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In the air conditioning system, flow-induced noise is very disturbing, including the noise generated in the expansion device and the heat exchangers. In the past few decades, most researches related to flow-induced noise focused on the relationship between the flow regimes near the expansion device and the amplitude of flow-induced noise when the measurements are not synched. In this paper, an experimental approach is used to explore the simultaneous relationships between flow-induced noise characteristics and flow regimes at the inlet of TXV of evaporators used in automobiles. A pumped R134a loop with microphones and transparent visualization sections is used to simulate the vapor compression system. Also, the paper evaluates the severity of flow-induced noise from not only the amplitude of noise but also the frequency of noise with a parameter called psychoacoustic annoyance (PA).

This article presents basic separation mechanisms with coalescing/impinging separators studied as the add-on to current popular centrifugal designs. The coalescence and impingement of oil on wire mesh and wave-plates are visualized and tested to investigate the impact of geometry and flow conditions on oil separation efficiency. Re-entrainment phenomenon is explained based on the mass balance. Oil mist flow at the swashplate reciprocating compressor discharge is quantified by video processing method to provide detailed information of the oil droplets. The physics behind oil separator is illustrated by visualization and measurement in this study, which gives useful guidelines for oil separator design and operation. The flow visualization shows the details of oil passing through different oil separation structures. Videos are quantified to provide information like droplet size distribution and liquid volume fraction.

A reconfigurable control system is an intelligent control system that detects faults within the system and adjusts its performance automatically to avoid mission failure, save lives, and reduce system maintenance costs. The concept was first successfully demonstrated by NASA between December 1989 and March 1990 on the F-15 flight control system (SRFCS), where software was integrated into the aircraft's digital flight control system to compensate for component loss by reconfiguring the remaining control loop. This was later adopted in the Boeing X-33. Other applications include modular robotics, reconfigurable computing structure, and reconfigurable helicopters. The motivation of this work is to test such control system designs for future long term space missions, more explicitly, the automation of life support systems.

The purpose this paper is to delineate why there exists a trade-off between biomechanical realism and algorithmic efficiency for human motion simulation models, and to illustrate how empirical human movement data and findings can be integrated with novel modeling techniques to overcome such a realism-efficiency tradeoff. We first review three major classes of biomechanical models for human motion simulation. The review of these models is woven together by a common fundamental problem of redundancy—kinematic and/or muscle redundancy. We describe how this problem is resolved in each class of models, and unveil how the trade-off arises, that is, how the computational demand associated with solving the problem is amplified as a model evolves from small scale to large scale, or from less realism to more realism.

Aircraft incidents and accidents in icing are often the result of degradation in performance and control. However, current ice sensors measure the amount of ice and not the effect on performance and control. No processed aircraft performance degradation information is available to the pilot. In this paper research is reported on a system to estimate aircraft performance and control changes due to ice, then use this information to automatically operate ice protection systems, provide aircraft envelope protection and, if icing is severe, adapt the flight controls. Key to such a safety system would be he proper communication to, and coordination with, the flight crew. This paper reviews the basic system concept, as well as the research conducted in three critical areas; aerodynamics and flight mechanics, aircraft control and identification, and human factors.

Past research on airfoil and wing aerodynamics in icing are reviewed. This review emphasizes the periods after the 1978 NASA Lewis workshop that initiated the modern icing research program at NASA and the current period after the 1994 ATR accident where aerodynamics research has been more aircraft safety focused. Research pre-1978 is also briefly reviewed. Following this review, our current knowledge of iced airfoil aerodynamics is presented from a flowfield-physics perspective. This section identifies four classes of ice accretions: roughness, rime ice, horn ice, and spanwise ridge ice. In these sections the key flowfield features such as flowfield separation and reattachment are reviewed and how these contribute to the known aerodynamic effects of these ice shapes. Finally Reynolds number and Mach number effects on iced-airfoil aerodynamics are briefly summarized.

