6.4 Algorithm of Spatial Aerodynamic Optimization of the Blade Cascades of Axial Turbines

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The proposed method of optimization of the cascades is based on the joint usage of the formal macromodeling and LPτ search and includes the following steps [37]:

The plan of computing experiment is created [1, 2]. In the given range of variable parameters, defining a stacking line, the points, in which computations will be carried out, are determined.

The blades matching of the plan points parameters are constructed and computation domain and grids are generated.

Values of objective function for each combination of parameters are determined. For this purpose CFD computation and post-processing of results are carried out.

Coefficients of a full square-law polynomial type (1.2) or (1.12) of objective function and restriction function in the set range of varied parameters are determined. Using LPτ search the minimum of value losses in the cascade

6.4

is determined, under condition that the mass flow through it satisfies the condition

6.5

The scope of varied parameters has been changed:

  • – а) if the minimum of the objective function appears on the border of the range of variation parameters, the last is displaced aside of this boundary;
  • – b) if the minimum of the objective function are inside of the range, but macromodel is not sufficiently precise, the range decreases;
  • – c) if the minimum function falls within the range and macro-model is accurate enough, checking CFD-calculation is carried out and if its results with sufficient accuracy coincide with optimization results on macromodel, optimization is completed, otherwise the range decreases. Repeat pt. 1 – 4.

 

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