Numerical analysis of effects of laser energy on supersonic cavity flow with help of reduced order modelling

High speed flows over open cavities can produce complex unsteady flow fields that are important practical concern in aerospace applications. These complex unsteady flow fields include both the small-scale pressure fluctuations typical of turbulent shear flows and a significant resonance, the frequency and amplitude of which depend on the cavity geometry and external properties. In this study, to decrease these pressure oscillations in the flow region, laser energy deposition method, which is an active flow control method, is applied numerically. The impacts of parameters as amount, frequency and location of laser energy are also examined. To understand the effects of laser energy, the sound pressure levels (SPL) observed in cavity region are compared to each other. As a result of laser energy deposition, several changes are observed in the pressure values and the oscillation mechanism in the flow. Proper Orthogonal Decompositon (POD) method is applied to the results of computational fluid dynamics (CFD) simulations of the cases with controlled and uncontrolled cavity flow. The POD modes which include the spatial information and the modes amplitudes that include the temporal information of the large and dominant structures in the flow are specified. By using these parameters, reduced order models for the systems are obtained. To obtain correct and efficient cavity flow measurement for control purposes is an important process. Sensors can only be placed on the cavity surfaces for real time flow control. Optimum sensor locations are determined by application of POD to pressure values which are obtained from cavity surfaces. The Proper Orthogonal Decomposition method is applied to the supersonic cavities with different length to depth (L/D) ratios of 1, 3, 5.07, 7.6, and 10. The results are explicated and compared with each other. The effects of L/D ratio on cavity flow mechanism are also presented.