Separation Control and the Energy Expenditure Using Pulsed Co-Flow Jet

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This paper numerically studies the control effectiveness and energy expenditure of pulsed Co-Flow Jet (PCFJ) applied on the widely used NASA hump. The 2D unsteady Reynolds averaged Navier-Stokes equations are solved for the simulations. An unsteady velocity boundary condition is developed for the in-house FASIP (Flow-Acoustics-Structure Interaction Package) CFD solver to simulate the pulsed CFJ. The pulsed jet simulation is validated with the NASA tested case actuated by a synthetic jet for the NASA hump flows. The predicted synthetic jet results are in good agreement with the experiment in terms of pressure coefficient distributions. For the pulsed CFJ, a novel actuation model with continuous suction and pulsed injection is proposed to mimic the zero-net-mass-flux pulsing process and calculate the power consumption. The pulsed CFJ and steady CFJ (SCFJ) are compared for their control effectiveness and power consumption at their minimum momentum coefficient to fully attach the flow. The pulsed CFJ is simulated with two reduced frequencies (F+) of 0.74 and 1.67. All the cases have identical CFJ injection and suction slot locations and sizes. Results show that the steady and pulsed CFJ cases have the similar control effectiveness as their pressure coefficient distributions are virtually overlapped. The PCFJ requires about 28% lower mass flow rate than that of the SCFJ. However, the PCFJ requires substantially higher power consumption due to significantly increased total pressure loss for pulsed jet actuation.