Flow Control of a Cascade Thrust Reverser

The present experimental investigation explores utilization of active flow control for mitigation of the flow separation over a shortened turning section of a cascade thrust reverser, also known as a bullnose. Such a reduction in the nominal thrust reverser length, with minimal or no penalty in increased drag and reduced reversed thrust, would reduce both the wetted area and weight of the nacelle. To minimize the performance penalty, the shortened thrust reverser sector model is equipped with an array of small-scale fluidic oscillating jets that are used as the flow control elements for the oncoming Mach numbers of M≈0.24–0.53. The flow control effectiveness is demonstrated over four bullnose geometries, down to 47% of the nominal bullnose length. The established scaling laws indicate that the mass flow rate recovery is directly proportional to the actuation flow rate for a given flow configuration and condition, and it is strongly nonlinear with the flow pressure ratio for a given flow control rate. Furthermore, it is shown that, in terms of the dimensionless flow control parameter Cq, low- and high-curvature bullnose geometries exhibit different trends in the thrust reverser mass flow rate recovery.