Numerical Simulation of Reacting flow and Fuel Regression Rate in N2O/HTPB Hybrid Rocket Motor

Paper number

IAC-09.C4.P.6

Author

Mr. Fanli Shan, Tsinghua University, China

Coauthor

Dr. Lingyun Hou, China

Coauthor

Dr. Vadim Zakirov, Tsinghua University, China

Coauthor

Prof. Hai-yun Zhang, Tsinghua University, China

Coauthor

Dr. Junfeng Li, China

Year

2009

Abstract

Hybrid rocket motors have several advantages for propulsion applications. These motors can be restarted and throttled, are less expensive and safer than solid rocket motors. Modern hybrid rocket motor designs also have drawbacks such as oxidizer-to-fuel ratio shifting during operation and lower combustion efficiencies compared to solid rocket motors and liquid rocket engines. Scaling of hybrid rocket motor design is not a straight-forward task due to possible combustion instabilities.
Many efforts have been made to address above difficulties. Several problems in calculating the combination of fuel regression rate and reacting flow both in the combustion chamber and the nozzle still remain. The suggested numerical program for simulation of N2O/HTPB hybrid rocket motor operation has been developed to assist solutions. In this program the system of unsteady Navier-Stokes equations supplemented with k-$\varepsilon$ turbulent model is solved for two-dimensional axisymmetric flow geometry case along with detailed chemical composition mechanisms for N2O decomposition and turbulent combustion in reacting flow from the injector to the nozzle covering start-up transient and steady state. A compressible SIMPLE algorithm is applied for the equations’ solution. A HTPB pyrolysis model as well as the coupling based on mass and energy conservations at gaseous-solid interface is employed for calculation of fuel regression rate and solid-phase temperature distribution. The moving interface is automatically adjusted by the grid. A correction method is suggested to determine modified flow field as fuel regresses.
The program calculates distribution of flow velocities, pressure, density, temperature, and chemical species as functions of time inside the hybrid rocket motor. The fuel regression rate and time-dependent chamber pressure as well as motor thrust are compared to experimental data for the program validation. According to the simulation, new coefficients for fuel regression rate equation with an axial term have been derived for N2O/HTPB propellant combination. The numerical results indicate improvements to the existing design of N2O/HTPB hybrid rocket motor.

Abstract document

IAC-09.C4.P.6.pdf

Manuscript document

IAC-09.C4.P.6.pdf (🔒 authorized access only).

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