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A Literature Review of Low Pressure Steam Turbine Exhaust Hood and Diffuser Studies

Burton, Zoe; Ingram, Grant; Hogg, Simon


Zoe Burton


This paper summarizes the findings from research studies carried out over the last 30 years, to better understand the flows in steam turbine low pressure exhaust hoods and diffusers. The work aims to highlight the areas where further study is still required. A detailed description of the flow structure is outlined and the influence of the last turbine stage and the hood geometry on loss coefficient is explored. At present, the key challenge faced is numerically modeling the three-dimensional, unsteady, transonic, wet steam exhaust hood flow given the impractically high computational power requirement. Multiple calculation simplifications to reduce the computational demand have been successfully verified with experimental data, but at present there is no ‘best-practice’ approach to reduce the computational time for routine design exercises. This paper highlights the importance of coupling the exhaust hood to the last stage steam turbine blades to capture the interaction; ensuring the total pressure and swirl angle profiles, along with the tip leakage jet are accurately applied to the diffuser inlet. The nonaxial symmetry of the exhaust hood means it is also important to model the full blade annulus. More studies have emerged modeling the wet steam and unsteady flow effects, but more work is required in this area to fully understand the impact on the flow structure.


Burton, Z., Ingram, G., & Hogg, S. (2013). A Literature Review of Low Pressure Steam Turbine Exhaust Hood and Diffuser Studies. Journal of Engineering for Gas Turbines and Power, 135(6), Article 062001.

Journal Article Type Article
Publication Date May 1, 2013
Deposit Date Aug 6, 2013
Journal Journal of Engineering for Gas Turbines and Power
Print ISSN 0742-4795
Electronic ISSN 1528-8919
Publisher American Society of Mechanical Engineers
Peer Reviewed Peer Reviewed
Volume 135
Issue 6
Article Number 062001
Keywords Pressure, Flow (Dynamics), Diffusers, Exhaust systems, Turbines, Geometry, Steam turbines, Blades, Separation (Technology).