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An Investigation of Acoustic Wave Propagation in Mach 2 Flow

Nieberding, Zachary J

Abstract Details

2014, MS, University of Cincinnati, Engineering and Applied Science: Aerospace Engineering.
Hypersonic technology is the next advancement to enter the aerospace community; it is defined as the study of flight at speeds Mach 5 and higher where intense aerodynamic heating is prevalent. Hypersonic flight is achieved through use of scramjet engines, which intake air and compress it by means of shock waves and geometry design. The airflow is then directed through an isolator where it is further compressed, it is then delivered to the combustor at supersonic speeds. The combusted airflow and fuel mixture is then accelerated through a nozzle to achieve the hypersonic speeds. Unfortunately, scramjet engines can experience a phenomenon known as an inlet unstart, where the combustor produces pressures large enough to force the incoming airflow out of the inlet of the engine, resulting in a loss of acceleration and power. There have been several government-funded programs that look to prove the concept of the scramjet engine and also tackle this inlet unstart issue. The research conducted in this thesis is a fundamental approach towards controlling the unstart problem: it looks at the basic concept of sending a signal upstream through the boundary layer of a supersonic flow and being able to detect a characterizeable signal. Since conditions within and near the combustor are very harsh, hardware is unable to be installed in that area, so this testing will determine if a signal can be sent and if so, how far upstream can the signal be detected. This experimental approach utilizes several acoustic and mass injection sources to be evaluated over three test series in a Mach 2 continuous flow wind tunnel that will determine the success of the objective. The test series vary in that the conditions of the flow and the test objectives change. The research shows that a characterizeable signal can be transmitted upstream roughly 12 inches through the subsonic boundary layer of a supersonic cross flow. It is also shown that the signal attenuates as the distance between the source and sensors increases. Individual studies including detection sensor and source comparison, material selection, transfer rates, and shadowgraph imagery are also investigated. The acoustic signal is affected by the boundary layer, which is impacted by the shock train and its location. With the capability to characterize an acoustic signal within a scramjet engine to detect the shock train location, any disturbance in the acoustic signals can be linked to shock train displacement that could lead to an inlet unstart. With these results in mind, it is possible that acoustic hardware can be designed to be implemented into the scramjet engine to detect an inlet unstart before it should happen.
Ephraim Gutmark, Ph.D. D.Sc. (Committee Chair)
Jeffrey M Donbar, Ph.D. (Committee Member)
Michael S. Brown, Ph.D. (Committee Member)
Paul Orkwis, Ph.D. (Committee Member)
125 p.

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Citations

  • Nieberding, Z. J. (2014). An Investigation of Acoustic Wave Propagation in Mach 2 Flow [Master's thesis, University of Cincinnati]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1406881591

    APA Style (7th edition)

  • Nieberding, Zachary. An Investigation of Acoustic Wave Propagation in Mach 2 Flow. 2014. University of Cincinnati, Master's thesis. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=ucin1406881591.

    MLA Style (8th edition)

  • Nieberding, Zachary. "An Investigation of Acoustic Wave Propagation in Mach 2 Flow." Master's thesis, University of Cincinnati, 2014. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1406881591

    Chicago Manual of Style (17th edition)