Control of the unsteady flow in a stator blade row interacting with upstream moving wakes
January 1993
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| Format: | Technical Report |
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Cambridge, Mass. : Gas Turbine Laboratory, Massachusetts Institute of Technology, [1993]
2016
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| Online Access: | http://hdl.handle.net/1721.1/104752 |
| _version_ | 1826215238636142592 |
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| author | Valkov, Theodore V. (Theodore Valkov) |
| author2 | Massachusetts Institute of Technology. Gas Turbine Laboratory |
| author_facet | Massachusetts Institute of Technology. Gas Turbine Laboratory Valkov, Theodore V. (Theodore Valkov) |
| author_sort | Valkov, Theodore V. (Theodore Valkov) |
| collection | MIT |
| description | January 1993 |
| first_indexed | 2024-09-23T16:19:47Z |
| format | Technical Report |
| id | mit-1721.1/104752 |
| institution | Massachusetts Institute of Technology |
| last_indexed | 2024-09-23T16:19:47Z |
| publishDate | 2016 |
| publisher | Cambridge, Mass. : Gas Turbine Laboratory, Massachusetts Institute of Technology, [1993] |
| record_format | dspace |
| spelling | mit-1721.1/1047522019-04-10T12:33:33Z Control of the unsteady flow in a stator blade row interacting with upstream moving wakes Valkov, Theodore V. (Theodore Valkov) Massachusetts Institute of Technology. Gas Turbine Laboratory TJ778.M41 G24 no.215 Compressors -- Blades Unsteady flow (Fluid dynamics) January 1993 Includes bibliographical references (pages 63-66) A computational study of the unsteady flow in a 2-D stator blade row interacting with upstream rotor wakes has been carried out. A direct spectral-element Navier-Stokes solver has been used for the laminar flow regime (Re<10,000). Turbulent calculations (Re>106 are based on the Baldwin-Lomax turbulence model. The rotor wakes are represented by velocity distortions moving along the inlet boundary of the computational domain. After interception, the rotor wake migrates towards the pressure surface of the stator blades where it forms a pair of counter-rotating vortices. A moving series of such vortex pairs is the dominant form of unsteady flow over the pressure surface. The unsteady flow over the suction surface is characterized by a street of co-rotating vortices, produced in the leading edge region. These vortices consist of boundary layer fluid distorted and detached by the passing wakes. Downstream of the leading edge, each of these vortices induces an associated, opposite-sign vortex. The blade loading fluctuations arising from wake interaction, are of two kinds. First, a strong pressure pulse occurs on the leading edge upon wake interception. This pulse is a potential flow effect associated with the excess tangential velocity in the wake. Second, a moving pattern of pressure fluctuations, associated with the vortices, is present over the blade surface. The pressure fluctuations are negative on the suction surface, and positive on the pressure surface. The unsteady flow features over the suction surface can be adequately represented by linearized perturbation calculations, where the disturbance flow associated with the wakes is linearized about a steady viscous flow. Three parameters influence the unsteady flow over the suction surface-stator blade loading, excess wake momentum in the stator frame, and wake reduced frequency. The strength of the disturbance flow vortices is directly proportional to the wake momentum and decreases at higher reduced frequencies. An adverse pressure gradient results in stronger vortices and pressure fluctuations. On the pressure surface, the amount of unsteady flow depends on the excess wake momentum only. Strategies for controlling the unsteady flow are simulated using appropriate blade surface boundary conditions. Fluid removal from the suction surface prevents formation of vortices and reduces the associated loading disturbances. Fluid injection from the pressure surface reduces the pressure fluctuations there. Supported by the Applied Research Laboratory at Pennsylvania State University 2016-10-06T21:22:25Z 2016-10-06T21:22:25Z 1993 Technical Report http://hdl.handle.net/1721.1/104752 28449884 GTL report #215 xiv, 180 pages application/pdf Cambridge, Mass. : Gas Turbine Laboratory, Massachusetts Institute of Technology, [1993] |
| spellingShingle | TJ778.M41 G24 no.215 Compressors -- Blades Unsteady flow (Fluid dynamics) Valkov, Theodore V. (Theodore Valkov) Control of the unsteady flow in a stator blade row interacting with upstream moving wakes |
| title | Control of the unsteady flow in a stator blade row interacting with upstream moving wakes |
| title_full | Control of the unsteady flow in a stator blade row interacting with upstream moving wakes |
| title_fullStr | Control of the unsteady flow in a stator blade row interacting with upstream moving wakes |
| title_full_unstemmed | Control of the unsteady flow in a stator blade row interacting with upstream moving wakes |
| title_short | Control of the unsteady flow in a stator blade row interacting with upstream moving wakes |
| title_sort | control of the unsteady flow in a stator blade row interacting with upstream moving wakes |
| topic | TJ778.M41 G24 no.215 Compressors -- Blades Unsteady flow (Fluid dynamics) |
| url | http://hdl.handle.net/1721.1/104752 |
| work_keys_str_mv | AT valkovtheodorevtheodorevalkov controloftheunsteadyflowinastatorbladerowinteractingwithupstreammovingwakes |