Turbprop or turbojet engines are the main means of providing motivepower for flight. Any improvements which can be made to thesetechnologies in terms of power or fuel efficiency are significantand important developments. After first setting the scene with a short account of aeroenginedevelopment, the book goes on to show how a super-turbochargedaeroengine can be significantly more efficient. A detailed accountof the studies into the new design philosophy is given and thenumerical results of the computational model of this engine designmodel are analysed. The unusual design of these piston engine unitsis theoretically modelled and their mechanical design is discussedin some detail.
Conventional jet engine perfomance
Performance at altitude
Axial piston engine
Turbine and high-speed alternator design
Numerical modelling and results
Compound turbocharged engine
Introduction to a new engine type: an overview; a historical viewpoint; by way of comparison - optimizing conventional aeroengine performance; themes on the alternative - the compound-assisted engine; the comparison of various engine types' specific power outputs; summary. Further considerations: overview; an analysis of flow stability; the rotordynamic type supercharger; the permissible turbine entry temperature; the high-speed electrical transmission; emissions considerations; modelling fluid properties; the detonation limit revisited; control of engine power output; summary. Mechanical engine design: a new approach; the axial piston engine and the turbocharger; a new valve design; summary. Optimization: Why is multi-dimensional optimization necessary? a mathematical technique for optimization; applying the method; a comment on adaptive optimization; summary. Numerical modelling of the new engine type: overview; comments upon a quasi-steady approach; the full time-marching model; aspects of gas flow modelling; further details of the time-marching technique; summary. numerical results: validation of the optimization scheme; validation of the engine model; some notes on the optimization methodology; optimization results at sea level; optimization results at 11km altitude; a brief comparison with the poppet-valved engine at high bore-to-stroke ratios; thermal efficiency as a function of pressure ratio; approximate calculation of power-to-weight ratios at sea-level; comparison of simple calculations with time-marching calculations; summary. Conclusions: conclusions arising from the computational results; constraints upon specific power output; some further thoughts; a future project? the rotary engine. Appendices: the polytrophic efficiency; the calculation of gas turbines efficiency assuming constant fluid properties; the thermal efficiency of the Otto cycle; the approximate calculation of burnt fuel/air mixture composition and other parameters; the gradient vector of a quadratic function; the use of mutually conjugate directions; derivation of the conjugate-gradient algorithm; the entropy function.