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A Modeling System to Understand the Design and Performance of a Two Spool Gas Turbine Engine

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The purpose of my Honors Thesis was to generate a tool that could be implemented by Aerospace students at Arizona State University. This tool was created using MatLab which is

The purpose of my Honors Thesis was to generate a tool that could be implemented by Aerospace students at Arizona State University. This tool was created using MatLab which is the current program students are using. The modeling system that was generated goes step-by-step through the flow of a two spool gas turbine engine. The code was then compared to an ideal case engine with predictable values. It was found to have less than a 3 percent error for these parameters, which included optimal net work produced, optimal overall pressure ratio, and maximum pressure ratio. The modeling system was then run through a parametric analysis. In the first case, the bypass ratio was set to 0 and the freestream Mach number was set to 0. The second case was with a bypass ratio of 0 and fresstream Mach number of 0.85. The third case was with a bypass ratio of 5 and freestream Mach number of 0. The fourth case was with a bypass ratio of 5 and fresstream Mach number of 0.85. Each of these cases was run at various overall pressure ratios and maximum Temperatures of 1500 K, 1600 K and 1700 K. The results modeled the behavior that was expected. As the freestream Mach number was increased, the thrust decreased and the thrust specific fuel consumption increased, corresponding to an increase in total pressure at the combustor inlet. It was also found that the thrust was increased and the thrust specific fuel consumption decreased as the bypass ratio was increased. These results also make sense as there is less airflow passing through the engine core. Finally the engine was compared to two real engines. Both of which are General Electric G6 series engines. For the 80C2A3 engine, the percent difference between thrust and thrust specific fuel consumption was less than five percent. For the 50B, the thrust was below a two percent difference, but the thrust specific fuel consumption clearly provided inaccurate results. This could be caused by the lack of inputs provided by General Electric. The amount of fuel injected is largely dependent on the maximum temperature which is not available to the public. Overall, the code produces comparable results to real engines and can display how isolating and modifying a certain parameter effects engine performance.

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Date Created
  • 2015-05

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Performance and scaling analysis of a hypocycloid wiseman engine

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The slider-crank mechanism is popularly used in internal combustion engines to convert the reciprocating motion of the piston into a rotary motion. This research discusses an alternate mechanism proposed by

The slider-crank mechanism is popularly used in internal combustion engines to convert the reciprocating motion of the piston into a rotary motion. This research discusses an alternate mechanism proposed by the Wiseman Technology Inc. which involves replacing the crankshaft with a hypocycloid gear assembly. The unique hypocycloid gear arrangement allows the piston and the connecting rod to move in a straight line, creating a perfect sinusoidal motion. To analyze the performance advantages of the Wiseman mechanism, engine simulation software was used. The Wiseman engine with the hypocycloid piston motion was modeled in the software and the engine's simulated output results were compared to those with a conventional engine of the same size. The software was also used to analyze the multi-fuel capabilities of the Wiseman engine using a contra piston. The engine's performance was studied while operating on diesel, ethanol and gasoline fuel. Further, a scaling analysis on the future Wiseman engine prototypes was carried out to understand how the performance of the engine is affected by increasing the output power and cylinder displacement. It was found that the existing Wiseman engine produced about 7% less power at peak speeds compared to the slider-crank engine of the same size. It also produced lower torque and was about 6% less fuel efficient than the slider-crank engine. These results were concurrent with the dynamometer tests performed in the past. The 4 stroke diesel variant of the same Wiseman engine performed better than the 2 stroke gasoline version as well as the slider-crank engine in all aspects. The Wiseman engine using contra piston showed poor fuel efficiency while operating on E85 fuel. But it produced higher torque and about 1.4% more power than while running on gasoline. While analyzing the effects of the engine size on the Wiseman prototypes, it was found that the engines performed better in terms of power, torque, fuel efficiency and cylinder BMEP as their displacements increased. The 30 horsepower (HP) prototype, while operating on E85, produced the most optimum results in all aspects and the diesel variant of the same engine proved to be the most fuel efficient.

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Date Created
  • 2014