A rapid equivalent modeling and simulation method for the flow field of the grille at the entrance of submerged inlet based on wall effect and local loss

Abstract

While the grille at the entrance of the inlet enhances stealth performance, it also has a significant impact on the internal flow characteristics. Due to the huge difference between the grille parameters and the overall aircraft size, the simulation cost of the inlet’s internal flow characteristics increases sharply. To address this, this paper decomposes the influence of the grille on the inlet flow field into two aspects: wall effects and local losses. In order to retain the wall effects of the grille on the airflow as much as possible, the wall thickness of the grille is eliminated, and a virtual body force model is constructed based on local losses to characterize the physical properties of the local flow field, establishing an equivalent method for the grille of submerged inlets. Taking a typical submerged inlet configuration with a grille as an example, the efficiency and accuracy of the conventional simulation method and the fast equivalent method proposed in this paper are compared. The results show that the equivalent method proposed in this paper can significantly improve the numerical simulation efficiency while accurately capturing the influence of the grille on the airflow of the submerged inlet, and it exhibits good applicability under different working conditions and geometric configurations. Compared with the results of traditional body-fitted grid calculations, the relative errors in total pressure recovery coefficient and circumferential total pressure distortion at the outlet under cruise conditions are 0.1% and 10.5%, respectively; for different working conditions and geometric configurations, the relative errors in total pressure recovery coefficient are approximately 3%, and the relative errors in circumferential total pressure distortion are approximately 10%. In addition, this equivalent method can not only obtain the performance parameters and total pressure distribution of the inlet but also the distribution laws of other physical parameters, such as Mach number distribution and swirl angle distribution. Therefore, this equivalent method has high engineering practical value.