Effects of Heat Transfer in Divergent Section of Laval Nozzle on Exhaust Velocity and Area Ratio

Abstract

The effects of heating or cooling of the supersonic flow in a Laval nozzle have been investigated numerically. We focus on the exhaust velocity and the area ratio at given expansion ratios, which are ranged from 30 to 16,000. This range is equivalent to the area ratio from 4 to 400 at the specific heat ratio of 1.3 under isentropic expansion. Two types of heat profile are considered: pulsed heat transfer (PHT) and distributed heat transfer (DHT). The relations of Rayleigh flow and isentropic expansion are used for PHT. The exhaust velocity is higher than the isentropic value for the case where heat is provided near the throat. In other cases, the exhaust velocity is less than the isentropic value. The equivalent point of heat transfer is introduced for DHT. Using this equivalent point, the results for DHT exhibit the same trend as the results for PHT. This indicates that the effects of DHT can be predicted directly from results for PHT without numerical analyses.