A multi-stage coupling adaptive method for thermochemical nonequilibrium gas

Abstract

A multi-stage coupling adaptive simulation method for thermochemical nonequilibrium gas is introduced. Based on the mathematic ideal of Lambert's local integration method, the method decomposes the time integration process of the thermochemical nonequilibrium steady flow simulation into multiple ladder-type advancing stages from simple to complex, and applies the progressive approximation strategy of gradually coupling characteristic equations of thermochemical effects to achieve the rapid flowfield simulation. Second, numerical comparative analysis are conducted on the arc-jet wind tunnel test flow conditions of the hemisphere model with radius of R = 50.8 mm. Finally, numerical evaluation of the aerothermal characteristics is carried out for the typical flow state of the OV102-like space shuttle model. The numerical studies show that the new method has excellent effect of accelerating the convergence. Compared with the commonly used uniform advancing implicit method of the tight coupling of flow/thermochemical reactions, the computational efficiency is improved by about 1/3 in the one-temperature 5-species chemical model, and nearly 1 time in the two-temperature 11-species thermochemical model. In addition, the method shows good computational reliability and numerical stability, and can satisfy the requirement of the simulation of the hypersonic flows over complex topological configurations under the large CFL number condition.