Two-Dimensional Thermodynamic and Flow Analysis of the Simple Hot-Air Engine

Abstract

Attention focuses on the annular gap between displacer and cylinder shell as the gas passes between expansion and compression spaces. Equations are formulated for velocity and temperature distributions as a function of time and the distance coordinate directions—radial and axial. Local, instantaneous entropy creation rates due to viscous dissipation and heat transfer are computed without the need to refer to the usual friction factor and coefficient of convective heat transfer. From considerations of exergy an estimate of indicated thermodynamic work per cycle follows. This is expressed in terms of performance maps covering the entire range of possible speeds, charge pressures and sizes for a machine of given geometry.