Flow separation control for robust conical diffuser design
Abstract/Contents
- Abstract
- In many practical applications of conical diffusers, the flow is fed by an annular flow passage formed by a center body. The annular inlet causes two possible regions of flow separation in the diffuser. The first is the separated wake of the center body and the second occurs if the boundary layer on the diffuser outer wall separates due to the adverse pressure gradient. The diffuser flow is further complicated by the strong coupling between the core flow and the outer wall boundary layer. The goal of this work was to optimize diffuser performance by controlling both separation regions. Magnetic resonance velocimetry was used to acquire three-dimensional three-component mean velocity measurements for an extensive array of diffuser configurations. The results show that a large separation bubble existed in the wake of the center body in the absence of flow control. Passive geometric perturbations were found to be ineffective in controlling the central separation bubble. An axisymmetric Coanda jet was shown to eliminate the bubble at a relatively low jet flow rate. The boundary layer separated asymmetrically when the Coanda jet was too strong. This mandates simultaneous control of both separation regions. A wavy-edge step-wall diffuser design was used to stabilize the outer wall boundary layer separation by fixing its location and allowing the separation bubbles to close quickly. The combination of Coanda blowing and the wavy-edge step-wall diffuser produced an outflow that was free of any flow separation. This configuration improved flow uniformity, increased pressure recovery, reduced loss, and reduced flow unsteadiness.
Description
| Type of resource | text |
|---|---|
| Form | electronic; electronic resource; remote |
| Extent | 1 online resource. |
| Publication date | 2012 |
| Issuance | monographic |
| Language | English |
Creators/Contributors
| Associated with | Lo, Kin Pong |
|---|---|
| Associated with | Stanford University, Department of Mechanical Engineering |
| Primary advisor | Eaton, John K |
| Thesis advisor | Eaton, John K |
| Thesis advisor | Elkins, Christopher J |
| Thesis advisor | Iaccarino, Gianluca |
| Advisor | Elkins, Christopher J |
| Advisor | Iaccarino, Gianluca |
Subjects
| Genre | Theses |
|---|
Bibliographic information
| Statement of responsibility | Kin Pong Lo. |
|---|---|
| Note | Submitted to the Department of Mechanical Engineering. |
| Thesis | Thesis (Ph.D.)--Stanford University, 2012. |
| Location | electronic resource |
Access conditions
- Copyright
- © 2012 by Kin Pong Lo
- License
- This work is licensed under a Creative Commons Attribution Non Commercial 3.0 Unported license (CC BY-NC).
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