NUMERICAL STUDY OF SHEAR-INDUCED HEATING IN HIGH-SPEED NOZZLE-FLOW OFLIQUID MONOPROPELLANT

A numerical study is performed which focuses on peak temperatures expe rienced by a liquid monopropellant during high-speed injection in a sm all-diameter nozzle. Attention is focused on short-duration injection during which the nozzle wall boundary layer is predominantly laminar. An unsteady ID analysis of the temperature distribution associated wit h sudden fluid acceleration over a fiat insulated boundary is I first conducted. Expressions are provided which relate the normalized peak w all temperature to the prevailing Eckert and Prandtl numbers. Results reveal a quadratic dependence of the normalized wall temperature on im pulse velocity, and a nonlinear variation with Prandtl number. Next, s imulation of high-speed flow in an axisymmetric nozzle is performed. T he numerical schemes are based on finite-difference discretization of a vorticity-based formulation of the mass, momentum, and energy conser vation equations. Implementation of the numerical schemes to flow Of L P 1846 in a 4 mm diameter nozzle indicates that preignition is likely to occur for velocities higher than 200 m/s. The effects of wall hear transfer and temperature-dependent properties are also discussed.