 to 0.92. Force and pressure data were acquired for all fourteen inlets, with and without external boundary layer transition strips (grit). The force balance was found to be defective after completion of the test. However, drag data were calculated from wake pressure rake data. Various inlet geometry effects on drag characteristics were analyzed. In particular, drag divergence Mach number was found to correlate with inlet thickness ratio. Experimental pressure and drag data were also compared with predictions from full potential transonic flow codes to verify their reliability and accuracy.

The objective of this study was to investigate potential for traumatic brain injuries (TBI) using a newly developed, geometrically detailed, finite element head model (FEHM) within the concept of a simulated injury monitor (SIMon). The new FEHM is comprised of several parts: cerebrum, cerebellum, falx, tentorium, combined pia-arachnoid complex (PAC) with cerebro-spinal fluid (CSF), ventricles, brainstem, and parasagittal blood vessels. The model's topology was derived from human computer tomography (CT) scans and then uniformly scaled such that the mass of the brain represents the mass of a 50th percentile male's brain (1.5 kg) with the total head mass of 4.5 kg. The topology of the model was then compared to the preliminary data on the average topology derived from Procrustes shape analysis of 59 individuals. Material properties of the various parts were assigned based on the latest experimental data.

This paper investigates the tire-road interaction for tires equipped with two different solid rubber material definitions within a Finite Element Analysis virtual environment, ESI PAMCRASH. A Mixed Service Drive truck tire sized 315/80R22.5 is designed with two different solid rubber material definitions: a legacy hyperelastic solid Mooney-Rivlin material definition and an Ogden hyperelastic solid material definition. The popular Mooney-Rivlin is a material definition for solid rubber simulation that is not built with element elimination and is not easily applicable to thermal applications. The Ogden hyperelastic material definition for rubber simulations allows for element destruction. Therefore, it is of interest and more suited for designing a tire model with wear and thermal capabilities.

In this study, whoosh noise phenomenon was investigated. This broad-band noise is revealed during full throttle run-up maneuvers at high gears between 1000 and 2200 rpm and also during sudden closure of throttle. To investigate the root cause of whoosh noise phenomenon, airborne source quantification (ASQ) method, structural and cavity modal analyses, and CFD analysis were used. Then, a so-called A-tube resonator was designed, manufactured in prototype level, and mounted to turbocharger outlet duct. Finally, a solution was obtained both objectively and subjectively.