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Shape optimization of two-dimensional cavitators in supercavitating flows, using NSGA II algorithm 总被引：1，自引：0，他引：1
The reduction of energy consumption of high speed submersible bodies is an important challenge in hydrodynamic researches. In this paper, shape optimization of two-dimensional cavitators in supercavitating flows is studied. A two dimensional supercavitation potential flow passes a symmetric two dimensional cavitator, which is placed perpendicular to the flow in a channel of infinite length and immediately a cavity is formed behind the cavitator. This is because of the generation of a gas or vapor cavity between the body and the surrounding liquid due to the change in a high speed flow direction passing the cavitator. Drag force acting on this supercavitating body dictates the thrust requirements for the propulsion system, to maintain a required cavity at the operating speed. Therefore, any reduction in the drag force, by modifying the shape of the cavitator, will lead to decrease this force. This study concentrates on the optimization of two dimensional cavitators in order to decrease drag coefficient for a specified after body length and velocity in a potential flow. To achieve this goal a multi-objective optimization problem is defined to optimize cavitator shapes in supercavitating flow. The so-called NSGA II (Non-dominated Sorting Genetic Algorithm) algorithm is used as an optimization method. Design parameters and constraints are obtained according to supercavitating flow characteristics and cavitator modeling and objective functions are generated using Linear Regression Method. The obtained results are compared with other classic optimization methods, like the weighted sum method, for validation. 相似文献
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R. Shafaghat S.M. HosseinalipourI. Lashgari A. Vahedgermi 《Applied Ocean Research》2011,33(3):193-198
The reduction of energy consumption for high speed submersible bodies is an important challenge in hydrodynamic researches. Supercavitation is a hydrodynamic process in which a submerged body gets enveloped in a layer of gas. As the density and viscosity of the gas is much lower than that of seawater, skin friction drag can be reduced considerably. If the nose of the body (cavitator) has a proper shape, the attendant pressure drag remains at a very low value, so the overall body drag reduces significantly. Total drag force acting on the supercavitating self-propelled projectiles dictates the amount of fuel consumption and thrust requirements for the propulsion system to maintain a required cavity at the operating speed. Therefore, any reduction in the drag coefficient, by modifying the shape of the cavitator to achieve optimal shape, will lead to a decrease of this force. The main objective of this study is to optimize the axisymmetric cavitator shape in order to decrease the drag coefficient of a specified after-body length and body velocity in the axisymmetric supercavitating potential flow. To achieve this goal, a multi-objective optimization problem is defined. NSGA II, which stands for Non-dominated Sorting Genetic Algorithm, is used as the optimization method in this study. Design parameters and constraints are obtained according to the supercavitating flow characteristics and cavitator modeling. Then objective functions will be generated using the Linear Regression Method. The results of the NSGA II algorithm are compared with those generated by the weighted sum method as a classic optimization method. The predictions of the NSGA II algorithm seem to be excellent. As a result, the optimal cavitator’s shapes are similar to a cone. 相似文献
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Poro A. Halavati A. Lashgari E. Davoudi F. Gardi A. GholizadehSoghar K. Dashti Y. Mohammadizadeh F. Hedayatjoo M. 《Astronomy Reports》2021,65(7):543-551
Astronomy Reports - We performed the first light curve analysis of GW Leo and a new ephemeris is obtained for QT Boo. The light curve investigation also yields that the system GW Leo is a contact W... 相似文献
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Zafarani Hamid Jafarian Yaser Eskandarinejad Alireza Lashgari Ali Soghrat Mohammad Reza Sharafi Hassan Afraz-e Haji-Saraei Masoud 《Natural Hazards》2020,103(2):1783-1805
Natural Hazards - A strong earthquake occurred on November 12, 2017, in Sarpol-e Zahab city, western Iran, with the moment magnitude ( $$M_{{\text{w}}}$$ ) of 7.3 and a focal depth of... 相似文献
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Poro A. Davoudi F. Alicavus F. Khakpash S. Esmer E. M. Basturk O. Lashgari E. Rahimi J. Aladag Y. Aksaker N. Boudesh A. Ghanbarzadehchaleshtori M. Akyuz A. Modarres S. Sojoudizadeh A. Tekes M. Solmaz A. 《Astronomy Letters》2021,47(6):402-410
Astronomy Letters - The first analysis of the photometric observation in BVR filters of a W UMa type binary system BQ Ari was performed. Light curve analysis was performed using... 相似文献
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