China
Africa
Explore chapters and articles related to this topic
Investigation of the hydraulic forces on the radial vibrationof hydro-turbine units
Published in Rodolfo Dufo-López, Jaroslaw Krzywanski, Jai Singh, Emerging Developments in the Power and Energy Industry, 2019
Yong Xu, Xiaoqiang Dang, Yunliang Chen, Bin Wang, Yufang Huang
For convenience, we firstly suppose that there is axisymmetric water flow in the turbine runner. Consequently, the water flow in the turbine runner might be stable relative to the runner blades in a stable operating condition, i.e., the motion of flow would not change over time. In this situation, the movement of water flow in the runner could be expressed by a so called velocity triangle of a hydraulic turbine. Taking a point K in the runner blade for analysis, the velocity triangle of the hydraulic turbine could be drawn as shown in Figure 1. The runner is supposed to move with a uniform velocity u. The absolute velocity of water flow is v, and the water entering the runner with a relative velocity w. The absolute velocity v could be reduced into two mutually perpendicular components, the rotational vu and the meridian velocity vm components. The meridian velocity vm could again be reduced into two mutually perpendicular components, the radial vr and the axial velocity vz components. For a Kaplan unit, the uniform velocity u at point K could be expressed as u=RΩ=2πRn/30 , where n represents the rotational speed of the unit in revolutions per minute, and R denotes the distance between the point K and the center of the shaft. And the meridian velocity vm could be expressed as vm=Q/π(R2−rh2), where Q represents the discharge passing the turbine per second, ignoring the volumetric loss, and rh denotes the radius of the turbine hub.
Performance analysis of a centrifugal pump based on noise
Published in Science and Technology for the Built Environment, 2021
Xinyu Liu, Junjie Liu, Lizhi Jia, Junyi He, Jinxian Zhang
The theoretical calculation of the velocity of the internal flow field of the pump is based on the velocity triangle shown in Figure 5. Figure 5(a) shows the velocity triangle at the inlet and outlet of the impeller blade, which is defined on the basis of three flow components: the relative velocity (ω), absolute velocity (c) and peripheral velocity (u). Figure 5(b) represents the velocity triangle of the fluid moving in the impeller. (Si et al. 2019). The energy conversion inside of the pump is calculated and analyzed based on the Bernoulli equation. The water pressure at the inlet of the pump remains unchanged, and that at the outlet is at atmospheric pressure. Under the premise of a certain pump structure, the energy conversion efficiency inside the volute is constant. Thus, the energy conversion calculation formula in the volute can be simplified, as shown in Equation (2-3). The velocity gradient from the impeller to the volute can be calculated by Equation (2-4).