Abstract: Based on the needs of the rocket skid ground test， the researcher design the short-track rocket sled power system with large load and high acceleration， and it is conducted the theoretical and experimental influence study of ground effect on the flow field of the rocket motor tail nozzle. The 3-D numerical simulation of the rocket motor tail nozzle outer flow field was conducted for different conditions using FLUENT calculation software. It analyzed the influence of ground effect on the flow field characteristics of the motor tail nozzle when a single rocket and two rockets are working. For the short-track rocket sled power system with large load and high acceleration studied in this paper， both the influence of ground effect and the interaction between the two nozzles which appeared at 1.5ms， was more obvious at 2~3ms， and decreased at 5~20ms， finally， a stable tail flow field is formed. For rocket sled power system， the nozzle outlet diameter is 275mm， the distance between the axis and the ground is not less than 472mm， and the distance between the axis of double nozzles is not less than 680mm. After the rocket sled move for 20ms， the effect of the ground and the interaction between the double rocket motors become very small.

Key words: Rocket sled test;Rocket motor;3-D numerical simulation;Nozzle flow field;Ground effect of flow field

摘要： 基于火箭撬地面试验的需要，设计了大载荷高加速的短轨火箭橇动力系统，并对地面效应对火箭发动机尾喷管流场的影响进行了理论和试验研究。文中采用FLUENT计算软件对不同条件下的火箭发动机尾喷管外流场进行了三维数值仿真，分析了单枚火箭以及双枚火箭工作时，地面效应对发动机尾喷管流场特性的影响。本文研究的大载荷高加速的短轨火箭撬动力系统，地面效应的影响和双尾喷管之间的相互作用都是在1.5ms时开始显现，在2~3ms时比较明显，在5~20ms开始减小，最后形成稳定的尾部流场。对于喷管出口直径275mm、轴线距离地面不小于472mm和双喷管轴线距离不小于680mm的火箭橇动力系统，在火箭橇运动起来20ms之后，地面效应影响和双火箭发动机之间相互作用变得非常小。

关键词: 火箭橇试验;火箭发动机;三维数值仿真;喷管流场;流场地面效应