| Hybrid rocket engine is a propulsion system where fuel and oxidant are stored in different physical state.Due to the typical diffusion combustion in the chamber,one of the shortages of hybrid rocket engine is the low regression rate.Paraffin,a liquefying fuel with low melting point and low viscosity,is applied to solve the problem fundamentally.The combustion model of paraffin is established and the process of combustion and flow in paraffin fuel rocket motor is investigated by numerical means.The numerical results are compared with the experiment results to verify the accuracy and reliability of the calculation model.The combustion of paraffin goes through two physical processes of melting and vaporization,and the melted paraffin forms a film instability affected by the shear of main flow,which greatly improves the regression rate of fuel.The effect of oxidant flow rate,wedge angle of fuel slab,and metal particle on the combustion of paraffin are numerically simulated.The oxidant flow rate influences the regression rate by influencing the position of the combustion zone.The increase of flow rate will compress the combustion area of paraffin fuel to the its surface,increasing both the regression rate the combustion efficiency of paraffin fuel.The wedge angle of paraffin slab affects the instability of the melting layer covered on the paraffin surface to change the regression rate.As the angle decreases,a more obvious instability of melting layer and entrainment of liquid droplets is formed so that the regression rate increases.The addition of metal additives increases the energy characteristic of fuel,leading to a higher combustion temperature and a higher regression rate to a certain extent.The combustion characteristics of paraffin under the condition of the combustion chamber are further investigated and the influence of injection position of oxidant on the combustion is simulated.The regression rate of paraffin is the highest when the oxidant is injected uniformly.After adding the metal particles,the energy of paraffin fuel is increased,the combustion temperature is higher,and the regression rate of paraffin is improved.The combustion characteristics and factors that affects the combustion of paraffin are studied by numerical means,and the relevant laws are obtained,which can be the references for the design of practical paraffin-based hybrid rocket engines. |
