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In this paper, the author tried to find out how clearance between impeller and tongue would affect the pressure fluctuation. By changing the diameter of the impeller, six transient simulations of a centrifugal pump were conducted. Data from different monitoring points were recorded and analyzed. The result shows that pressure fluctuation decreases with the increasing of the clearance. But the high-frequency...
Comparative studies of two stators in a highly loaded axial compressor stage were investigated experimentally in a Low-speed Large-scale Axial compressor test Facility. The two stators, one was designed with conventional radial stacking method called as Stator A, the other one was designed with positive dihedral near the two endwalls based on Stator A, i.e. bowed stator, called as Stator B, were assembled...
Large scale reciprocating compressor in petrochemical process is usually operated under partial load based on the system condition, and adjusted its capacity by controlling suction valve is an efficient method for energy saving. In this paper, a mathematical model coupled suction valve and actuator is built to describe the dynamic response process of suction valve and actuator and the response time...
The temporal and time-mean characteristics of the secondary flow in a linear turbine cascade are investigated using an in-house time-resolved particle image velocimetry (TR-PIV) system and the analysis technique of power spectrum distribution (PSD). The experiments are carried out in a low-speed water tunnel, which is made of scaled-up GE-E3 high pressure blades to form a linear turbine cascade. The...
This paper presents the methods used in hydraulic development of the hydraulic turbine for Minzhi power station in Sichuan province of China, which include the layout of hydraulic parameters, the geometry design for each component and CFD numerical analysis for the whole turbine. The numerical predictions of the hydraulic performance, e.g. energy, cavitation, pressure pulsation etc., are validated...
Three-dimensional simulation was performed for the solid-liquid turbulent flow in swept-back sewage centrifugal pump with particle model and simple-c algorithm by ANSYS-CFX software. k - ε double turbulence model was applied to predict the liquid-phase, and an algebraic named the dispersed phase zero equation was adopted to predict the solid-phase. Free slip wall conditions were used for mass and...
The hydraulic losses of hydraulic turbine are mainly distributed in the volute, stay vane, runner and draft tube. The theories and practices show that the hydraulic loss of stay vane occupies a large proportion in total in low specific speed turbine and this problem is more serious in super low specific speed turbine. The super low specific speed Francis turbine, which has been widely used to drive...
CFD simulations on flow field of centrifugal pumps at shutoff are generally performed by means of minor-flow assumption, which are different from real operating conditions and hard to well predict pump performances at shutoff. In this paper, therefore, the zero-flow boundary condition was taken to proceed to a numerical simulation of unsteady flow for the type IS125 centrifugal pump. The pump performances...
The fault of hydropower unit is affected by many factors, it is difficult to find the correspondent fault symptoms and causes through the theoretical analysis. Considering the disadvantages of BP neural network, such as slow convergence rate and getting into local extremum, the initial parameters are optimized by the improved artificial fish swarm algorithm and the model for fault diagnosis is established...
Reaction factor should be considered in the hydraulic design of centrifugal pump impeller due to a great effect on blade shape of the centrifugal pump. The relationship between the geometric parameters of centrifugal pump impeller and reaction factor was built, based on the definition of reaction factor; meanwhile mathematical methods was adopted to demonstrate the relationship between reaction factor...
For the characteristics of complicated system structure and quantities of uncertain factors in hydropower units fault diagnosis, Bayesian network is introduced into the diagnosing analysis, a fault diagnosis system of hydropower units is built based on Bayesian network. Noisy Or model is introduced into Bayesian network system for overcoming the shortcomings of Bayesian network like considerable numbers...
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