scholarly journals Prediction of two-phase mixture level and hydrodynamically-controlled dryout under low flow conditions. [PWR]

1980 ◽  
Author(s):  
K. H. Sun ◽  
R. B. Duffey ◽  
C. M. Peng
Keyword(s):  
Low Flow ◽  
Flow Conditions ◽  
Two Phase ◽  
Phase Mixture

On the performance of a cascade of turbine rotor tip section blading in wet steam Part 3: Wake traverses

1997 ◽  
Vol 211 (8) ◽  
pp. 639-648 ◽  
Author(s):  
F Bakhtar ◽  
H Mashmoushy ◽  
O C Jadayel
Keyword(s):  
Liquid Phase ◽  
Two Phase Flow ◽  
Turbine Rotor ◽  
Phase Flow ◽  
Wet Steam ◽  
Flow Conditions ◽  
Two Phase ◽  
Blow Down ◽  
The Third ◽  
Phase Mixture

During the course of expansion of steam in turbines the fluid first supercools and then nucleates to become a two-phase mixture. The liquid phase consists of a large number of extremely small droplets which are difficult to generate except by nucleation. To reproduce turbine two-phase flow conditions requires a supply of supercooled vapour which can be achieved under blow-down conditions by the equipment employed. This paper is the third of a set describing an investigation into the performance of a cascade of rotor tip section profiles in wet steam and presents the results of the wake traverses.

On the performance of a cascade of turbine rotor tip section blading in wet steam Part 1: Generation of wet steam of prescribed droplet sizes

1997 ◽  
Vol 211 (7) ◽  
pp. 519-529 ◽  
Author(s):  
F Bakhtar ◽  
H Mashmoushy ◽  
J R Buckley
Keyword(s):  
Superheated Steam ◽  
Turbine Rotor ◽  
Phase Flow ◽  
Wet Steam ◽  
Flow Conditions ◽  
Two Phase ◽  
Lower Efficiency ◽  
Blow Down ◽  
Droplet Sizes ◽  
Phase Mixture

During the course of expansion in turbines steam nucleates to become a two-phase mixture consisting of a very large number of extremely small droplets carried by the vapour. Turbine stages operating in a two-phase regime have a lower efficiency than those working on superheated steam. To reproduce turbine two-phase flow conditions realistically requires a supply of supercooled steam which can be generated under blow-down conditions by the equipment employed. To generate wet steam the supercooled steam can be passed through a venturi. This paper is one of a set describing an investigation of the performance of a cascade of turbine rotor tip section profiles in wet steam and is concerned with the generation of a supply of wet steam of prescribed droplet sizes for admission to the cascade.

On the performance of a cascade of turbine rotor tip section blading in wet steam Part 2: Surface pressure distributions

1997 ◽  
Vol 211 (7) ◽  
pp. 531-540 ◽  
Author(s):  
F Bakhtar ◽  
H Mashmoushy ◽  
O C Jadayel
Keyword(s):  
Droplet Size ◽  
Surface Pressure ◽  
Turbine Rotor ◽  
Pressure Measurements ◽  
Wet Steam ◽  
Flow Conditions ◽  
Two Phase ◽  
Blow Down ◽  
Pressure Distributions ◽  
Phase Mixture

In the course of expansion in turbines steam nucleates to become a two-phase mixture, the liquid consisting of a very large number of extremely small droplets carried by the vapour. Formation and subsequent behaviour of the liquid lowers the performance of turbine wet stages. To produce turbine nucleating and wet flow conditions realistically requires a supply of supercooled steam which can be achieved under blow-down conditions by the equipment employed. To obtain wet steam, the supercooled vapour generated is passed through a venturi before admission to the cascade. To evaluate the influence of droplet size two separate Venturis have been used in the investigation. The performance of a cascade of rotor tip section blading in wet steam has been studied. This paper is the second of a set and describes the results of the surface pressure measurements.

Influence of Blade Pitch and Number of Blades of a Pump Inducer on Single and Two-Phase Flow Performance

2020 ◽  
Author(s):  
Michael Mansour ◽  
Trupen Parikh ◽  
Dominque Thévenin
Keyword(s):  
High Performance ◽  
Two Phase Flow ◽  
Low Flow ◽  
Phase Flow ◽  
Flow Conditions ◽  
Two Phase ◽  
Phase Mixing ◽  
Part Load ◽  
Two Phases ◽  
Load Conditions

