Highly Aggressive Inter Compressor Duct With Active Flow Control: Numerical Validation of Pulsed Jet Actuators With Unsteady Simulations

The application of active flow control (AFC) methods in an intercompressor duct (ICD) offers the possibility of further length reduction while suppressing separations. In particular, pulsed jet actuators (PJAs) are advantageous because the pulsation enhances mixing processes. However, the PJAs require fluid that has already been compressed by the downstream high-pressure compressor. Therefore, injecting this high-momentum fluid from a downstream component makes this approach very expensive. Consequently, a highly optimized design is required to achieve the maximum separation suppression while minimizing the external energy. However, the numerical optimization requires steady simulations to find an optimum design in manageable time scales. Therefore, this study helps in understanding if any aspects of unsteadiness are neglected by optimizing the PJA implementation with steady methods. Furthermore, the influence of the steady-state assumption in the optimization is quantified. The influence of the unsteadiness of the PJA is investigated by comparing steady and unsteady simulations. The unsteady simulations include unsteady Reynolds-averaged Navier–Stokes and delayed detached-eddy simulation. The numerical simulations are validated against experimental data obtained at the TU Berlin ICD test rig. After evaluating the different approaches, a conclusion is drawn on how unsteady flow control methods can be efficiently optimized. Consequently, the study shows that all the methods investigated have their advantages and disadvantages. Their use must be carefully selected according to the objective of the investigation.