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.

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.

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.

Time-Averaged Heat Transfer and Pressure Measurements and Comparison With Prediction for a Two-Stage Turbine

1994 ◽  
Vol 116 (1) ◽  
pp. 14-22 ◽  
Author(s):  
M. G. Dunn ◽  
J. Kim ◽  
K. C. Civinskas ◽  
R. J. Boyle
Keyword(s):  
Surface Pressure ◽  
Space Shuttle ◽  
Three Dimensional ◽  
Stanton Number ◽  
Navier Stokes ◽  
Pressure Measurements ◽  
Two Stage ◽  
Pressure Transducers ◽  
Pressure Distributions ◽  
Main Engine

Time-averaged Stanton number and surface-pressure distributions are reported for the first-stage vane row and the first-stage blade row of the Rocketdyne Space Shuttle Main Engine two-stage fuel-side turbine. These measurements were made at 10, 50, and 90 percent span on both the pressure and suction surfaces of the component. Stanton-number distributions are also reported for the second-stage vane at 50 percent span. A shock tube is used as a short-duration source of heated and pressurized air to which the turbine is subjected. Platinum thin-film gages are used to obtain the heat-flux measurements and miniature silicone-diaphragm pressure transducers are used to obtain the surface pressure measurements. The first-stage vane Stanton number distributions are compared with predictions obtained using a quasi-three dimensional Navier–Stokes solution and a version of STAN5. This same N–S technique was also used to obtain predictions for the first blade and the second vane.

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.

scholarly journals Flow in a Pelton Turbine Bucket: Numerical and Experimental Investigations

2005 ◽  
Vol 128 (2) ◽  
pp. 350-358 ◽  
Author(s):  
Alexandre Perrig ◽  
François Avellan ◽  
Jean-Louis Kueny ◽  
Mohamed Farhat ◽  
Etienne Parkinson
Keyword(s):  
Homogeneous Model ◽  
Free Surface Flow ◽  
Flow Patterns ◽  
Surface Flow ◽  
Experimental Investigations ◽  
Pressure Measurements ◽  
Two Phase ◽  
Pelton Turbine ◽  
Flow Visualizations ◽  
Turbine Bucket

The aim of the paper is to present the results of investigations conducted on the free surface flow in a Pelton turbine model bucket. Unsteady numerical simulations, based on the two-phase homogeneous model, are performed together with wall pressure measurements and flow visualizations. The results obtained allow defining five distinct zones in the bucket from the flow patterns and the pressure signal shapes. The results provided by the numerical simulation are compared for each zone. The flow patterns in the buckets are analyzed from the results. An investigation of the momentum transfer between the water particles and the bucket is performed, showing the regions of the bucket surface that contribute the most to the torque. The study is also conducted for the backside of the bucket, evidencing a probable Coanda interaction between the bucket cutout area and the water jet.

An Investigation of Nucleating Flows of Steam in a Cascade of Turbine Blading

1993 ◽  
Vol 115 (1) ◽  
pp. 128-134 ◽  
Author(s):  
F. Bakhtar ◽  
R. A. Webb ◽  
M. H. Shojaee-Fard ◽  
M. A. Siraj
Keyword(s):  
Experimental Investigation ◽  
Surface Pressure ◽  
Reasonable Agreement ◽  
Experimental Results ◽  
Pressure Measurements ◽  
Experimental Facility ◽  
Blow Down ◽  
Turbine Blading

During the course of expansion in turbines steam first supercools and then nucleates to become a wet mixture. To reproduce turbine nucleating conditions realistically requires a supply of supercooled vapor. This can be achieved under blow-down conditions and an experimental facility for such studies has been constructed. The results of the first experimental investigation of nucleating flows of steam in a cascade of nozzle blading using the equipment are presented. The experimental results presented consist of surface pressure measurements, Mach-Zehnder and shadow photography. Comparisons with theoretical solutions show reasonable agreement.

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.

Steady and Unsteady Surface Pressure Distributions Around Rectangular Prisms With Sharp Edges at Reynolds Number Up to 2.5×106

2006 ◽  
Author(s):  
Annick D’Auteuil ◽  
Guy L. Larose
Keyword(s):  
Reynolds Number ◽  
Turbulent Flow ◽  
Surface Pressure ◽  
Angle Of Attack ◽  
Pressure Measurements ◽  
Oncoming Flow ◽  
Pressure Distributions ◽  
Unsteady Surface Pressure ◽  
Sharp Edges ◽  
Flow Reattachment

The commonly-held assumption that the aerodynamics of rectangular prisms with sharp edges are insensitive to Reynolds number is shown to have limitations. Flow reattachment on the top and/or bottom of the prisms can be related to Reynolds number, Re. Steady and unsteady surface pressure measurements were carried out on nine different rectangular prisms for Re from 0.3×106 to 2.5×106 at several angles of attack, in smooth and turbulent flow. It was observed that the reattachment was dependent on parameters such as fineness ratio, edge treatment, angle of attack, turbulence of the oncoming flow and Reynolds number. Permanent reattachment occurred for prisms with fineness ratio of 4 and fluctuating reattachment took place for rectangular prisms with fineness ratio as low as 2.

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