Including Fuel Effects in 1-D Automotive Powertrain Simulations

Many automotive engine designers are familiar with the 1-D powertrain simulation capabilities of Gamma Technologies’ GT-SUITE. This is a common workhorse for system exploration and optimization of overall engine performance and efficiency. In GT-SUITE a network of component models is used to test the impacts of changes to the turbocharger, manifold configuration, exhaust-gas recirculation (EGR) loop, engine cylinder or aftertreatment devices on the overall powertrain performance and controllability. Engine cylinder-to-cylinder and cycle-to-cycle effects can also be studied to assess engine performance metrics.

Mutual ANSYS and Gamma Technologies customers can now evaluate fuel effects within GT-Power simulations, using ANSYS Chemkin-Pro. The interoperability of these two products gives engineers the ability to test the impact of different fuel compositions on engine performance.

1-D powertrain simulation capabilities of Gamma Technologies’ GT-SUITE

GT-SUITE User Interface with Chemkin-Pro selected as an “external” Engine Cylinder model

ANSYS’ Model Fuel Library provides the fuel chemistry models, which have been well validated over a broad range of engine conditions, representing natural gas, gasoline, diesel, biofuels and even jet fuels, as well as combinations thereof. Chemkin-Pro’s Reaction Workbench tools allow fuel models to be easily formulated to match specific real-world fuel properties. A Chemkin-Pro simulation takes just a few minutes, even with very detailed chemistry, so the exploration of fuel effects will not add significantly to the powertrain simulation time.

It’s no secret that the fuel affects engine behavior. Your car’s owner’s manual probably tells you what grade of fuel to use to get the best performance; usually this is about reducing knocking that can cause wear and tear.  And you might notice you get different gas mileage in the winter vs. summer, due to seasonal changes in the fuel blend. For engine and fuel designers, such effects are also critical to meeting aggressive industry goals that call for reduction in CO2 emissions and an increase in fuel efficiency. One of the main barriers to meeting those goals in today’s gasoline engines is a tradeoff between increasing efficiency and engine reliability, where the onset of engine knock has come to dictate practical limits to efficiency improvements. So engine researchers are looking for ways to push these limits, through the fuel formulation or other innovations. Putting better fuel kinetics into 1-D powertrain simulations allows fast exploration of these design options.

Here’s an example of how the stand-alone Chemkin-Pro Knock Model compares with experimental observation for different engine conditions using a detailed, multi-component fuel chemistry model. The coupling with GT-Power is expected to improve Chemkin results, especially for moderate EGR, where knocking may be borderline.

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Ellen Meeks

About Ellen Meeks

Director of Development, Reacting Flows at ANSYS. Ellen has led product development and engineering services for more than 15 years at Reaction Design, including oversight of all major software releases, industry consortia, and several government-funded research projects. Previously, she was a researcher at Sandia National Laboratories in the areas of combustion, materials, and plasma processing; she was one of the principal developers of the CHEMKIN Software.