On the performance of a cascade of turbine rotor tip section blading in nucleating steam Part 3: Theoretical treatment

Abstract

During the course of expansion in turbines, steam first supercools and then nucleates to become a two-phase mixture. Formation and subsequent behaviour of the liquid lower the performance of turbine wet stages. This is an area where greater understanding can lead to improved design. This paper describes the theoretical part of an investigation into nucleating flows of steam in a cascade of turbine rotor tip section blading. The main flow field is regarded as inviscid and treated by the time-marching technique modified to allow for two-phase effects. The viscous effects are assumed to be concentrated in boundary layers which are treated by the integral method. Comparisons are carried out with the experimental measurements presented in the earlier parts of the paper and the agreement obtained is good.

Effects of non-equilibrium condensation on aerodynamics of the flow field in a steam turbine cascade

“…To validate the present in-house code, the experimental data reported by Bakhtar and Mahpeykar [7] have been used. The boundary conditions for the current numerical simulation have been chosen as identical to those in the experimental test, such as the in ow direction ( ) is 38 and the in ow stagnation pressure Figure 2.…”

“…At the inlet section, the wetness fraction = 0; at the outlet section, the back-pressure P b = 42:7 kPa. Comparison of the pressure ratio on the suction and pressure surfaces between numerical and experimental results [7]; distribution of pressure ratio on the pressure and suction surfaces. The present computation is performed with grid size of 498 65.…”

“…He studied the e ects of inlet superheating and outlet Mach number on the trailing edge shock structure. Bakhtar et al [7][8][9] carried out some experiments to study two-phase nucleating steam ow in a blade passage. Also, they performed a comparative study of the treatment of two-dimensional nucleating ows using Runge-Kutta and Denton's methods [10].…”

A Unified CFD Based Approach to a Variety of Condensation Processes in a Viscous Turbulent Wet Steam Flow

“…Implicit boundary conditions for the variations of variables are incorporated. The basic solver strategy employs a Gauss-Seidel relaxation procedure, sequentially applied to the systems of Equations [1] and [8]. In addition Newton sub-iterations are used at each global time step to increase stability and reduce linearization errors.…”

Study on water extraction of hollow stationary blade under wet steam flow conditions

“…The additional thermodynamics loss is caused by nonequilibrium condensing flow where the rapid-expansion pure steam will be in supercooled state, and the heat transfer process is anisothermal 2 . Many experimental and numerical investigations on nonequilibrium condensing flow have been conducted for years, where the classical condensation theory and the growth rate of water droplets have been validated and studied in Laval nozzles 3-5 and turbine cascades [6][7][8] . Moreover, experiments have been carried on in model or full-scale LP steam turbines…”