Vehicle Passenger Compartment Research Articles

Adiabatic Flow Simulation in an Air-Conditioned Vehicle Passenger Compartment

Dispersion and flow of air in passenger compartments of vehicles are important to assure a comfortable environment for passengers, driver concentration and safe driving conditions. The article describes numerical adiabatic flow simulations for the „mute“, an electric car. Air streams in its passenger compartment were simulated; air velocities were compared while using different turbulence models. The turbulence models were selected upon being screened for best-suiting characteristics. The eddy-viscosity standard, RNG k-e and SST k-ω models were used. Near-wall approaches (standard wall functions, scalable wall functions and enhanced wall treatment) were checked against a test case from “European Research Community on Flow, Turbulence and Combustion to determine the best choice for „mute“ passenger compartment air velocity simulations. (Received in March 2013, accepted in September 2013. This paper was with the authors 3 months for 2 revisions.)

Influencing Factors and Sensitivity Analysis of Occupant Impact Injury in Passenger Compartment

Objective: The study reported in this article addressed the influence of each factor (impact acceleration, table height h, table to seat distance l 1, interseat distance l 2, table contact stiffness k 1, seat contact stiffness k 2, etc.) on the extent of occupant impact injury in a railway vehicle secondary collision. Methods: The vehicle's passenger compartment–occupant coupling model was established using proprietary software (MADYMO). The simulated occupant was MADYMO's validated Hybrid III 50th percentile dummy model, and the vehicle's passenger compartment model included the floor surface, side wall, seat (with cushion), backrest, and table. The floor surface and side wall were modeled as flat surfaces; the seat (with its cushion), backrest, and table were modeled as ellipsoids. Some 25 samples were selected for numerical simulation based on a 2-factor, 5-level, full-factorial experimental design: the response surface method (RSM) was applied to fit the mapping relationship between the occupant's injury parameters (head injury criterion [HIC] and thoracic cumulative 3-ms injury criterion [TC3ms]) and other multi-influence factors. Results: Taking the seat–table structure model and seat–seat structure model as examples, the influence of each factor on the extent of the passenger compartment occupant's impact injury was assessed from the basis of traditional passenger compartment configurations found on Chinese trains. The sensitivity analysis of occupant injury parameters on these influence factors was carried out to determine the extent of the influence of each factor on each impact injury parameter. Conclusions: The response surfaces of the occupant's injury parameters (HIC and TC3ms), and changes therein as the system's variables were altered showed that impact injury parameters and change thereto could be described intuitively and qualitatively. Some meaningful conclusions were obtained through the sensitivity analysis of occupant injury parameters to changes in these influence factors. The research offered a guideline for the design and manufacture of a train's passenger compartment structure. Supplemental materials are available for this article. Go to the publisher's online edition of Traffic Injury Prevention to view the supplemental file.

Acoustic Parts in Vehicle Sound Transmission Loss Test Method Research

The sound transmission loss (STL) of the acoustic parts in the vehicle was proposed to be computed using the Sound Pressure Level measured at the several locations inside the vehicle and the transmitted Sound Intensity Level on the vehicles exterior panel, which the acoustic treated vehicle passenger compartment is assumed as a small reverberation room. The necessary parts retrofits and acoustic treatments for Sound transmission loss tests of the acoustic parts in the vehicle were listed. The values of the appropriate number and positions of the loud speakers, microphones and sound intensity probes for Sound transmission loss of the acoustic parts in the vehicle were recommended. The in vehicle sound transmission loss tests of the acoustic parts such as the doors, carpets, wheel house etc. were achieved in the semi-anechoic room. Based on the door system, the correlation work has been done among the methods of the proposed in vehicle STL test, the reverberation - semi-anechoic chamber buck STL test and SEA analysis.

