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An Investigation into Jet Engine Inlet Flow Characteristics for Turbine-Powered Helicopters

Reilly, Daniel
http://rave.ohiolink.edu/etdc/view?acc_num=osu1429608968

Abstract Details

2015, Master of Science, Ohio State University, Aeronautical and Astronautical Engineering.
Many modern military helicopters, such as the CH-47 Chinook and the CH-53 Stallion class, have side mounted powerplant/turboshaft engines that ingest the freestream air to generate power. These engines operate under the same aerodynamic and thermodynamic principles as an ordinary gas turbine engine. However, these turboshafts do not produce any thrust of their own but rather they are used to power the helicopter’s lifting and propulsion systems. A turboshaft’s performance is largely based on the pressure distribution at the face of the compressor. Pressure distortion can lead to high dynamic loading on the rotor and stator blades as well as contributing to the possibility of stall and surge due to the pressure differences. As the helicopter’s rotor “chops” through the air, pressure differences are created by the moving blades which are then ingested by the engine’s inlet, situated below the rotor. The study conducted was aimed at determining the inlet distortions based on a variety of parameters including, but not limited to: advance ratio, cross winds and rotor/engine locations. The analysis was conducted at The Ohio State University’s Aerospace Research Center’s Jet Engine Test Simulation facility. A scale model of the rotor was constructed and integrated with an engine simulator. An engine simulator is a iii scaled version of an engine that accurately models scaled version of full-scale flow conditions. The engine simulator used in this study has no internally moving parts but instead uses high pressure air to simulate the flow. The rotor model consisted of a 3-horsepower electric motor that drove 20 inch long blades at desired rotational speeds. The simulator inlet was equipped with four pressure rakes each with three total pressure probes at equal area radial locations. The engine simulator cowling inlet had the ability to be rotated 45 degrees, leading to a total of 24 total pressure measurements. In addition to the experimental model created, a computational fluid dynamics simulation was run to gain as much detail on the inlet pressure and the streamlines generated by the setup. The computational study was conducted using the commercial package Fluent through the computing labs at Scott Laboratory. An initial study was run with just the engine simulator to verify the package, then an actuator disk model was included that simulates the downwash from the rotor blades. Actuator disk theory is the simplification of a rotor to a short cylinder with a pressure difference across the boundaries to create a certain velocity. With the aid of computational visualization a double duct was designed to reduce the inlet distortion by reducing the curvature of the streamlines entering the engine. Both of these setups have contributed to the understanding of the effects that these rotors have on their own turboshaft engines. The results from these tests will aid in understanding how the flow field within the engine changes with varying outside parameters for the potential of improving the performance of the engine. This iv improvement in engine performance will therefore improve the helicopters’ performance by requiring less fuel and power will be needed to provide torque to the rotor shaft.
Clifford Whitfield (Advisor)
Richard Freuler (Committee Member)
101 p.
Aerospace Engineering; Engineering

Recommended Citations

Citations

  • Reilly, D. (2015). An Investigation into Jet Engine Inlet Flow Characteristics for Turbine-Powered Helicopters [Master's thesis, Ohio State University]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=osu1429608968

    APA Style (7th edition)

  • Reilly, Daniel. An Investigation into Jet Engine Inlet Flow Characteristics for Turbine-Powered Helicopters. 2015. Ohio State University, Master's thesis. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=osu1429608968.

    MLA Style (8th edition)

  • Reilly, Daniel. "An Investigation into Jet Engine Inlet Flow Characteristics for Turbine-Powered Helicopters." Master's thesis, Ohio State University, 2015. http://rave.ohiolink.edu/etdc/view?acc_num=osu1429608968

    Chicago Manual of Style (17th edition)

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