This paper examines the feasibility of modifying an existing semi-trailer air suspension system to function as an anti-rollover system in addition to its normal suspension operation. The semi-trailer model used is a dynamic, two-dimensional system. The anti-rollover system controller is formulated using projective control theory. All other factors being equal, simulations show that use of the modified suspension system decreases the weight shift when the semi-trailer undergoes lateral acceleration. By decreasing weight shift, the modified suspension system decreases the possibility of rollover.

An efficient multi-component fuel droplet vaporization model has been developed in this work using discrete approach. The precise modeling of droplet vaporization process is divided into two parts: vapor-phase and liquid-phase sub-models. Temporal evolution of flow inside the droplet is considered to describe the transient behavior introduced by the slow diffusion process. In order to account for the internal circulation motion, surface regression and finite diffusion without actually resolving the spatial governing equations within the liquid phase, a set of ordinary differential equations is applied to describe the evolution of the non-uniform distributions of universal diffusional variables, i.e. temperature and species mass fraction. The differences between the droplet surface and bulk mean states are modeled by constructing a quasi-1D frame; the effect of the internal circulations is taken into consideration by using the effective diffusivity rather than physical diffusivity.

Virtual reality is an emerging technology with the potential for many engineering applications including machinery simulation. In this paper the writers describe the hardware and software components of a virtual reality system that simulates machinery. They detail the flow of information that occurs in this system and discuss the functioning of an existing system at the National Center for Supercomputing Applications (NCSA) located at the University of Illinois at Urbana-Champaign. Finally, they describe potential uses of virtual reality in product design, manufacturing, training and marketing.

Environmental concerns have obstructed development of new landfill sites making it essential to efficiently use currently available space. Finite element methods are evaluated for predicting densification by compactors with the intent of eventually optimizing vehicle design with respect to compaction. A geometrically non-linear, plane strain, quasistatic analysis is used to capture the effects of a single rigid wheel. Future work will include multiple wheels and successive passes, three-dimensional simulations, and realistic material characterization.

Neural networks are massively parallel computational models for knowledge representation and information processing. The capabilities of neural networks, namely learning, noise tolerance, adaptivity, and parallel structure make them good candidates for application to a wide range of engineering problems including diagnostics problems. The general approach in developing neural network based diagnostic methods is described through a case study. The development of an acoustic wayside train inspection system using neural networks is described. The study is aimed at developing a neural network based method for detection defective wheels from acoustic measurements. The actual signals recorded when a train passes a wayside station are used to develop a neural network based wheel defect detector and to study its performance. Signal averaging and scoring techniques are developed to improve the performance of the constructed neural inspection system.

In order to test and design vehicle systems it is often necessary to develop prototypes. A vehicle's steering system requires a qualitative analysis since it is difficult to quantify and measure subjective quantities such as the “feel” of a steering system. The virtual prototype system (VPS) provides an effective and flexible way of developing and testing the prototypes for qualitative testing. By creating a computer model of a vehicle's steering system using a dynamic simulation package and linking it to a virtual reality vehicle, a designer can drive the virtual prototype vehicle as if he or she were operating an actual vehicle.

Product engineers and product planners are routinely faced with trade-off decisions involving the cost of adding a product feature or modifying an existing feature versus its added value to the customer. The purpose of this paper is to assess the use of a personal computer (PC) for surveying respondents' willingness to pay (WTP) for four options - two-tone color, 4x4 drive, sporty trim package, and extended cab -- available on the base 1997 Ford F-150 truck. The results show that the respondents' stated WTP reflected the value of the options as determined from their prices and fraction of sales.

Air flow through the passages of a Chrysler LH platform ventilated brake rotor is measured. Modifications to the production rotor's vent inlet geometry are prototyped and measured in addition to the production rotor. Vent passage air flow is compared to existing correlations. The inlet modifications show significantly improved vent air flow, over the production rotor. The result improvement in heat transfer and rotor cooling is reported. These benefits in performance should be attainable at very low increases in production cost.

