Development and application of environment-friendly blade adjusting device
Zhang Rentian1,2,3, Deng Dongsheng4, Zhu Honggeng2, Li Longhua3, Yue Xiubin4
1.Jiangsu Surveying and Design Institute of Water Resources Co. Ltd., Yangzhou, Jiangsu 225127, China; 2.College of Hydraulic Science and Engineering, Yangzhou University, Yangzhou, Jiangsu 225009, China; 3.College of Mechanical & Electronics Enginee-ring, Hohai University, Changzhou, Jiangsu 213022, China; 4.Jiangsu Water Supply Co. Ltd. in Eastern Route of S-to-N Water Diversion Project, Nanjing, Jiangsu 210029, China
Abstract：Blade adjusting is a main method for regulating operational conditions of large-size blade adjustable impeller pumps. An environment-friendly blade adjusting device was developed through a combination of mechanical adjusting mechanism with hydraulic one based on an analysis of shortcomings of existing conventional mechanical and hydraulic adjusting mechanisms. For the device, two designs were proposed, in one design the servo-cylinder is positioned between the pump and electric motor shafts, in the other design, the cylinder is positioned on the top of the hub of the impeller. Thus, the leakage of pressured hydraulic oil can be avoided by using reliable seals. A computational model was established to predict hydrodynamic force and moment of fluid on single blade based on 3D CFD technology. As a result, an approach was put forward in which the cylinder diameter and its operating pressure can be determined by means of a prescribed blade setting angle and predicted hydrodynamic moments at various operating points of pump. Additionally, the structure and governing principle of the conventional oil receptor head were updated and improved; and an oil receptor head with servo-cylinder, pressure control valve and digital proportional valve was innovated successfully. A 4‰ control accuracy has been reached for the device, thus an open/closed-loop control can be realized to adjust blade angle precisely.
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