Some Attempts to Bridge the Gap Between DNS and Wind Tunnel Testing of Hypersonic Boundary Layer Transition

Abstract

In recent years, DNSs have been used to study boundary layer turbulence transitions. However, these DNSs leave a large uncertainty in the way the initial disturbance is given, and there is a large gap with the initial disturbance in actual flights and wind tunnel tests. This paper presents two examples of DNSs for turbulent transition processes in hypersonic wind tunnels that aim to bridge the gap between DNSs and wind tunnel tests by making the initial disturbances as close to reality as possible. In the DNS simulating a hypersonic wind tunnel nozzle, a turbulent boundary layer was captured on the nozzle wall to simulate the freestream disturbances by the acoustic noise radiated from the turbulent boundary layer. In the DNS for two flat plates placed opposite each other to simulate a wind tunnel test, the noise radiated by the turbulent boundary layer on one flat plate successfully caused the turbulent transition of boundary layer on the other flat plate.