PAST RESEARCH
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Computational Fluid Dynamics of Automotive Refueling Systems
Working with partners at Honda R&D, we are developing CFD models capable of predicting the complex multi-phase fluid dynamics required to design low hydrocarbon vapor emitting/high-performance automotive refueling systems. Model development is coupled with experimental validation to ensure that the simulations can accurately capture the flow through the nozzle and the output spray leading to the turbulent flow through the filler pipe and the phase change and hydrocarbon vapor flow within the fuel tank and the onboard refueling vapor recovery system (ORVR).
Related Publications:
- Development and Validation of a CFD Simulation to Model Transient Flow Behavior in Automotive Refueling Systems
- Considerations for CFD Simulations of a Refueling Pump Nozzle with Application to the Computer Aided Engineering of a Vehicle Refueling System
- Experimental investigation of automotive refueling system flow and emissions dynamics to support CFD development
- Computer aided engineering of an automobile gasoline refueling system
Computational Fluid Dynamics of a JP-8 Fueled Unmanned Aerial Vehicle
The US military is beginning to recognize the benefits of a Single-Fuel Policy, as several studies have been conducted to analyze the feasibility. Heavy Hydrocarbon fuels are of interest to the military as a prime candidate for the single fuel policy. However, since JP-8 is less volatile and has short ignition delays, it is more prone to cause engine knock during combustion. Stratified combustion is being used to reduce the probability of engine knock by promoting conventional combustion propagation from the point of ignition (spark plug) down to the piston. Stratified combustion is achievable by modifying the fuel injector properties to change the injection rate shape. Rate Shape is a plot of mass over time of the fuel as it comes into the cylinder of the engine. Due to the unique characteristics of JP-8, extensive research must be conducted to find the best parameters for proper ignition in gasoline engines through the manipulation of fuel injection.
Fuel Volatility and Distillation Dependent Property Measurement
The volatility or phase change behavior of fuels is being measured using the Advanced Distillation Curve (ADC) apparatus (top right) and method developed at NIST.1 The distillation curve is a highly important fuel property to determine engine compatibility and is an important metric to derive simple fuel surrogates. The ADC method provides true thermodynamic state points which allow for equation of state modeling and has a unique sampling feature which when coupled with appropriate chemical analyses (e.g. GC-MS/FID and Windom_CV_2017) can provide the composition of the distillate fractions, allowing for evaluation of relevant fuel properties as the fluid evaporates (including e.g., HOV and Hcomb).
Counter-flow Flame Studies – Effect of Endothermic Reactions in Regenerative Cooling Applications
Work is being carried out to measure flame properties of real fuels using a counter-flow flame burner. The counter-flow flame provides an excellent platform to study the combustion behaviors of fuels as it can be estimated as one dimensional (along the z-axis) such that the physics can be modeled and compared to the experiment. This provides a tool to validate kinetic mechanism and transport properties of fuels. By coupling a high pressure reactor to the counter-flow flame burner, the affect of endothermic reactions on the subsequent combustion of jet fuels is being investigated. In particular diffusion flame extinction strain rates between the un-reacted fuel and the thermally stressed fuel are being measured and compared to show how the regenerative cooling process can alter flame dynamics/stability.
Fuel Evaporation – Impact on Combustion and Particulate Matter Emissions
Using distillation curve measurements as the basis, a fuel droplet evaporation model of multi-component petroleum/biofuel blended fuels has been developed to show the impact of high heat of vaporization and non-ideal (azeotropic) interactions, which are characteristic of biofuels, on fuel droplet life times and composition. Recently, trends predicted by the model have been used to explain elevated PM emissions observed by colleagues at NREL’s ReFuel Lab for high ethanol concentrated gasoline fuels in direct injection spark ignition engine (DISI). Please find our recent paper for more information.