LAGRANGIAN APPROACH TO AXISYMMETRIC SPRAY SIMULATION OF PINTLE INJECTOR FOR LIQUID ROCKET ENGINES

摘要

Movable pintle injectors are installed in bipropellant rocket engines to control the mass flow rate of the propellants and allow deep throttling with high combustion performance. A thin liquid sheet is formed by ejecting the liquid radially around the end of the pintle. This sheet is broken by axially injecting a gas propellant from an annular gap around the pintle nozzle. The device features a movable pintle rod, which allows the thickness of the liquid sheet to be changed. The volume of fluid modeling is used to estimate the varying thickness of the liquid sheet, which is equal to the pintle opening up to a critical point. A procedure with these results calculates the constants in a mathematical model of the liquid sheet breakup process. The comparison of breakup model constants with the pintle opening shows that the drop size constant B-0 has increased and the breakup time constant B-1 has decreased up to the critical point of the pintle opening due to an increase in the liquid mass flow rate, which is changed after the critical point of the pintle opening due to a slight decrease with the increase in the liquid mass flow rate. Axisymmetric spray simulation of the pintle injector, varying the drop size constant and breakup time constant in the breakup model, was performed using the Lagrangian approach. As a result, the comparison of the simulation result with the experimental data of the spray angle and Sauter mean diameter shows that the simulation results obtained via the calculated constants depend on the varying liquid sheet thickness and exhibited a good agreement.