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AllensteinJacobT_Dissertation2020.pdf (25.52 MB)

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Abstract Header

An Investigation of Jet Engine Test Cell Exhaust Stack Aerodynamics and Performance through Scale Model Test Studies and Computational Fluid Dynamics Results

Allenstein, Jacob T.
http://rave.ohiolink.edu/etdc/view?acc_num=osu1586515794023938

Abstract Details

2020, Doctor of Philosophy, Ohio State University, Aero/Astro Engineering.
Turbojet and turbofan engines must be properly documented and investigated prior to installation onto an aircraft. There are requirements that mandate that these engine tests and performance results to be within a high degree of accuracy while in a repeatable and reliable test environment. The `true’ thrust force produced by a turbine engine is one that is tested outside under no wind conditions. Unfortunately, since the engine is outside, it may be subjected to rain, wind, snow, or additional outdoor conditions. So, one avenue that investigators employ is by testing these engines within a specialized test cell or facility. One such facility, is an L-shaped indoor testing facility for these large, high-bypass turbofan engines. However, within a testing facility, the engine does not draw only the air into the facility but also induces a second flow which is a consequence of the interaction between the engine exhaust and the cell environment and augmentor/diffuser tube. Understanding the physics and flow conditions of this facility would be beneficial to the research and testing community. Currently, due to the complex nature and physics surrounding the exhaust-end of these facilities there is little to no research provided. So unfortunately, current research neglects providing results for these exhaust-end components and how they influence the front cell or engine performance. Specifically, one area of concern with these facilities stems from the high velocity and high velocity distortion values prior to the silencer package before the engine exhaust is emitted into the atmosphere. This silencer package is to assist with reducing the noise produced by the engine but constructed with expensive materials. With these high velocities and distortions, these expensive silencer packages deteriorate quickly over time. By lowering the high velocity and distortion, the silencer packages can operate more efficiently by reducing both the noise produced and the maintenance required. The aim of this study is to inform the research community through scale model experimental testing and computational fluid dynamics of the performance, velocities, and velocity distortions exhibited at the exhaust stack of a scaled model testing facility. A 1/12th L-shaped, scale model testing facility for large, high-bypass engines was constructed and operated with a GE90-B4 ejector-powered simulator. The base- line case employed a 54.5 degree, half-angle blast basket cone and the experimental results showed that the maximum velocity was 46.1 m/s while the CFD predicted 50.4 m/s at a plane located before the silencer package. The velocity distortion along this plane was calculated to be 188.5 percent for the experiment and 182.6 percent for CFD. By varying the blast basket cone’s geometry, the velocity distortion and maximum velocity were shown to decrease in value as the cone becomes reduced in degrees (i.e. becomes sharper). Just by reducing the cone to semi-vertex angle of 25 degrees, CFD predicted that the maximum velocity in the exhaust stack would decrease from 50.4 m/s down to 40.2 m/s. Additionally, CFD predicted that the velocity distortion would also decrease from 182.6 percent down to 175.3 percent. Results from a scaled model study utilizing this 25 degree cone showed that the velocity increased slightly but the overall velocity distortion decreased by 10.9 per- cent and matched the predicted CFD result within approximately 1.3 percent. An additional benefit from the experimental setup was the ability to obtain transient data. From this result it was seen through tuft visualization and the data that the 25 degree cone was able to reduce the localized velocity distortion for areas of high velocities (above 39 m/s). The 25 degree cone was able to successfully drive down the distortion to an average of 52.9 percent, where as distortion produced by the 55 degree cone was around 68.3 percent in these localized regions of maximum velocities above 39 m/s.
Randall Mathison (Advisor)
Richard Freuler (Advisor)
Clifford Whitfield (Committee Member)
152 p.
Aerospace Engineering
Turbofan Engine Testing Facilities; Ejector Powered Engine Simulators; Applied Aerodynamics

Recommended Citations

Citations

  • Allenstein, J. T. (2020). An Investigation of Jet Engine Test Cell Exhaust Stack Aerodynamics and Performance through Scale Model Test Studies and Computational Fluid Dynamics Results [Doctoral dissertation, Ohio State University]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=osu1586515794023938

    APA Style (7th edition)

  • Allenstein, Jacob. An Investigation of Jet Engine Test Cell Exhaust Stack Aerodynamics and Performance through Scale Model Test Studies and Computational Fluid Dynamics Results. 2020. Ohio State University, Doctoral dissertation. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=osu1586515794023938.

    MLA Style (8th edition)

  • Allenstein, Jacob. "An Investigation of Jet Engine Test Cell Exhaust Stack Aerodynamics and Performance through Scale Model Test Studies and Computational Fluid Dynamics Results." Doctoral dissertation, Ohio State University, 2020. http://rave.ohiolink.edu/etdc/view?acc_num=osu1586515794023938

    Chicago Manual of Style (17th edition)

osu1586515794023938
362
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This open access ETD is published by The Ohio State University and OhioLINK.