Observations of Gunshot Residue Associated with Police Officers, Their Equipment, and Their Vehicles

The three studies described in this paper were undertaken to determine whether gunshot residue (GSR) particles could be detected on police officers, on their equipment, in police vehicles, and on civilians who work in a police environment. Three Toronto area municipal police services participated in this research. The first study involved collecting samples from patrol and plainclothes officers and their equipment. The second study compared observations for forensic identification officers and civilians working in the same facility. The prevalence of GSR particles in the rear passenger compartment of police vehicles was examined in the third study. For each study, tapelift samples were collected and analyzed by scanning electron microscopy/energy dispersive X-ray analysis (SEM/EDX). At least one GSR particle was detected on the hands of 60 percent of the patrol and plainclothes officers sampled and on 24 percent of the police equipment sampled. Twenty-five percent of the forensic identification officers sampled had at least one GSR particle on their hands. No GSR particles were found on any of the civilians sampled. Only two of 18 vehicles sampled were found to have any GSR particles present and, in each of these two incidences, a single particle was detected. The presence of GSR particles on police officers' hands, equipment, and vehicles demonstrates that these are potential sources of particles available for transfer.

Measurement of Airflow Resistivity Variation Due to Temperature and Its Impact on Simulated Sound Absorption Inside a Vehicle's Passenger Compartment

Measurement of Airflow Resistivity Variation Due to Temperature and Its Impact on Simulated Sound Absorption Inside a Vehicle's Passenger Compartment

A Survey of Sound Quality in the United States Automotive Industry

A Survey of Sound Quality in the United States Automotive Industry

An edge-based smoothed finite element method (ES-FEM) for analyzing three-dimensional acoustic problems

It is well-known that one key issue of solving the Helmholtz equation using finite element method (FEM) is the accuracy deterioration in the solution with increasing wave number due to the “numerical dispersion error”. Such a numerical dispersion error is essentially caused by the “overly-stiff” nature of the FEM model. To overcome this problem, this paper presents an edge-based smoothed finite element method (ES-FEM) for analyzing acoustic problems using linear triangular and tetrahedron elements that can be generated automatically, respectively, for complicated two-dimensional and three-dimensional domains. The discretized linear system equations for ES-FEM are established using the smoothed Galerkin weak form with smoothing domains associated with the edges of the triangles or surfaces of the tetrahedrons. The edge-based gradient smoothing operation provides proper softening effect, makes the ES-FEM model much softer than the “overly-stiff” FEM model and hence significantly reduces the numerical dispersion error. Numerical examples, including a 2D problem of acoustic pressure distribution in a vehicle passenger compartment and a 3D problem about the acoustic pressure distribution in an engine chamber, have been studied using the present ES-FEM. The results demonstrate that the ES-FEM possesses the following advantages compared with the standard FEM using the same meshes. First, ES-FEM achieves similar convergence rate but better accuracy especially at high frequency. Second, ES-FEM is less sensitive to the mesh distortion, meaning that the quality of mesh has less effect on the solution of ES-FEM. Third, it works well for triangular types of meshes, and thus for the problems with complicated geometry.

차실내 Defrost 노즐 분류의 충돌각 변화에 따른 유동특성에 관한 실험적 연구

The flow characteristics with the impinging angles of defrost nozzle jet inside a commercial vehicle passenger compartment were investigated experimentally by using the two-dimensional duct-nozzle model. The shape of the nozzle contraction was designed according to the curved line of cubic equation to the vertical plan of the flow direction. The impinging angles, defined as the angle between nozzle axis and a vertical line to the windshield, were varied from the 0° to 80°. The mean velocity distributions, the half-widths, and the momentum distributions with the cases of both the free jet and the impinging jet onto the dummy windshield were measured. The impinging jet flows similarly with wall jet from X/b<SUB>o</SUB>=20, and the impinging angle has an effect on the half-width of the impinging jet. The momentum distributions onto the windshield increased with the increase of impinging angle, and then their inflection point was observed around the impinging angle of 60°.

