The sonic boom generated by aircraft flying at a supersonic speed is one of the primary problems of the development of supersonic commercial aircraft. Sonic boom prediction tools have been developed based on the weak shock theory, and even complex phenomena are evaluated as simplified models. Hence, because of their limited applications, some complex phenomena such as sonic boom cutoff arising from shock wave diffraction has been difficult to analyze. For improving the state of the art, we focus on Computational Fluid Dynamics (CFD) analysis over the entire flow field, ranging from the near field around a supersonic aircraft to the far field extending to the ground.
The challenge
Direct simulation for sonic boom enables us to precisely evaluate sonic boom intensity in various flight and atmospheric conditions, including complex phenomena such as sonic boom cutoff.
The accurate prediction of sonic boom is difficult due to the multi-scale nature of the phenomenon: The scale varies from millimeter around an aircraft to kilometer in a real stratified atmosphere. In addition, sonic boom intensity significantly changes according to the flight pattern such as acceleration and manuever, and atmospheric variability such as atmospheric turbulence and wind. The main challenges are to realize direct simulation for sonic boom generated from a three-dimensional aircraft configuration and to investigate complex phenomena such as sonic boom cutoff.
The research
Direct simulation for sonic boom propagation through a real atmosphere has been recently performed using the boundary fitted coordinate (BFC) grid. However, the application of the simulation using the BFC grid is limited, and thus the simulation method needs to be further developed for considering a three-dimensional aircraft configuration. In this research, the simulation method using the adaptive mesh refinement (AMR) method under consideration of a stratified atmosphere has been developed to analyze sonic boom generated from a real aircraft configuration.
Publications
- Rei Yamashita and Kojiro Suzuki, Full-Field Simulation for Sonic Boom Cutoff Phenomena, Transactions of the Japan Society for Aeronautical and Space Sciences, Vol.58, No.6, 2015, pp. 327-336: http://dx.doi.org/10.2322/tjsass.58.327
- Rei Yamashita and Kojiro Suzuki, Full-Field Sonic Boom Simulation in Stratified Atmosphere, AIAA Journal, Vol.54, No. 10, 2016, pp. 3223-3231: http://dx.doi.org/10.2514/1.J054581
- R. Yamashita, L. Wutschitz and N. Nikiforakis (2019). A three-dimensional model for modelling sonic boom in a stratified atmosphere. (in preparation).