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| 1 | Numerical investigation on the “S” characteristics of a reduced pump turbine model显示文摘The performance of a reversible pump turbine with S-shaped characteristics is of great importance to the transition processes such as start-up and load rejection. In order to predict the S-shaped curve accurately and develop a reliable tool for design improvement, a shear stress transport model (SST) with various numerical schemes for pressure term in the governing equation was investigated in a whole pump turbine including spiral casing, stay vanes, guide vanes, runner and draft tube. Through the computation, it was shown that different zones in the curve should employ different schemes to get the solution converged. Comparison of discharge-speed performance showed that good correspondence is got between experimental data and CFD results. Based on this, internal flow analysis was carried out at three typical operating points representing turbine mode, shut-off mode and reversible pump mode, respectively. According to the flow field concerned, the mechanism for the speed-no-load instability was explained, which provides good guidelines to take countermeasures in future design. | WANG LeQin YIN JunLian JIAO Lei WU DaZhuan QIN DaQing | 2011 | Science China(Technological Sciences)2011,54,5: | 20 |
| 2 | Investigation of the unstable flow phenomenon in a pump turbine显示文摘Instability of pump turbine with S-shaped curve is characterized by large fluctuations of rotational speed during the transient processes.For investigating this phenomenon,a numerical model based on the dynamic sliding mesh method(DSSM)is presented and used to numerically solve the 3D transient flow which is characterized by the variable rotation speed of runner.The method is validated by comparison with measured data for a load rejection process in a prototype pump turbine.The results show that the calculated rotation speed agrees well with the experimental data.Based on the validated model,simulations were performed for the runaway process using an artificially assumed operating condition under which the unstable rotation speed is expected to appear.The results confirm that the instability of runner rotational speed can be effectively captured with the proposed method.Presented results include the time history profiles of unit flow rate and unit rotating speed.The internal flow characteristics in a typical unstable period are discussed in detail and the mechanism of the unstable hydraulic phenomenon is explained.Overall,the results suggest that the method presented here can be a viable alternative to predict the dynamic characteristics of pump turbines during transient processes. | YIN JunLian WANG DeZhong WALTERS D.Keith WEI XianZhu | 2014 | Science China(Physics,Mechanics & Astronomy)2014,57,6: | 8 |
| 3 | Review on Applications of 3D Inverse Design Method for Pump显示文摘The 3D inverse design method,which methodology is far superior to the conventional design method that based on geometrical description,is gradually applied in pump blade design.However,no complete description about the method is outlined.Also,there are no general rules available to set the two important input parameters,blade loading distribution and stacking condition.In this sense,the basic theory and the mechanism why the design method can suppress the formation of secondary flow are summarized.And also,several typical pump design cases with different specific speeds ranging from centrifugal pump to axial pump are surveyed.The results indicates that,for centrifugal pump and mixed pump or turbine,the ratio of blade loading on the hub to that on the shroud is more than unit in the fore part of the blade,whereas in the aft part,the ratio is decreased to satisfy the same wrap angle for hub and shroud.And the choice of blade loading type depends on the balancing of efficiency and cavitation.If the cavitation is more weighted,the better choice is aft-loaded,otherwise,the fore-loaded or mid-loaded is preferable to improve the efficiency.The stacking condition,which is an auxiliary to suppress the secondary flow,can have great effect on the jet-wake outflow and the operation range for pump.Ultimately,how to link the design method to modern optimization techniques is illustrated.With the know-how design methodology and the know-how systematic optimization approach,the application of optimization design is promising for engineering.This paper summarizes the 3D inverse design method systematically. | YIN Junlian WANG Dezhong | 2014 | Chinese Journal of Mechanical Engineering2014,27,3: | 1 |
| 4 | Experimental study on the hydraulic characteristics of vortex diodes显示文摘Vortex diode,as an important component in power fluidics,has been used in nuclear reprocessing engineering where it is desirable to avoid pumps with moving parts.The performance of the fluidic system depends on the matched design parameters of vortex diodes and the supporting facilities.However,no clear guidelines for design and optimization of vortex diodes system are available.Therefore,we carried out detailed experimental study on hydraulic characteristics of the vortex diodes system with changeable parameters to evolve such guidelines.The study covered a wide range of a vortex diode and vortex diodes system.The variation of averaged discharge and volumetric efficiency in respect to air supply pressure,liquid level of water tank and liquid level stroke of gas-liquid energy converter was studies.The experimental results were analyzed to develop design guidelines.The guidelines are shown to be useful for obtaining the design parameters that would yield the desired hydrau- lic performance for the required operating conditions. | JIAO Lei CHEN CongNan LIU JinTao YIN JunLian WANG LeQin | 2011 | Science China(Technological Sciences)2011,54,2: | 0 |