Abstract:Centrifugal compressors are required to increase their operating range and efficiency, which are limited at low mass flow rates by the rotating stall and surge. This paper presents a surrogate-based multi-objective optimization of a centrifugal compressor to improve its efficiency and stall margin. Curvatures of the blade, the impeller shroud, and the diffuser hub are selected as optimization parameters since they influence highly both the efficiency and the stall limit. The implemented optimization procedure … Show more
“…Figure 7.Overview of the computation domain and mesh of the point 1 design.Figure 8.CFD and experimental performance of the LSCC. 4 CFD: computational fluid dynamics; Exp: experimental.…”
Section: Resultsmentioning
confidence: 99%
“…The CFD approach was firstly validated by comparing its outcomes with experimental measurements as shown in Figure 8. Details of the CFD approach are given in Khalfallah et al 4 and summarized here. Many steady simulations are performed for different mass flow rates since this type of simulation is shown to be able to predict correctly aerodynamic performance inside the design range.…”
Section: Application Of the Proposed Optimization Methodsmentioning
confidence: 99%
“…Many steady simulations are performed for different mass flow rates since this type of simulation is shown to be able to predict correctly aerodynamic performance inside the design range. 4 For steady simulations, the computational domain consists in just one passage of the three sub-domains of the compressor (inlet, impeller, and diffuser) as shown in Figure 7. The impeller is simulated in a rotating reference frame where the inlet and the diffuser are simulated in an absolute reference.…”
Section: Application Of the Proposed Optimization Methodsmentioning
confidence: 99%
“…In fact, even in the detailed phase, CFD is usually combined with approximation models (meta-models or surrogates) in order to reduce this unbearable workload. 4 Even though this final phase of design can improve the PD quality, it was shown that both the quality and the cost of the final design depends a lot on that of the PD. For instance, a PD process can take up to 25-30% of the total design time.…”
Preliminary design of centrifugal compressors is an emphasized step, which initiates the design process. Even with the use of quick analysis methods such as one-dimensional models, preliminary design still occupies a substantial part of the total design time. Among the factors that can lengthen this time or even cause the design failure is the inappropriate selection of the design input parameters. The present paper proposes a methodology to generate optimal inputs for the preliminary design, which reduces the design time and optimizes its overall performance. This is achieved, firstly, by performing an aerothermodynamic analysis that defines the appropriate input parameters, which will be used by a preliminary design code. This analysis has allowed identifying three pilot parameters (inlet relative Mach number, work input factor, and slip factor) to guide the generation of adequate input parameters. This input parameter generator, which reduces considerably the failure rate, is then exploited efficiently in an optimization process considering the pilot parameters as decision variables. Therefore, the proposed input parameter generator is coupled with a preliminary design code and an optimization algorithm. The proposed input parameter generator was validated on four existing compressors, showing a gain of more than 90% of the design time. Mainly, the proposed optimization has created a preliminary design trade-off having the target requirements and with optimized off-design performance.
“…Figure 7.Overview of the computation domain and mesh of the point 1 design.Figure 8.CFD and experimental performance of the LSCC. 4 CFD: computational fluid dynamics; Exp: experimental.…”
Section: Resultsmentioning
confidence: 99%
“…The CFD approach was firstly validated by comparing its outcomes with experimental measurements as shown in Figure 8. Details of the CFD approach are given in Khalfallah et al 4 and summarized here. Many steady simulations are performed for different mass flow rates since this type of simulation is shown to be able to predict correctly aerodynamic performance inside the design range.…”
Section: Application Of the Proposed Optimization Methodsmentioning
confidence: 99%
“…Many steady simulations are performed for different mass flow rates since this type of simulation is shown to be able to predict correctly aerodynamic performance inside the design range. 4 For steady simulations, the computational domain consists in just one passage of the three sub-domains of the compressor (inlet, impeller, and diffuser) as shown in Figure 7. The impeller is simulated in a rotating reference frame where the inlet and the diffuser are simulated in an absolute reference.…”
Section: Application Of the Proposed Optimization Methodsmentioning
confidence: 99%
“…In fact, even in the detailed phase, CFD is usually combined with approximation models (meta-models or surrogates) in order to reduce this unbearable workload. 4 Even though this final phase of design can improve the PD quality, it was shown that both the quality and the cost of the final design depends a lot on that of the PD. For instance, a PD process can take up to 25-30% of the total design time.…”
Preliminary design of centrifugal compressors is an emphasized step, which initiates the design process. Even with the use of quick analysis methods such as one-dimensional models, preliminary design still occupies a substantial part of the total design time. Among the factors that can lengthen this time or even cause the design failure is the inappropriate selection of the design input parameters. The present paper proposes a methodology to generate optimal inputs for the preliminary design, which reduces the design time and optimizes its overall performance. This is achieved, firstly, by performing an aerothermodynamic analysis that defines the appropriate input parameters, which will be used by a preliminary design code. This analysis has allowed identifying three pilot parameters (inlet relative Mach number, work input factor, and slip factor) to guide the generation of adequate input parameters. This input parameter generator, which reduces considerably the failure rate, is then exploited efficiently in an optimization process considering the pilot parameters as decision variables. Therefore, the proposed input parameter generator is coupled with a preliminary design code and an optimization algorithm. The proposed input parameter generator was validated on four existing compressors, showing a gain of more than 90% of the design time. Mainly, the proposed optimization has created a preliminary design trade-off having the target requirements and with optimized off-design performance.
“…The results have proved that the methods have the potential to satisfy industrial design needs. The commonly used surrogate models in these studies include Kriging [7,8], radial basis function (RBF) [9], artificial neural networks (ANNs) [10], polynomial response surface (PRS) [11], and support vector regression (SVR) [12]. The accuracy of surrogate models has a great influence on optimization results and may lead to the failure of optimization.…”
A centrifugal compressor is required to increase aerodynamic efficiency, ensure structural integrity, and reduce processing costs. This paper presents a dimension reduction technique based on proper orthogonal decomposition (POD) in combination with an adaptive sampling method to reduce computational costs. Design of experiment (DOE) is first used to choose initial sampling points. Then, parts of the sampling points are selected to format the snapshot matrix. Subsequently, the number of principal components to be retained is determined after POD analysis. An adaptive sampling point adding approach is used to increase new sampling points. The approach places more points around the regions of initial optimum designs by learning the information from previous data through POD analysis. Finally, the POD coefficients are selected to act as new design variables in the following multidisciplinary design optimization process. The method is first tested by three mathematical benchmark functions. The proposed method is then used to optimize a centrifugal compressor, of which the results are verified by tests. A normalized isentropic efficiency improvement of 3.7% and 3.0% in the maximum speed state and cruise state has been obtained after optimization. Additionally, the processing costs are reduced by about 30% owing to the number of blades reduced.
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