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The Importance of S-1 Stream Surface Twist in the Analysis of Inviscid Flow Through Swept Linear Turbine Cascades
Published January 01, 1987 by Institution of Mechanical Engineers in United Kingdom
Flow through the blading of a flared axial turbine is analogous to flow past an aircraft swept wing since, in each case, the aerofoil spanwise axes are non-orthogonal to the principal flow direction. In the present paper, swept cascade models are used to investigate the physical mechanisms by which sweep may induce both blade-to-blade and meridional flow disturbances in turbomachines, with particular attention being paid to the role of S-1 stream surface distortion. Quasi 3-D and fully 3-D computational methods are applied to the solution of inviscid flow through two test case swept cascade geometries, for flow regimes varying from virtually incompressible to high speed, subsonic. Blade-to-blade and meridional flow presentations of the computed solutions are given, and computed S-1 stream surfaces are shown. Finally, the fully 3-D flow solutions are interpreted systematically, in order to produce a general understanding of the individual disturbance mechanisms associated with sweep, and their complex interactions. Using this background, suggestions are made concerning the importance of S-1 surface twist effects in the analysis of flow through real turbine nozzle rows.