On the performance of a cascade of turbin rotor tip section blading in wet steam Part 4: Droplet measurements

1999 ◽  
Vol 213 (4) ◽  
pp. 343-353 ◽  
Author(s):  
F Bakhtar ◽  
S. Y. Rassam ◽  
G Zhang
Keyword(s):  
The State ◽  
Saturation Line ◽  
Light Extinction ◽  
Wet Steam ◽  
Two Phase ◽  
Blow Down ◽  
Phase Mixture ◽  
State Path

In the course of expansion of steam in turbines the state path crosses the saturation line and the fluid nucleates to become a two-phase mixture. These conditions can be reproduced under blow-down conditions by the equipment employed. This paper is the fourth of a set describing an investigation into the performance of a cascade of rotor tip section blading in wet steam and presents the results of droplet measurements which have been carried out by light extinction.

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.

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.

Theoretical Treatments of Two-Dimensional Two-Phase Flows of Steam and Comparison with Cascade Measurements

2005 ◽  
Vol 219 (12) ◽  
pp. 1335-1355 ◽  
Author(s):  
F Bakhtar ◽  
A J White ◽  
H Mashmoushy
Keyword(s):  
Numerical Methods ◽  
Nucleation And Growth ◽  
Nucleation Theory ◽  
Two Dimensional ◽  
Wet Steam ◽  
Calculation Methods ◽  
Two Phase ◽  
Droplet Nucleation ◽  
Condensing Flows ◽  
State Path

During the course of expansion of steam in turbines, the state path crosses the saturation line and hence subsequent turbine stages operate with wet steam. These stages have lower thermodynamic efficiencies than those operating in the superheated region, and currently the phenomena contributing to the increased losses are not fully understood. The development of the nucleation theory has opened the way for the study of condensing flows in turbines. As, with the advances in numerical methods, the equations describing droplet nucleation and growth rates can be combined with the field conservation equations and the set treated numerically, which allows the behaviour of complex nucleating and wet steam flows in turbines to be analysed. This paper outlines and reviews wet steam calculation methods and discusses comparisons between numerical and experimental results. For the most part, the comparisons presented are based on work of the authors and their co-workers, but some more recent calculations by other investigators are also included.

On the performance of a cascade of improved turbine nozzle blades in nucleating steam – Part 3: theoretical analysis

2011 ◽  
Vol 225 (7) ◽  
pp. 1649-1671 ◽  
Author(s):  
F Bakhtar ◽  
M Y Zamri
Keyword(s):  
Heat Transfer ◽  
Liquid Phase ◽  
Internal Heat ◽  
Aerodynamic Performance ◽  
Blade Profile ◽  
Two Phase ◽  
Phase Mixture ◽  
Internal Heat Transfer ◽  
State Path ◽  
Nozzle Blade

This article is the last of a set and describes the analysis of the performance of an improved steam turbine nozzle blade profile. In the course of expansion of steam in turbines, the state path crosses the saturation line, the fluid nucleates to 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. Following earlier studies of typical profiles in nucleating steam, the performance of a new design of blades is examined. A substantially improved aerodynamic performance is achieved by the new design. The effect of heat release by condensation in increasing the aerodynamic losses is not intrinsic to the system and can be avoided by design but the losses resulting from the internal heat transfer are intrinsic and considerable.

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 1: Surface pressure distributions

2009 ◽  
Vol 223 (8) ◽  
pp. 1903-1914 ◽  
Author(s):  
F Bakhtar ◽  
Z A Mamat ◽  
O C Jadayel ◽  
M R Mahpeykar
Keyword(s):  
Surface Pressure ◽  
Pressure Measurements ◽  
Flow Conditions ◽  
Mixture Formation ◽  
Two Phase ◽  
Blow Down ◽  
Pressure Distributions ◽  
Flow Visualizations ◽  
State Path ◽  
Nozzle Blade

This article is the first of a set and describes the results of surface pressure measurements and flow visualizations in a cascade of improved steam turbine nozzle blade profiles. In the course of expansion of steam in turbines, the state path crosses the saturation line and the fluid nucleates to become a two-phase mixture. Formation and subsequent behaviour of the liquid lowers the performance of turbine wet stages. Turbine two-phase flow conditions can be reproduced satisfactorily under blow-down conditions for systematic study. Following earlier studies of some typical profiles the performance of a new design of blades is presented. A substantially improved aerodynamic performance has been achieved by the new profile.

On the Performance of a Cascade of Turbine Rotor Tip Section Blading in Nucleating Steam: Part 1: Surface Pressure Distributions

1995 ◽  
Vol 209 (2) ◽  
pp. 115-124 ◽  
Author(s):  
F Bakhtar ◽  
M Ebrahimi ◽  
R A Webb
Keyword(s):  
Surface Pressure ◽  
Turbine Rotor ◽  
Pressure Measurements ◽  
Flow Conditions ◽  
Mixture Formation ◽  
Two Phase ◽  
Blow Down ◽  
Pressure Distributions ◽  
Phase Mixture

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. To reproduce turbine nucleating and wet flow conditions requires a supply of supercooled steam which can be achieved under blow-down conditions by the equipment employed. The performance of a cascade of rotor tip section blading in nucleating steam has been studied. The results of the surface pressure measurements are described in the paper.

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