Enhanced inverse design code and development of design strategies for transonic compressor blading
Date of Award
Doctor of Philosophy (PhD)
Mechanical and Aerospace Engineering
Thong Q. Dang
Inverse design code, Transonic compressor blading, Turbo machinery, Compressors
Aerospace Engineering | Structures and Materials
An inverse method for turbomachinery blade design is presented along with the three-dimensional turbulent viscous compressible solver that is coupled to it. The inverse method generates the blade camber surface that corresponds to the specified pressure loading, blade thickness and stacking axis. The analysis solver is raised to the level of current 'state-of-the-art' CFD codes used in industry, and the inverse formulation is enhanced to provide better blade description, improved accuracy and expanded capability. The resulting code is then applied to aerodynamically shape a few transonic axial compressor blades, while general guidelines are established for proper loading specification to improve blading characteristics within this inverse method.
Improvements to the flow analysis include proper treatment of the viscous terms and inclusion of the Baldwin-Lomax turbulence model. A comparison study shows that these models are sufficient for design purposes when compared to a baseline CFD code.
The inverse model is improved by using normal thickness instead of tangential thickness and by representing the camber surface using Non-Uniform Rational B-Splines (NURBS). This restricts the blade shape and provides blade smoothness in the chordwise and spanwise directions. Another contribution to the method is the leading and trailing edge description using NURBS and the resulting hybrid inverse technique. With this, the edge shapes are maintained throughout the calculation, ensuring the design is done in the appropriate flow field, and the grid can now be clustered to levels not previously allowable. This also allows better accommodation of strong spanwise gradients which is demonstrated to a limited extent.
Finally, the first really successful attempt at 3D viscous inverse transonic blade design is accomplished in this work. Loading guidelines for axial compressor blading are established along with proper execution of this inverse code for such designs. For transonic/supersonic blades, it is discovered that the specification of the blade pressure loading distribution must allow for the presence of a 'weak' passage shock (i.e. non-smooth pressure loading). Blade design studies show the use of this strategy to improve efficiency, address some multistage matching issues and reduce the effect of the tip leakage flow.
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Medd, Adam Jon, "Enhanced inverse design code and development of design strategies for transonic compressor blading" (2002). Mechanical and Aerospace Engineering - Dissertations. Paper 21.