Skip to Main Content
 

Global Search Box

 
 
 
 

Files

File List


ucin1085666850.pdf (31.76 MB)

ETD Abstract Container

Abstract Header

AN INVESTIGATION OF INNOVATIVE TECHNOLOGIES FOR REDUCTION OF JET NOISE IN MEDIUM AND HIGH BYPASS RATIO TURBOFAN ENGINES

CALLENDER, WILLIAM BRYAN
http://rave.ohiolink.edu/etdc/view?acc_num=ucin1085666850

Abstract Details

2004, PhD, University of Cincinnati, Engineering : Aerospace Engineering.
This research project has developed a new, large-scale, nozzle acoustic test rig capable of simulating the exhaust flows of separate flow exhaust systems in medium and high bypass turbofan engines. This rig has subsequently been used to advance the understanding of two state-of-the-art jet noise reduction technologies. The first technology investigated is an emerging jet noise reduction technology known as chevron nozzles. The fundamental goal of this investigation was to advance the understanding of the fundamental physical mechanisms responsible for the acoustic benefits provided by these nozzles. Additionally, this study sought to establish the relationship between these physical mechanisms and the chevron geometric parameters. A comprehensive set of data was collected, including far-field and near-field acoustic data as well as flow field measurements. In addition to illustrating the ability of the chevron nozzles to provide acoustic benefits in important aircraft certification metrics such as effective perceived noise level (EPNL), this investigation successfully identified two of the fundamental physical mechanisms responsible for this reduction. The flow field measurements showed the chevron to redistribute energy between the core and fan streams to effectively reduce low frequency noise by reducing the length of the jet potential core. However, this redistribution of energy produced increases in turbulent kinetic energy of up to 45% leading to a degradation of the chevron benefit at higher frequencies. Trends observed with respect to the chevron geometry showed that the chevron penetration could be matched to the exhaust flow conditions to optimally balance the trade between low frequency reduction and high frequency increase to maximize reductions in EPNL. Secondly, a completely new technology, known as fluidic injection, was investigated. This technology consists of applying continuous air injection, from a number of small injection jets, at the nozzle exit plane to reduce jet noise. The principal advantage of such an approach is that it is an active technology that can be activated as needed and, as such, may be more acceptable in aircraft engines from a performance standpoint than passive technologies. This study successfully demonstrated the feasibility of this technology by showing that effective jet noise reduction can be provided in a broad range of flow conditions using less than 1% of the mean jet mass flow. An investigation of injection geometric parameters identified the injection pitch angle as the most influential parameter with respect to jet noise reduction. Furthermore, an investigation of scaling effects showed a momentum ratio of approximately 1.5% to provide reductions in sound pressure level between 1 and 2 dB across a wide range of frequencies for a wide range of flow conditions and scales including both single stream and dual stream flows. PIV flow field measurements identified the fundamental physical mechanism of the noise reduction to be a near uniform reduction in shear layer turbulence.
Dr. Ephraim Gutmark (Advisor)
334 p.
Aeroacoustics; Jet Noise; Separate Flow Exhaust Systems; Separate Flow Exhaust Nozzles; Chevron Nozzles; Chevrons; Fluidic Injection; Fluidics

Recommended Citations

Citations

  • CALLENDER, W. B. (2004). AN INVESTIGATION OF INNOVATIVE TECHNOLOGIES FOR REDUCTION OF JET NOISE IN MEDIUM AND HIGH BYPASS RATIO TURBOFAN ENGINES [Doctoral dissertation, University of Cincinnati]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1085666850

    APA Style (7th edition)

  • CALLENDER, WILLIAM. AN INVESTIGATION OF INNOVATIVE TECHNOLOGIES FOR REDUCTION OF JET NOISE IN MEDIUM AND HIGH BYPASS RATIO TURBOFAN ENGINES. 2004. University of Cincinnati, Doctoral dissertation. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=ucin1085666850.

    MLA Style (8th edition)

  • CALLENDER, WILLIAM. "AN INVESTIGATION OF INNOVATIVE TECHNOLOGIES FOR REDUCTION OF JET NOISE IN MEDIUM AND HIGH BYPASS RATIO TURBOFAN ENGINES." Doctoral dissertation, University of Cincinnati, 2004. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1085666850

    Chicago Manual of Style (17th edition)

ucin1085666850
1,152
© 2004, all rights reserved.
This open access ETD is published by University of Cincinnati and OhioLINK.