THREE-DIMENSIONAL NUMERICAL SIMULATION OF THE FLOW FIELD IN HYBRID ROCKET MOTOR WITH WAGON-WHEEL FUEL GRAIN

摘要

This paper presents the three dimensional numerical simulations of hybrid rocket motor with wagon wheel grainand investigates the flow field distribution characteristics and motor performances. The numerical model isestablished based on the Navier-Stokes equations with turbulence, chemical combustions, fuel pyrolysis and solidgasboundary interactions. A two-step combustion model is selected for the gaseous phase combustions, and thesolid-gas interface boundary formulation is developed based on the energy conservation equation. The flow fieldsand motor performances are then presented and discussed based on the 98% hydrogen peroxide (HP) and hydroxylterminated polybutadiene (HTPB) propellant combination. The results show that the flow fields present apparentthree dimensional characteristics. The flame layer forms in the interface of the oxidizer flow and the fuel pyrolysisproducts, and the profile of it is similar with the fuel port. With the axial location increasing, the fuel regression ratedecreases sharply at first and then increases to a steady level. At a certain cross section, regression rates are higher inthe points near the flame layer for larger temperature gradients and convective heat fluxes. The performances of thecharacteristics velocity and vacuum specific impulse, which may be mainly affected by the fuel configurations andstructural features, are slightly affected by the oxidizer to fuel ratio working condition, and the efficiencies of thecharacteristic velocity and specific impulse reach minimum values near the optimal oxidizer to fuel ratio.