Reducing Automotive Interior Noise with Natural Fiber Nonwoven Floor Covering Systems

Eliminating unwanted noise in passenger compartments of vehicles is important to automobile manufacturers. The ability to reduce noise inside the vehicle enhances the perceived value of the vehicle to the consumer, and offers a competitive advantage to the manufacturer. Several methods are presently employed to reduce noise and its sources, one of which uses sound-absorbing materials attached to various components such as floor-coverings, package trays, door panels, headliners and trunk liners. Natural fibers are noise-absorbing materials that are renewable and biodegradable, making them an effective choice for the automobile industry. Floor coverings using natural fibers (kenaf, jute, waste cotton, and flax) in blends with polypropylene (PP) and polyester (PET) were developed as carded needle-punched nonwovens. The acoustical absorption coefficients of these floor coverings, and of floor coverings in combination with an underpad (either a rebonded polyurethane foam, or a soft cotton nonwoven) were evaluated by ASTM E— 1050 in the frequency range of 100 to 3200 Hz. By stacking an underpad and a floor covering together, a floor covering system was created. The measurements demonstrated that each of the natural fiber-based nonwoven floor coverings contributed to noise reduction, e.g., coefficients = 0.54—0.81 at 3.2 kHz. Noise was significantly reduced with a floor covering system using either of the underpads. The most reduction occurred with a polyurethane pad; for example, for kenaf floor covering C20-1 the coefficients at 3.2 kHz were: 1.0 with polyurethane versus 0.81 with cotton pad.

Acoustic-Structural Resonances of Thin-Walled Structure—Gas Systems

This paper summarizes a theoretical study, which is a natural continuation of approximately 50 years of research in the field of acoustoelasticity. Recently, the researchers’ interest has been directed towards considering compressible fluid in contact with thin walled structures as it was found that the acoustic-structural coupling significantly changes the dynamic behavior of the system. Despite the interesting findings the main results still need additional, numerical, or experimental verification. The present work is intended to cast more light on the acoustic-structure coupling of light fluid-shell systems using a numerical approach, namely 3-D finite element (FE) modeling. Two different acoustoelastic systems are considered. The first system is a thin circular cylindrical shell containing light fluid in a coaxial annular duct and the second system is a thin-walled vehicle passenger compartment interacting with the enclosed cavity. Both systems are studied using ANSYS finite element code. The modeling involved shell finite elements for the structure and 3-D acoustic elements for the cavity. The 3-D FE modal analysis used produced results visualizing the complex picture of acoustic-structure coupling. It was confirmed that (1) in both fluid-elastic systems the strongest acoustic-structural coupling exists if the resonances of uncoupled acoustic and mechanical systems are close and (2) the nature of the acoustic-structural coupling is identical in the two cases studied. However, it was found that strong coupling between the thin-walled structure and the acoustic cavity exists in the vicinity of any uncoupled acoustic resonance. Thus, the coupled properties of the systems were found to be dominated by the uncoupled acoustic resonances. As the focus of this study is on the mode shapes of vibration, it was found that coupled acoustic-structure modes of vibration exist in the neighborhood of an uncoupled acoustic resonance, which means that the coupled system manifests a specific type of energy exchange. These modes were termed coupled “combined” modes to differentiate from the coupled component responses. It was also found that the coupled “combined” modes are clustered around a rigid-walled cavity mode, and any acoustic-structure resonance of a given group involves this particular uncoupled acoustic mode. In conclusion, it is shown that the acoustic-structure interaction causes the appearance of coupled “combined” modes not existing in the shell in vacuo or rigid-walled acoustic spectrum. It was found also that the subsystems preserve their capability of independent vibration responses, i.e., the response at the component modes is believed to be strong at their uncoupled frequencies.

Passenger Thermal Comfort in Vehicles - A Review

A comprehensive survey is presented of research studies regarding thermal comfort issues in the vehicle passenger compartment environment. The work is classified according to whether it is concerned with the passenger compartment environment or the condition of the passengers and their interaction with the compartment. The review includes factors associated with passenger compartment conditions, such as flow field and temperature field, which affect the thermal comfort of the occupants. The evolution of thermal comfort models is reviewed. Also included are various computational and empirical models for predicting physiological response and the sensation of thermal comfort in the non-uniform transient environment of a vehicle. The use of thermal manikins in these studies is also incorporated. Areas in which additional information is required are identified and comments are made regarding future research directions.

