PARAMETERISING THE GEOMETRY OF CURVED DIFFUSERS AND EXPANSION VANES USING LOGARITHMIC SPIRALS

Alexander BARON von HOHENHAU

Abstract


Recent research has examined how expanding corners can help to reduce the size, and thereby the cost, of wind and water tunnels. Expanding corners can be constructed using curved diffusers or expansion vanes. This paper examines traditional ways of defining the shape of curved diffusers. It is argued that these methods have shortcomings, such as non-continuity in channel curvature or changing rates of expansion. An iterative algorithm is presented to overcome these issues by defining diffuser shapes using logarithmic spirals. This approach enables precise control over diffuser expansion angle, turning angle as well as curvature. Furthermore, it is shown how the geometry of a logarithmic diffuser can be adapted and integrated into an expansion vane cascade.


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References


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