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Experimental investigation of an annular diffuser for axial flow fan configurations at different inflow profiles

Walter, Johannes; Wurz, Dieter; Hartig, Stefan; Gabi, Martin

Axial fans are used in power plants for fresh air supply and flue gas transport. A typical configuration consists of an axial fan and annular diffuser which connects the fan to the following piping. In order to achieve a high efficiency of the con-figuration not only the components have to be optimized but also their interac-tion. The present study focuses on the diffuser of the configuration. Experiments are performed on a diffuser-piping configuration in order to investigate the influ-ence of the velocity profile of the fan outlet on the pressure recovery of the con-figuration. Two different diffuser inlet profiles are generated, a homogeneous profile and a profile with the typical outlet characteristics of a fan. The latter is generated by the superposition of screens in the inlet zone. The tests are conduct-ed at a high Reynolds number (Re≈4∙10^5). Mean velocity profiles and wall shear stresses are measured with hydraulic methods (Prandtl and Preston tubes). The results show that there is a lack of momentum at the outer wall of the diffuser and high shear stresses at the inner wall in case of the homogeneous inflow pro-file. For the typical fan outlet profile it can be shown that there is an opposite ef-fect with high wall shear stresses at the outer wall while the boundary layer of the inner wall lacks momentum. ... mehr

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DOI: 10.5445/IR/1000066757
Cover der Publikation
Zugehörige Institution(en) am KIT Fachgebiet Strömungsmaschinen (FSM)
Publikationstyp Zeitschriftenaufsatz
Publikationsjahr 2016
Sprache Englisch
Identifikator ISSN: 0354-9836, 2334-7163
KITopen-ID: 1000066757
Erschienen in Thermal science
Heft 00
Seiten 183
Schlagwörter annular diffuser, flow separation, fan outflow profile, Preston method, pressure recovery
Nachgewiesen in Dimensions
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