Cycle analysis for fuel-inducted internal combustion engine configurations

A quasi-one-dimensional computer code based on a fuel-air cycle analysis wa s developed to predict the performance of two- and four-stroke fuel-inducte d engines. The analysis was developed to provide boundary conditions for a finite element analysis to predict thermal and mechanical loading of carbon -carbon pistons for use in advanced internal combustion engine concepts. Th e computer code can predict the required boundary conditions, which are gas pressure and temperature and heat transfer coefficients as a function of c rank angle, along with engine indicated and brake power output, thermal eff iciency and mean effective pressure, The code utilizes a variable specific heat calculation throughout the cycle. The compression of an air-fuel-resid ual gas mixture is calculated followed by a finite rate burn, where the bur n duration is calculated on the basis of the turbulent flame speed and cyli nder geometry. The residual gas content is calculated by an iterative techn ique. During combustion and expansion, ten equilibrium combustion product c onstituents are tracked. Engine friction, instantaneous heat transfer and b lowby past the rings are calculated on the basis of empirical correlations. The tendency for engine knock or autoignition of the fuel is also calculat ed. Good agreement is obtained when compared with actual engine operation f or power output, thermal efficiency and exhaust gas temperature.