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Thermoacoustic heat engines convert heat into useful energy by generating acoustic waves from a heat source that can then be extracted as useful work. These engines are inexpensive, robust, versatile, and capable of extracting energy from a wide variety of heat sources ranging from waste heat from power plants to exhaust heat of vehicles. In this article, our investigation focuses on using simulation workflows to improve the performance of thermoacoustic engines. We begin with validating the workflows with published data for both traveling wave and standing wave thermoacoustic engines. Following that, we investigate the effect of changing the working fluid and the operating pressure to increase acoustic power. This study uses a coupled PowerFLOW™ and PowerTHERM™ methodology to simulate the buoyancy-driven flows that generate acoustic pressure waves. Good correlations were observed for both traveling and standing wave thermoacoustic engines.

For fuel cell vehicles, it is essential that the hydrogen tank be both compact and have sufficient hydrogen to ensure reasonable driving range for which there is a need to pressurize the hydrogen in the tank at levels much higher than that of atmospheric pressure. Furthermore, fast filling is an important consideration in order to minimize time to refuel hydrogen in the tank. In this article, we investigate a Computational Fluid Dynamics (CFD) methodology to see whether we can simulate the fast filling of the hydrogen tank. We performed simulations on an existing validation case using coupled simulation approach between the PowerFLOW® flow solver and PowerTHERM® the thermal solver. For an accurate simulation at elevated pressure levels, we implemented a real gas behavior that is more accurate than the ideal gas equation of state for under these conditions. We observe good agreement with experimental data for both bulk and local variations in temperature.

Selective Catalytic Reduction (SCR) is a process where one injects an aqueous solution of urea into a diesel exhaust system in order to reduce NOx emissions. The urea solution known as AdBlue® or Diesel Exhaust Fluid (DEF) is stored in a DEF Tank that can under cold weather conditions freeze over. Since AdBlue® is unusable while frozen, we use heaters installed in the tanks to melt AdBlue® with government regulations mandating time required to melt AdBlue® in the tank. In this article, we investigate whether a CFD (Computational Fluid Dynamics) based methodology can accurately evaluate time required in melting AdBlue® for a given DEF Tank and heater coil design for a production vehicle as per standard testing procedure. Simulations used a coupled methodology with PowerFLOW® as the flow solver and PowerTHERM® as the thermal solver. The flow simulation did require an accurate modelling of phase change from solid to liquid for AdBlue®.

It is particularly easy to get tunnel vision as a domain expert, and focus only on the improvements one could provide in their area of expertise. To make matters worse, many Original Equipment Manufacturers (OEMs) are silo-ed by domain of expertise, unconsciously promoting this single mindedness in design. Unfortunately, the successful and profitable development of a vehicle is dependent on the delicate balance of performance across many domains, involving multiple physics and departments. Taking for instance the design of a Heating, Ventilation & Air Conditioning (HVAC) system, the device’s primary function is to control the climate system in vehicle cabins, and more importantly to make sure that critical areas on the windshield can be defrosted in cold weather conditions within regulation time. With the advent of electric and autonomous vehicles, further importance is now also placed on the energy efficiency of the HVAC, and its noise.

Design and evaluation of construction equipments and vehicles in the construction industry constitute a very important but expensive and time consuming part of the engineering process on account of large number of variants of prototypes and low production volumes associated with each variant. In this article, we investigate an alternative approach to the hardware testing based design process by implementing a Computational Fluid Dynamics (CFD) simulation based methodology that has the potential to reduce the cost and time of the entire design process. The simulation results were compared with test data and good agreement was observed between test data and simulation.

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.

At the onset of soak, air and surface temperatures in an engine bay enclosure are elevated since temperature of heat sources are high while convective cooling is sharply reduced as a result of airflow being shut off from the inlet grilles of the vehicle leading to temperature spikes. Accurate simulation of this important thermal and flow regime that is natural convection driven, highly transient and complex is therefore very important. In this investigation, we simulate flow in the engine bay at the onset of soak with fixed thermal boundary conditions where the geometries representing the engine bay and components are simplified. Good agreement was observed with detailed experimental data available in references for both velocities and temperatures.

An important metric in the vehicle brake design process, the cool-down time for a brake disk, strongly influences the durability and reliability of brakes. However, the brake cool-down time is a function of many vehicle and chassis factors, making it time consuming and expensive to evaluate and optimize in hardware testing. In this study, we investigate an alternative approach to hardware testing for evaluating brake design cool-down time by implementing a CFD (Computational Fluid Dynamics) simulation based methodology. The simulation cases were all compared with test data and good agreement was observed between test data and simulation over a wide range of design parameters. It is therefore demonstrated that accurate simulation is a promising new approach to the brake design process.

Many critical thermal issues that occur in vehicles are uncovered only under more “thermally stressed” driving conditions that are transient in nature such as abruptly changing vehicle speed or turning off fan and engine. Therefore, for flow simulations to be useful in the vehicle design process, it is imperative that these simulations have the ability to accurately model long term transient thermal convection on full vehicles. Presented are simulations for a passenger vehicle driving at 60 kilometers per hour followed by a complete stop. The simulations were performed using a coupling between the flow and thermal solver and in the process, taking into account convection, conduction and radiation effects. Temperature predictions were made both under steady state conditions and during the key-off. Good agreement with the measurements was observed.

Accurate simulation of long term transient thermal convection is critical to automotive related thermal and fluid flow applications. For instance, long term thermal transients are relevant to “key-off” situations in which a moving vehicle brought to a stop leads to a usual initial spike in temperature followed by a drop as the heat sources are turned off. Presented are simulations of a simple tube and plate configuration that captures the contribution of all heat transfer effects and complexities of a vehicle key-off process. The simulations were performed using a coupling between the flow solver and the thermal simulation package that includes conduction and radiation effects. The simulation results were compared with the test data for steady state forced convection cases and transient natural convection cases. Good agreement was observed for both steady and transient simulations.