Effect of 3D Shape of Pump-Turbine Runner Blade on Flow Characteristics in Turbine Mode

Abstract

The effect of blade spatial profiling with the help of tangential blade lean of Francis pump-turbine runner with heads up to 200 m on the flow structure and energy characteristics was numerically investigated. A flow part model of Francis pump-turbine of the Dniester pumped storage plant was adopted as original version. Two new blade systems were designed, which differed from the original version by mutual position of cross-sections in tangential direction: with positive and negative lean, while the shape of the cross-sections themselves remained unchanged. Modeling of the viscous incompressible flow in calculation domain, which contains one channel of the guide vane and the runner, for three variants of flow parts, was performed using the IPMFlow software based on numerical integration of the Reynolds equations with an additional term containing artificial compressibility. To take into account the turbulent effects, the SST differential two-parameter turbulence model of Menter is applied. Numerical integration of the equations is carried out using an implicit quasi-monotonic Godunov scheme of second order accuracy in space and time. The study was carried out for models with runner diameter of 350 mm in a wide range of guide vane openings at reduced rotation frequencies corresponding to the minimal, design and maximal heads of the station. A comparison of pressure fields and velocity vectors in the runners, pressure graphs on runner blades, distribution of velocity components at inlet to a draft tube, and efficiency of three variants of flow parts are presented. It was concluded that calculation domain with the new RK5217M2 runner with negative tangential lean has the best characteristics. An experimental study of three runners on a hydrodynamic stand are planned

Experimental Studies of Pressure Pulsations in Draft Tube Diffuser of Pump-Turbine Models for Heads up to 200 m

“…At the fi rst stage, using the IPMFlow software package [33] developed at IMEP, a numerical stu - dy of the viscous fl ow of an incompressible fl u id was carried out for three options of runners in a wi de range of operation in turbine mode [34]. The IPMFlow software package allows for nume ri cal studies in various fl ow parts [35,36] using modern mathematical methods [37,38].…”

The method for design of combined electromagnetic shield for overhead power lines magnetic field

“…A sufficient condition for the existence of a saddle point is a change in the sign of the gradient  X f when passing the minimum point from minus to plus, and a change in the signs of the gradient   f when passing the maximum point from plus to minus [44][45][46][47]. These conditions can be formulated as the positive definiteness H X >0 of the matrix of second derivatives -the Hessian matrix with respect to the choice of parameters X, and the negative definiteness H  0 of the Hessian matrix with respect to the parameters δ, i.e.…”

Optimization of spatial arrangement of magnetic field sensors of closed loop system of overhead power lines magnetic field active silencing

“…The disadvantage of the open-loop control algorithm for the silencing windings is its relatively low efficiency of silencing the initial magnetic field [41][42][43][44][45][46][47]. In particular, with an open-loop control algorithm, it is impossible silencing for changes in the magnetic field induction inside the silencing spase, due to the presence of internal sources of magnetic field, as well as in the process of inevitable changes in the parameters of the system of active silencing control object during its operation [39,40].…”