Abstract This study investigates the influence of various inducer configurations upstream of a pump impeller on the single and two-phase flow performance. Three pitch values (P = 0.151, 0.251, and 0.351 m), as well as three different numbers of blades (N = 2, 3, and 4 blades), were studied, leading to a total of 9 different inducer geometries. The main objective of the present study is to analyze and compare the corresponding performances and the two-phase mixing behavior, which is necessary for improving the two-phase pumping ability. 3D steady-state simulations using the Moving Reference Frame (MRF) approach were applied for single-phase flow, while a transient setup using a moving-mesh approach was employed for two-phase simulations. Turbulence was modeled by the Reynolds Stress Model (RSM), whereas the Volume of Fluid (VOF) method was applied to model air-water interactions. The results show that the increase in the number of blades leads to a high performance drop at overload (high-flow) conditions, but only to a slight performance enhancement at part-load (low-flow) conditions. Additionally, the effective flow range of the inducer corresponding to high efficiency becomes narrower for a higher number of blades. Concerning the inducer pitch, at part-load conditions, a lower pitch is slightly beneficial to smoothly suck the flow and damp the low-flow vortices; employing a high pitch at these conditions results in intensified flow vortices, reducing slightly the performance. On the other hand, the blade pitch is very influential for the performance at optimal and overload conditions, where a lower pitch causes flow blockage, leading to significant performance deterioration and a very limited range of applications. Generally, it was found that a modification of the inducer configuration affects the performance much more at overload compared to part-load conditions. Concerning two-phase mixing performance, the highest pitch provides the best mixing since the inducer is able to effectively churn the two phases. Similarly, an increase in the number of blades amplifies the turbulence between the two phases, thus improving mixing. Overall, a higher inducer pitch and a low to moderate number of inducer blades best ensure high performance, wide working range, and efficient two-phase mixing.

An Investigation of Nucleating Flows of Stream in a Cascade of Turbine Blading—Wake Traverses

1994 ◽  
Vol 116 (1) ◽  
pp. 121-127 ◽  
Author(s):  
F. Bakhtar ◽  
M. Ebrahimi ◽  
R. A. Webb
Keyword(s):  
Short Duration ◽  
Two Phase Flow ◽  
Phase Flow ◽  
Flow Conditions ◽  
Two Phase ◽  
Blow Down ◽  
Phase Mixture ◽  
Turbine Blading

During the course of expansion in turbines, steam first supercools and then nucleates to become a two-phase mixture consisting of a very large number of minute droplets suspended in the parent vapor. To reproduce turbine two-phase flow conditions realistically requires a supply of supercooled vapor, which can be achieved under blow-down conditions. This paper is one of a set describing the equipment which has been constructed and the first family of results obtained on a short duration cascade tunnel working on the blow-down principle. The arrangements for traversing downstream of a cascade of nozzle blades and the results obtained are described in the paper.

On the Performance of a Cascade of Turbine Rotor Tip Section Blading in Nucleating Steam: Part 2: Wake Traverses

1995 ◽  
Vol 209 (3) ◽  
pp. 169-177 ◽  
Author(s):  
F Bakhtar ◽  
M Ebrahimi ◽  
B O Bamkole
Keyword(s):  
Two Phase Flow ◽  
Turbine Rotor ◽  
Phase Flow ◽  
Flow Conditions ◽  
Two Phase ◽  
Blow Down ◽  
Phase Mixture

During the course of expansion of steam in turbines the fluid first supercools and then nucleates to become a two-phase mixture. To reproduce turbine two-phase flow conditions requires a supply of supercooled vapour which can be achieved under blow-down conditions by the equipment employed. This paper is the second of a set describing an investigation into the performance of a cascade of rotor tip section profiles in nucleating steam and presents the results of the wake traverses and droplet measurements.

On the performance of a cascade of improved turbine nozzle blades in nucleating steam. Part 2: Wake traverses

2009 ◽  
Vol 223 (8) ◽  
pp. 1915-1929 ◽  
Author(s):  
F Bakhtar ◽  
Z A Mamat ◽  
O C Jadayel
Keyword(s):  
Liquid Phase ◽  
Steam Turbine ◽  
Aerodynamic Performance ◽  
Phase Flow ◽  
Flow Conditions ◽  
Two Phase ◽  
Blow Down ◽  
Phase Mixture ◽  
State Path ◽  
Nozzle Blade

This article is the second of a set and describes the results of wake traverses and droplet measurements in a cascade of steam turbine improved nozzle blade profiles. In the course of expansion of steam in turbines the state path crosses the saturation line, the fluid nucleates become wet, and the succeeding stages have to operate on a two-phase mixture. The formation and subsequent behaviour of the liquid phase lowers the performance of turbine wet stages. To study these problems systematically the turbine two-phase flow conditions need to be reproduced realistically, which can be done under blow down conditions. Following earlier studies of typical profiles in nucleating steam the performance of a new design of blades is presented. A substantially improved aerodynamic performance is achieved by the new profile.

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