Comparison of Dynamic Mesh Methods for Fairing Separation Process of Near Space High Speed Aircraft

The fairing separation process is a complex problem coupling dynamics and fluid mechanics, involving the solution of the six-degree-of-freedom equations and the N-S equations. The unsteady calculation of the dynamic mesh methods is a key technique. The coupling process was simplified to the uniform rotation process for the two-dimensional near space high speed aircraft, using smoothing and remeshing method, overset method, sliding and laying method respectively, which are easy to implement in engineering. The simulation results of three dynamic mesh methods were compared and analyzed, and conclusions are as follows: the steady flow fields of the three methods are consistent when fairing is closed, and they can capture the typical characteristics of the unsteady fairing separation process and reach the correct start consequence. In the unsteady process, the disappearance speed of separation region of smoothing and remeshing method is slower than overset method and sliding and layering method; overset method has the best computational flexibility, sliding and laying method has the fastest calculation speed, and smoothing and remeshing method has the highest theoretical precision. Because the grid update of smoothing and remeshing method is easy to fail for complex models, and sliding and laying method can only deal with the problem of known motion path, 3D coupling problems suggest the overset method. In the three-dimensional design of the fairing, the overflow effect should be considered to reduce the large separation area in front of the fairing and to reduce the difficulties in the control and thermal protection of the aircraft. © 2020, Editorial Department of Journal of Propulsion Technology. All right reserved.