Book Description

Completed research is reported for an dynamic numerical investigation of unsteady flow in supersonic and hypersonic aircraft inlets. An explicit dynamic solution adaptive mesh computational code was further developed and used to obtain dynamic solutions for an axisymmetric mixed compression inlet and a generic dual mode scramjet inlet isolator diffuser combination. To improve robustness, an existing implicit code was modified for time accuracy and the solution adaptive mesh algorithm was installed. The inlet unstart phenomenon was simulated through perturbation of freestream and downstream conditions (axisymmetric inlet) and through downstream throttling for the dual mode 3-D configuration. Axisymmetric unstart could be induced by a 10% freestream temperature increase or a 5% backpressure increase. Comparison of the results with experiment, where available, indicate that stability margins assessed through inviscid design or quasi-steady experiment may need revision when dynamics are considered. Conclusions are drawn concerning specifics of the flow phenomena and directions for future research are suggested. Lack of highly resolved dynamic experimental data is a pacing item and will prevent full verification of future work.