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Using the AI-Powered SmartDO for Calculating the Design Limit of A Centrifugal Compressor


Using the AI-Powered SmartDO for Calculating the Design Limit of A Centrifugal Compressor

The design of compressor blades is a highly complex engineering problem. It has many constraints to meet, yet must simultaneously optimize numerous performance indicators. SmartDO's direct optimization solver, given a well-defined problem, can provide a more systematic and stable mathematical approach to analyze the limits under different design conditions.

When a centrifugal compressor is in operation, it not only requires high efficiency at the design point but also needs to consider the working range of stall flow and choke flow to adapt to varying operating conditions. Therefore, in the optimization design of a centrifugal compressor, it is necessary to ensure the efficiency, pressure, and flow at the design point, as well as to take stall conditions and choke into consideration.

This article presents an optimization case study of a single centrifugal compressor with practical engineering design requirements. The optimization objectives and constraints need to be defined in conjunction with practical design parameters. Different aerodynamic design condition parameters must be determined based on experience.

Figure 1 shows the geometric shape of the blades of the centrifugal compressor. The user wants to explore whether it is possible for raise the design point compression ratio to 1.9 and still satisfying the requirements at the design point, surge point, and choke point. The user has been unable to break through the design limitations using various design adjustment methods. Therefore, the user has turned to SmartDO for help, hoping to calculate whether a feasible design solution exists under the new design condition.

The formulation of the design problem in SmartDO is defined as followed. Among them, the 18 design variables are commonly used blade geometry parameters.

  • Find : DV1~DV18
  • Maximize : 0.7*Eff(DP)+0.3*Eff(SP)
  • Subjected to :
    • Shaft_Power(DP) <220KW
    • Pressure_Ratio(TT)>1.9
    • Massflow(CP) >3.5kg/s
  • DP: Design Point
  • SP: Surge Point
  • CP: Choke Point
  • TT: Total Pressure

Figure 1. Figure 1. The Geometric Shape of the Centrifugal Compressor Blades.

Using SmartDO, the direct numerical solution for this problem was calculated. SmartDO runed external CAE software a total of 289 times with its iteration curve shown in Figure 2 (left). It can be seen that SmartDO converged successfully.
Figure 2 (right) shows the sensitivity of all design variables for this design problem, considering effect of all objectives, constraints, allowable variation ranges, etc.

Figure 2 (Left) Nonlinear Solution Itertaion Convergence Curve of SmartDO.
Figure 2 (Right) The Sensitivity of All Design Variables Considering Effect of All Objectives, Constraints, Allowable Variation Ranges, etc.

Figure 3 (left) shows the initial design and the results after optimization with SmartDO. Figure 3 (right) shows the changes in blade shape. After optimized by SmartDO, the compression ratio has reached 1.9, and all other constraints meet the requirements.
Figure 4 shows a comparison of the performance curves of this centrifugal compressor before and after optimization with SmartDO. It can be seen that the compression ratio has significantly improved, and the efficiency has also notably increased in the crucial operating range.

Figure 3. (Left) Numerical Reults Before and After SmartDO Optimization. (Right) Geometry Shape of the Blades Before and After SmartDO Optimization.

Figure 4. Performance Curves Before and After SmartDO Optimization.

In addition to the commonly usage of optimization for complex problems, SmartDO can also be applied on many different types of analysis and calculations. Taking this newsletter as an example, by altering design conditions, SmartDO can analyze whether the original design could potentially surpass its limits and generate meaningful directions for improvement.

For more information about SmartDO, please contact us.

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FEA-Opt Technology Co. Ltd. is an international RD/Consultancy/CAE and Software firm. We provide superior RD/consultancy services to our customers, and customized solutions for each customer's special need.

SmartDO, our flagship product, is the leader of Smart Global Optimization Technology. Capable of Direct Global Search for both Gradient-Based and GA-Based methodology. For details about SmartDO, please visit our web site at