Vehicle Self-Pollution Intake Fraction: Children's Exposure to School Bus Emissions

Vehicle self-pollution occurs when a vehicle's emissions migrate to inside that vehicle's passenger compartment. This paper presents values fortwo new parameters: vehicle self-pollution intake fraction (iF(SP)), which is the total fraction of a vehicle's emissions inhaled by all people in the vehicle, and vehicle self-pollution individual intake fraction (iF1SP), which is the fraction of a vehicle's emissions inhaled by an individual in the vehicle. We use results from tracer-gas experiments in California's South Coast Air Basin (SoCAB) to quantify students' iF(SP) and iF1SP for school bus emissions. Six buses were studied during nine runs with windows open and seven runs with windows closed. Reported iF(SP) values (units: per million; min = 10, max = 94, mean = 27) indicate that the total mass of a bus' exhaust inhaled by students commuting on it is comparable in magnitude to the total mass of that bus' exhaust inhaled by all other people in the SoCAB. Reported iF1SP values (units: per million; min = 0.2, max = 2.4, mean = 0.7) indicate that average per capita inhalation of emissions from any single bus is 10(5)-10(6) times greater for a student on that school bus than for a typical resident in the SoCAB. Vehicle self-pollution rate varies with bus window position (open or closed) and bus manufacture year. Our results can be used to develop cost-effective strategies to reduce children's exposure to school bus emissions. Our results indicate, for example, that even if emission reductions were many times more expensive per gram emitted for school buses than for an average vehicle, it would still be less expensive per gram inhaled by a student to reduce emissions from school buses than from an average vehicle.

Heat related deaths to young children in parked cars: an analysis of 171 fatalities in the United States, 1995–2002

Objective: To describe the circumstances surrounding heat related deaths to young children in passenger compartments of motor vehicles. Methods: Cases of heat related deaths to children aged ⩽5 years confined...

Ignition performance of new and used motor vehicle upholstery fabrics

This paper examines the standards for fire safety in transport systems and in particular the test method for the flammability of materials within passenger compartments of motor vehicles. The paper compares data from ignition tests conducted in the cone calorimeter and the FIST apparatus with tests conducted using the FMVSS 302 horizontal flame spread apparatus. Ten materials were selected as representative of those used as seat coverings of private and commercial passenger vehicles. The time to ignition of new and used materials subject to exposure heat fluxes between 20 kW/m2 and 40 kW/m2 was measured. The results from the ignition tests were analysed using thermally thick and thermally thin theoretical models. The critical heat flux for sustained piloted ignition was determined from the time to ignition data using the thermally thin approach. Derived ignition temperatures from both the thermally thick and thermally thin methods were compared with measurements using a thermocouple attached to the back surface of materials in selected tests. The flame spread rates in the FMVSS 302 apparatus were determined and a comparison was made between the performance of the materials in the flame spread apparatus, the cone calorimeter and the FIST. The results suggests that a critical heat flux criterion could be used to provide an equivalent pass/fail performance requirement to that specified by the horizontal flame spread test although further testing is needed to support this. Copyright © 2004 John Wiley & Sons, Ltd.

Measurements of Tyre/Road Noise and of Acoustical Properties of Porous Road Surfaces

