YOUNG-KEE MIN, Marquette University


In a hypergolic internal combustion engine, with a given amount of fuel per power stroke, we wish to optimize the output work and the efficiency by controlling fuel injection. We assume the engine is ideal except for friction losses which are given as a function of the cylinder pressure. The optimization is determined through calculations of thermodynamic efficiency, cylinder pressure versus crank angle and friction loss characteristics. A mathematical model is developed, and since the efficiency consists of output work over input fuel constraint, a calculus of variations approach will be used for solving the problem. The constraint however is not constant but variable. A new approach shows, among the value of constraint, that the maximum efficiency can be optimized. Its inverse problem, in which the output work is constraint, also can be optimized. The results of optimizing the problem, show that the fuel injection starting angle is approximately 5(DEGREES) after top dead center regardless of the amount of fuel injection per cycle, while the ending angle varies from approximately 8(DEGREES) to 20(DEGREES) with increasing fuel injection per cycle. In a hypergolic combustion engine, since the fuel is activated, the delayed combustion is not expected. It is easy to show that the Otto cycle is optimal, only when a frictionless engine is available, but this is not practical. The results show that the Hoppie cycle is up to 10% better in comparison to the Otto cycle with friction.

Recommended Citation

MIN, YOUNG-KEE, "OPTIMAL HYPERGOLIC COMBUSTION IN AN INTERNAL COMBUSTION ENGINE" (1986). Dissertations (1962 - 2010) Access via Proquest Digital Dissertations. AAI8708730.