A laminar wall jet undergoing transition is investigated using Particle Image Velocimetry (PIV) technique. The plane wall jet is issued from a rectangular channel with a parabolic velocity profile at the exit. The Reynolds number, based on the exit mean velocity and the nozzle width is 1450. To understand the global flow field, laser sheet/smoke flow visualizations are made along stream wise, spanwise, and cross-stream directions. To correlate the instantaneous vorticity distribution with the surface pressure fluctuations, surface pressure measurements are made. Under the present experimental conditions, it is found that the transition process is similar for both unforced and forced cases. Due to the necessity to obtain both temporal and spatial information of the flow field, a forced wall jet is considered for an extensive investigation. The instantaneous velocity and vorticity fields are measured by phase locking the flow field. These measurements provided the basis to understand the mechanisms involved in the formation of the initial vortex in the inner region of the wall jet and the subsequent interactions between the free shear layer (outer region) and the boundary layer (inner region) vortices. Results show that, under the influence of the shear layer vortex, the local boundary layer separates, becomes inviscidly unstable, and forms a vortex in the inner region. Once this inner region vortex is formed, both the free shear layer vortex and the boundary layer vortex form a couple and convect downstream. The mutual interactions between these inner and outer region vortices dominate the transition process. Further downstream, the emergence of the three dimensional structure in the shear layer initiates the complete breakdown of the flow. / Source: Dissertation Abstracts International, Volume: 54-11, Section: B, page: 5897. / Major Professor: Chiang Shih. / Thesis (Ph.D.)--The Florida State University, 1993.
| Identifer | oai:union.ndltd.org:fsu.edu/oai:fsu.digital.flvc.org:fsu_77044 |
| Contributors | Gogineni, Sivaram Prasad., Florida State University |
| Source Sets | Florida State University |
| Language | English |
| Detected Language | English |
| Type | Text |
| Format | 174 p. |
| Rights | On campus use only. |
| Relation | Dissertation Abstracts International |
Page generated in 0.0018 seconds