The three main noise sources in modern cars and trucks are tyre/road interaction, wind turbulence, and the power plant. The power unit noise is composed of contributions from the fan, engine, exhaust, and transmission. In addition, the engine noise contains contributions from the injection system, intake, and cylinder block. Noise is of course a problem both inside the passenger compartments (interior noise) of vehicles and in residential areas near to the highway on which the vehicles are traveling (exterior noise). In most modern automobiles, the engine and exhaust noise have been sufficiently suppressed so that they are no longer the dominant interior or exterior noise sources. On heavy trucks, the engine is normally a diesel, and the suppression of its noise is more difficult. With vehicle noise, regulations are mostly concerned with exterior noise of vehicles, and this paper will consider mostly the exterior noise. Of course, if the exterior noise is reduced, the interior noise is normally reduced as well, although the relationship may not be quite linear. With modern well designed automobiles, the exterior noise is dominated by tyre noise at almost all speeds, even under accelerating conditions, except for acceleration in the first and second gears. With trucks, however, at speeds up to about 70 km/h, engine and exhaust noise is dominant under accelerating conditions. But above this speed, tyre noise becomes equally as important as engine, exhaust, and other power unit related noise sources, particularly as far as the exterior noise is concerned. This fact has been observed experimentally, and it has been found that similar trends exist for the exterior noise of a wide variety of manufactured vehicles and that the exterior noise of automobiles is significantly less than that of heavy trucks by almost 15 dB at low speed and by almost 10 dB at medium to high speed. One can conclude from the previous discussion that much of the exterior noise emitted from modern cars and trucks, particularly at medium to high speeds, is caused by tyre/road interaction noise. Of course, the frequency content of noise as well as its magnitude is very important. It has been observed that for automobiles travelling at medium to high speeds, the A-weighted noise peaks at about 1000 Hz, while for light and heavy trucks, the annoying noise peaks at a frequency closer to 1200 to 1600 Hz. In addition, it has been shown that the A-weighted exterior sound levels emitted by passenger cars and light and heavy trucks has not changed very much over time. This is probably because the power of automobiles has increased in many countries, particularly in the USA, and it is has been

Analysis of MRI patterns aids prediction of progression in X-linked adrenoleukodystrophy.

X-linked adrenoleukodystrophy (X-ALD) has variants with widely different outcomes, hampering clinical counseling and evaluation of therapies. To evaluate the degree to which MRI patterns can predict lesion progression. Two hundred six boys and men with cerebral X-ALD (median age 12.2 years, mean age 18.5 years, age range 1.7 to 73.8 years) were studied. In 140 individuals, follow-up MRI were available. Data after bone marrow transplantation (BMT) were excluded. The patterns of MRI abnormalities were subdivided into five groups based on the anatomic location of the initial T2 signal hyperintensity (pattern 1: parieto-occipital white matter, pattern 2: frontal white matter, pattern 3: corticospinal tract, pattern 4: cerebellar white matter, pattern 5: concomitant parieto-occipital and frontal white matter). The X-ALD MRI Severity Scale, a 34-point scale previously described, was used in the analysis. Pattern 1 patients had rapid progression if contrast enhancement was present and if the MRI abnormality manifested at an early age. The latter was also true for pattern 2 patients. Based on these variables, predictive formulas were constructed for these two patterns using multiple regressions. MRI progression was much slower in pattern 3 and 4 patients, whereas in the few pattern 5 patients, it was more rapid than in any other of the patterns. Patterns 1 and 5 occurred mainly in childhood, patterns 2 and 4 in adolescence, and pattern 3 in adults. MRI progression in X-ALD depends on patient age, initial MRI Severity Scale score, and anatomic location of the lesion. When used in combination, these data aid the prediction of disease course and the selection of patients for BMT.

Evaluation of recursive PIV algorithm with correlation based correction method using various flow images

The hierarchical recursive local-correlation PIV algorithm with CBC (correlation based correction) method was employed to increase the spatial resolution of PIV results and to reduce error vectors. The performance of this new PIV algorithm was tested using synthetic images, PIV standard images of Visualization Society of Japan, real flows including ventilation flow inside a vehicle passenger compartment and wake behind a circular cylinder with riblet surface. As a result, most spurious vectors were suppressed by employing the CBC method, the hierarchical recursive correlation algorithm improved the sub-pixel accuracy of PIV results by decreasing the interrogation window size and increased spatial resolution significantly. However, with recursively decreasing of interrogation window size, the SNR (signal-to-noise ratio) in the correlation plane was decreased and number of spurious vectors was increased. Therefore, compromised determination of optimal interrogation window size is required for given flow images, the performance of recursive algorithm is also discussed from a viewpoint of recovery ratio and error ratio in the paper.

