CHEMICAL KINETICS AND ROCKET NOZZLE DESIGN

摘要

The effect of chemical kinetics on rocket nozzle design was investigated for the particular case of hydrogen gas flowing adiabatically through a typical rocket nozzle having a chamber-to-throat-area ratio of 2 to 1. For comparative purposes the following types of flow were considered: (a) constant composition (frozen equilibrium), (b) instantaneous chemical equilibrium (shifting equilibrium), and (c) kinetic chemical equilibrium. A stepwise iteration process was employed to perform the integration of the differential equation in case (c). In each case the gas entered the nozzle at a temperature of 3500K and a pressure of 20 atm and was allowed to expand isentropically to an exhaust pressure of 1 atm. The results for a mass flow rate of 1000 gm/sec are presented. The instantaneous equilibrium flow assumption not only gives a higher specific impulse, but also requires a larger nozzle than either the kinetic or the constant composition flow assumption. The kinetic equilibrium flow resluts are intermediate between those for instantaneous equilibrium flow and those for constant composition flow, the relative position depending on the magnitude of the reaction rate which governs the kinetic equilibrium. (Author)