New Large-Scale Model Inlet Performance Testing Capability for the AEDC PWT 16T/S Wind Tunnels

摘要

Based on the recommended practice for wind tunnel propulsion integration testing, inlet model scale should be greater than 10% (Ref. 1). However, application of this minimum recommendation does not leave much room for auxiliary flows controlled by individual flow plugs or for scaling bleed/bypass systems that may be more sensitive to Reynolds number effects. Therefore a 15% or larger scale model is desirable. Over time as turbine engine face diameters have increased, the scale of wind tunnel models has been decreasing because of a desire to use an existing Aerodynamic Interface Plane (AIP) rake, resulting in models near or at the minimum recommended scale. Other than smaller model scale, a secondary concern is the increased application of highly-offset inlet flow paths in aircraft design. Highly-offset flow paths can cause increased flow angularity (generally caused by swirl) at the engine airframe AIP. Traditional style total pressure probes cannot accurately measure total pressure in a high flow angularity environment. As the use of highly-offset flow path systems that may generate flow angularity has increased, the desire to measure the swirl angle (the angle of the flow entering the AIP) has become of interest. Currently, most wind tunnel test programs employ a separate AIP with swirl probes to obtain the flow angularity data, requiring a significant model hardware change and repeating the test matrix. These reasons (scale, old probe design, multiple AIPs) and the average age of the available engine mass flow systems (MFS) have driven AEDC to invest 1.6 million dollars into two new engine mass flow systems. Details of the requirements process for the engine mass flow systems, the design and CFD data (including a CFD calibration), and the results and conclusion are contained herein.