Engineering, Technology & Applied Science Research Vol. 6, No. 4, 2016, 1102-1107 1102 www.etasr.com Dragan et al.: A Comparative Analysis Between Optimized and Baseline High Pressure Compressor Stages A Comparative Analysis Between Optimized and Baseline High Pressure Compressor Stages Using Tridimensional Computational Fluid Dynamics Valeriu Dragan Computational Fluid Dynamics Department NRDI Comoti Bucharest, Romania valeriu.dragan@comoti.ro Ion Malael Computational Fluid Dynamics Department NRDI Comoti Bucharest, Romania ion.malael@comoti.ro Bogdan Gherman Computational Fluid Dynamics Department NRDI Comoti Bucharest, Romania bogdan.gherman@comoti.ro Abstract—Re-vamping of industrial turbo-machinery is commonplace in the oil and gas industry in applications where subterranean combustion is used for oil extraction. The current case study refers to such an industrial compressor re-vamping, using a state of the art 3D fully viscous CFD methodology coupled with artificial neural networks (ANNs) and genetic algorithms (GA). The ANN is used to establish correlations within a database of CFD simulations of geometrical variations of the original rotor and the GA uses those correlations to estimate an optimum. The estimate is then tested with the same CFD method and the results are fed back into the database, increasing the accuracy of the ANN correlations. The process is reiterated until the optimum estimated by the GA is confirmed with the CFD simulations. The resulting geometry is superior to the original in terms of efficiency and pressure ratio as well as the range of stabile operation, as confirmed by the successful implementation in the field. In this paper we present an analysis of why the optimized geometry achieves superior performances to the original one. Further work will present comparison between the detailed experimental data and CFD. Keywords-optimization; CFD; turbomachinery; centrifugal compressor; artifficial neural network; genetic algorithm I. INTRODUCTION Current competiveness requirements in the turbo-machinery industry call for increased operational qualities of the final product. Using modern CFD methods, a tailored made solution, which considers more than one criteria, can be obtained and solution customization can be obtained. This paper presents a re-vamping, optimization case study for a high pressure compressor stage used in the petrol industry. The design theme demanded for a 10 percent increase in mass flow as well as an increase in the isentropic efficiency while maintaining the same outlet diameter, height and rotor aspect ratio. From the start this will imply that the flow coefficient will be increased and that the specific wheel speed is decreased, making it less optimal according to traditional design theories. Since neither the slip factor nor the jet-wake paradigms allow the design of such a stage, unless the models incorporate more elaborate stochastic models, the case study must be carried out using fully viscous numerical simulations. In this particular case, the optimization study was carried out in two steps, firstly using an in-house goal driven method and finally the Numeca Design 3D commercial package. In the first re-vamping stage, both the rotor and stator were reshaped using conventional 2D methods coupled with the in- house stochastic correlations. This process of the stage re- design also incorporates a primary optimization of the two blade rows. Version 15 (V15) represents the preliminary result of the re -vamping with the Euler in-house code [1]. Intuitively, in designing V15 two key aspects were targeted, namely maintaining the specific speed at the highest possible value while preventing flow separation and, secondly, diminishing the machine Mach number – which was thought as a source of loss. Both those targets were proven to be misguided since V25 actually has a higher machine Mach number and a lower specific speed. Paradoxically it seems that minimizing and maximizing isol