Dynamic ScreenVanes for the Generation of User-Prescribed, Time-Varying Inlet Distortion

Next generation air platforms commonly incorporate embedded propulsion systems that require compact offset diffuser that can produce AIP flow that varies strongly in both space and time. This subjects the first stage rotor to significant variations in loading and incidence angles that adversely affecting engine operability and high-cycle fatigue in ways that are not currently fully understood. As a result, the ability to test engines and fans under representative conditions is needed. Means of reproducing steady state total pressure inlet flow distortion patterns for engine and compressor rig testing have been around since the 1950’s (Rannie, 1957). More recently, researchers at Virginia Tech have developed StreamVanesTM (Hoopes, 2013) for generating swirl distortion and ScreenVanesTM (Fohnapfel, 2020) for generating a combined swirl and total pressure distortion in-flow condition. Each of these technologies have been used extensively over the years for testing both commercial and military engines. The objective of the proposed Phase II effort is to develop concepts for the next generation of distortion generating devices, Dynamic Stream/ScreenVanes that will look to add an unsteady component to the swirl and pressure distortion patterns created by current Stream/ScreenVaneTM technology. Similar to their steady-state predecessors, Dynamic Stream/ScreenVanes will use a set of vanes and screens to generate the desired, mean total pressure and swirl distortion. In order to add the unsteady components of distortion, both active and passive control methods will be used. The active methods in the proposed work use jets of air that can be actuated as desired to provide the desired unsteadiness. The passive methods superimpose the unsteadiness produced by the vortical shedding of bluff bodies onto the steady distortion pattern created by a traditional StreamVane to produce the desired mean and time-varying distortion pattern.