Design and simulation of an energy absorbing underride guard for heavy vehicle rear-end impacts

Recent passenger car-heavy vehicle rear-end crashes demonstrate the importance of rear underride guard designs for heavy vehicle applications. Currently specified rear underride guards have many shortcomings, such as structural strength and energy dissipation capacity, clearance from ground, and other design aspects. As a result of these inadequacies in underride-guard design, many lives are lost every year when passenger cars slide underneath heavier vehicles. In this study, design modifications to an underride guard that minimally complies with the requirements contained in FMVSS 223/224 are evaluated. A previously performed crash test on the guard using a compact passenger car demonstrated the potential for excessive vehicle underride and passenger compartment intrusion problems. After the full-scale crash test, a detailed finite-element study is performed to investigate the shortcomings of the design. The accuracy of the underride guard model is partially validated using both a quasi-static and a full-scale crash test. After the validation, the guard is modified to improve its structural behaviour and energy-dissipation capacity. Four crash-test simulations are performed on the modified guard model to verify its effectiveness in energy dissipation and preventing intrusion into the passenger compartment. In these simulations, two vehicle speeds of 48 km/h and 56 km/h and two impact positions of 0% and 50% offsets are used to fully verify the acceptability of the modified guard model. Simulation results show that the modified rear underride guard performs much better than the original design. The guard dissipated a significant amount of the impacting vehicle's energy and showed no potential for passenger-compartment intrusion in any simulation. The deceleration of the vehicle was also within acceptable limits. Based on these results, it can be concluded that the improved guard performed well and the implementation of this particular underride guard on heavy vehicles looks promising.

Visualizing acoustic field inside a passenger vehicle compartment

The objective of this study is to examine the effectiveness of the HELS method [S. F. Wu and J. Yu, J. Acoust. Am. 104, 2054–2060 (1998); S. F. Wu, ibid. 107, 2511–2522 (2000)] in visualizing the areas that are prone to noise transmission into a full-size vehicle passenger compartment due to engine, powertrain system, tires, and wind excitations. The input to the HELS formulation is the acoustic pressure measured inside the compartment. No vehicle geometry and dimensions are necessary. The optimum number of expansion functions is determined by minimizing the sum of the squared errors with respect to the measured data. Once the HELS formulation is established, the acoustic pressure anywhere including the vehicle interior surface can be determined. The normal component of the surface velocity can be reconstructed in a similar manner. Once these quantities are specified, the normal component of the time-averaged acoustic intensity and acoustic energy flow inside a vehicle passenger compartment can be visualized. This three-dimensional acoustic image can provide valuable insight into vehicle interior noise reduction. The effects of number and locations of measurements on the accuracy of reconstruction are investigated. [Work supported by the Daimler-Chryster Challenge Fund.]

Prediction of vehicle passenger compartment noise due to turbulent flow excitation

An engineering computer model is developed for estimating noise transmission into a vehicle passenger compartment, given the characteristic dimensions of the vehicle and turbulent flow excitation. In this model, the effects of window offset and leakage, and those of power spectral densities due to separated and reattached flows are taken into account. Empirical formulations are developed to estimate the reattachment line and the power spectral densities of separated and attached flows. The effect of leakage is accounted for by a correction factor. The computer model thus developed is validated on a greenhouse vehicle model. Experiments are conducted in a wind tunnel at the Chrysler Technology Center. Pressure fluctuations due to separated and attached flows on the side window are measured and compared with the calculated values. These pressure fluctuations are taken as input to a computer program, called VibroAcoustic Payload Environment Prediction System based on Statistical Energy Analysis, to calculate the noise spectrum, given the A-pillar angle, window size and offset, vehicle yaw angle, and wind speed. The predicted noise spectra inside the passenger compartment are compared with the measured ones under various flow speeds. Satisfactory agreements are obtained in all cases. [Work supported by a Chrysler Challenge Fund.]