Study of Transition on a Flared Cone with Forced Direct Numerical Simulation
thesisposted on 10.09.2021, 14:44 by Andrew James ShuckAndrew James Shuck
High speed boundary layers are an important aspect of vehicle design. It is crucial to know whether the boundary layer is laminar, turbulent, or transitional. The heat transfer rate increases dramatically from laminar to turbulent flow, so it must be considered when designing a high speed vehicle. This thesis studied a flared cone geometry with forced direct numerical simulation. This geometry has experimental data collected from a Mach 6 quiet tunnel and previous computational data. A two stage computational procedure is carried out in order to efficiently model the boundary layer. The first stage involved finding a full cone solution and creating an inlet profile. This inlet profile is imposed on the inlet of a 10-degree sector of the flared cone. This is done to achieve the desired resolution while maintaining reasonable computational costs for the DNS. With this setup, the second stage continues with a high-order basic state computation using the inlet profile. After the higher order basic state is computed, random forcing is applied using traveling plane waves to promote transition and the results are analyzed. Linear stability and frequency analysis is conducted and the unstable frequencies match with expected results. Transition is achieved using the forcing and qualitatively matches previous experimental and computational data for the flared cone. Just as in the experiment and previous computations, regions of primary and secondary streaks are found and have similar heat transfer magnitudes. However, the location of these streaks is different and is likely due to the setup of the computation.