Skip to Main Content
 

Global Search Box

 
 
 
 

ETD Abstract Container

Abstract Header

Large-scale structures and noise generation in high-speed jets

Hileman, James Isaac

Abstract Details

2004, Doctor of Philosophy, Ohio State University, Mechanical Engineering.
This work examines the relationship between the dynamics of large-scale turbulence structures and the acoustic far-field of high Reynolds number, high-speed jets. Three Mach numbers were examined: 0.9, 1.3 and 2.0. The Mach 1.3 jet was also modified with delta tabs. A novel microphone array / algorithm was developed, tested and then used to locate sources of individual sound waves in space and time. Noise source distributions were compared to and correlated with flow visualization images that were examined with Proper Orthogonal Decomposition (POD). Time and frequency-domain analyses showed the acoustics of Mach 0.9 and 1.3 jets differed from the Mach 2.0 jet due to Mach wave emission in the latter case. Differences associated with turbulence structure scale were observed within the acoustic measurements. The addition of delta tabs led to streamwise vorticity production and the regulation and augmentation of spanwise vorticity. These modifications led to an upstream shift in the noise production regions of the jet and a shift away from the delta tab location. The regions of noise generation coincided with the location where the sides of the mixing layer merge (Mach 0.9, 1.3, 2.0, single-tab, quad-tab jets) or were dramatically altered (bifurcating region of the dual-tab jet). The streamwise vortices were not a strong, direct acoustic source for frequencies on the order of the peak jet radiation at the angle of maximum sound emission. The Mach 1.3 jet was analyzed for periods of noise generation (NG) and relative quiet (RQ) using simultaneously acquired flow and noise source localization data. POD modes were used to reconstruct cross-stream images and a series of crudely phase-locked streamwise images for the two cases. Both image planes showed the lower order POD modes that possess larger scale structures are important to the RQ while the higher order modes with relatively smaller scales dominate the NG. Within the phase-locked NG streamwise images, a series of robust structures form approximately one convective time scale before noise emission and then rapidly disintegrate as fluid is entrained to the jet’s core. The observed NG process bares many similarities to the breakdown of an instability wave.
Mo Samimy (Advisor)
394 p.

Recommended Citations

Citations

  • Hileman, J. I. (2004). Large-scale structures and noise generation in high-speed jets [Doctoral dissertation, Ohio State University]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=osu1078776079

    APA Style (7th edition)

  • Hileman, James. Large-scale structures and noise generation in high-speed jets. 2004. Ohio State University, Doctoral dissertation. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=osu1078776079.

    MLA Style (8th edition)

  • Hileman, James. "Large-scale structures and noise generation in high-speed jets." Doctoral dissertation, Ohio State University, 2004. http://rave.ohiolink.edu/etdc/view?acc_num=osu1078776079

    Chicago Manual of Style (17th edition)