The feasibility of automatically detecting refrigerant charge loss in mobile air conditioning (MAC) systems by analyzing inexpensive dynamic measurements was studied. An indicator of the refrigerant inventory of the evaporator was developed. This measure, termed Time to Temperature Turning (TTT), is based on dynamic measurement of the evaporator outlet refrigerant temperature, and correlates strongly with charge level. TTT correlated well with clutch cycling behavior, a metric which is employed in current shop diagnostic practice to indicate refrigerant charge loss. Laboratory data were generated from a factorial experiment design on the following factors: condenser air inlet temperature, condenser air flow rate, evaporator air inlet temperature, compressor speed, and refrigerant charge. Experiments to date were conducted with a dry evaporator.

Service loading histories have the same general character for an individual route and the magnitudes vary from driver to driver. Both the magnitude and character of the loading history change from route to route and a linear scaling of one loading history does not characterize the variability of usage over a wide range of operating conditions. In this paper a technique for measuring and extrapolating cumulative exceedance diagrams to quantify the distribution of service loading in a vehicle is described. Monte Carlo simulations are coupled with the local stress strain approach for fatigue to obtain distributions of service loading. Fatigue life estimates based on the original loading histories are compared to those obtained from statistical descriptions of exceedance diagrams.

Control system design is one of the most critical issues for implementation of intelligent vehicle systems. Wide ranged fundamental research has been undertaken in this area and the safety issues of the fully automated vehicles are clearly recognized. Study of vehicle performance constrains is essential for a good understanding of this problem. This paper discusses safety issues of heavy-duty vehicles under automatic steering control. It focuses on the analysis of the effect of tire force saturation. Vehicle handling characteristics are also analyzed to improve understanding of the truck dynamics and control tasks. A simple differential brake control is formulated to show its effect of on reducing trailer swing.

This paper presents an experimental analysis of the performance of various control strategies applied to automotive air conditioning systems. A comparison of the performance of a thermal expansion valve (TEV) and an electronic expansion valve (EEV) over a vehicle drive cycle is presented. Improved superheat regulation and minor efficiency improvements are shown for the EEV control strategies. The efficiency benefits of continuous versus cycled compressor operation are presented, and a discussion of significant improvements in energy efficiency using compressor control is provided. Dual PID loops are shown to control evaporator outlet pressure while regulating superheat. The introduction of a static decoupler is shown to improve the performance of the dual PID loop controller. These control strategies allow for system capacity control, enabling continuous operation and achieving significant energy efficiency improvements.

High strength materials have desirable mechanical properties but often cannot be machined economically, which results in unacceptably high finished component cost. MADI™ (machinable austempered ductile iron) overcomes this difficultly and provides the highly desirable combination of high strength, excellent low temperature toughness, good machinability and attractive finished component cost. The Machine Tool Systems Research Laboratory at the University of Illinois at Urbana-Champaign performed extensive machinability testing and determined the appropriate tools, speeds and feeds for milling and drilling (https://netfiles.uiuc.edu/malkewcz/www/MADI.htm). This paper provides the information necessary for the efficient and economical machining of MADI™ and provides comparative machinability data for common grades of ductile iron (EN-GJS-400-18, 400-15, 450-10, 500-7, 600-3 & 700-2) for comparison.

The US Army uses a light tactical High-Mobility Multi-Purpose Wheeled Vehicle (HMMWV) which, due to the amount of armor added, requires air conditioning to keep its occupants comfortable. The current system uses R134a in a dual evaporator, remote-mounted condenser, engine-driven compressor system. This vehicle has been adapted to use an environmentally friendly refrigerant (carbon dioxide) to provide performance, efficiency, comfort and logistical benefits to the Army. The unusual thermal heat management issues and the fact that the vehicle is required to operate under extreme ambient conditions have made the project extremely challenging. This paper is a continuation of work presented at the SAE Alternate Refrigerants Symposium held in Phoenix last June [1].