Influence of Secondary Flow on Turbine Erosion

1989 ◽  
Vol 111 (3) ◽  
pp. 310-314 ◽  
Author(s):  
A. Hamed
Keyword(s):  
Secondary Flow ◽  
Gas Turbines ◽  
Trajectory Analysis ◽  
Three Dimensional ◽  
Axial Flow ◽  
Coal Ash ◽  
Particle Dynamics ◽  
Experimental Measurements ◽  
Material Erosion ◽  
Erosion Intensity

This work presents the results of an investigation conducted to study the effect of secondary flow on blade erosion by coal ash particles in axial flow gas turbines. The particle dynamics and their blade impacts are determined from a three-dimensional trajectory analysis within the turbine blade passages. The blade material erosion behavior and the particle rebound characteristics are simulated using empirical equations derived from experimental measurements. The results demonstrate that the secondary flow has a significant influence on the blade erosion intensity and pattern for the typical ash particle size distribution considered in this investigation.

scholarly journals Effect of Particle Size Distribution on Particle Dynamics and Blade Erosion in Axial Flow Turbines

1990 ◽  
Author(s):  
W. Tabakoff ◽  
A. Hamed ◽  
M. Metwally
Keyword(s):  
Particle Size ◽  
Particle Size Distribution ◽  
Size Distribution ◽  
Gas Turbines ◽  
Three Dimensional ◽  
Axial Flow ◽  
Coal Ash ◽  
Particle Dynamics ◽  
Material Erosion ◽  
Particles Size Distribution

This work presents the results of an investigation conducted to study the effect of coal ash particles size distribution on the particle dynamics, and the resulting blade erosion in axial flow gas turbines. The particle dynamics and their blade impacts are determined from a three dimensional trajectory analysis within the turbine blade passages. The particle rebound conditions and the blade material erosion characteristics are simulated using empirical equations, derived from experimental measurements. For the typical ash particle size distribution considered in this investigation, the results demonstrate that the size distribution has a significant influence on the blade erosion intensity and pattern.

Effect of Particle Size Distribution on Particle Dynamics and Blade Erosion in Axial Flow Turbines

1991 ◽  
Vol 113 (4) ◽  
pp. 607-615 ◽  
Author(s):  
W. Tabakoff ◽  
A. Hamed ◽  
M. Metwally
Keyword(s):  
Particle Size ◽  
Particle Size Distribution ◽  
Size Distribution ◽  
Gas Turbines ◽  
Three Dimensional ◽  
Axial Flow ◽  
Coal Ash ◽  
Particle Dynamics ◽  
Material Erosion ◽  
Effect Of Particle Size

This work presents the results of an investigation conducted to study the effect of coal ash particle size distribution on the particle dynamics, and the resulting blade erosion in axial flow gas turbines. The particle dynamics and their blade impacts are determined from a three-dimensional trajectory analysis within the turbine blade passages. The particle rebound conditions and the blade material erosion characteristics are simulated using empirical equations, derived from experimental measurements. For the typical ash particle size distribution considered in this investigation, the results demonstrate that the size distribution has a significant influence on the blade erosion intensity and pattern.

Effect of Particle Characteristics on Trajectories and Blade Impact Patterns

1988 ◽  
Vol 110 (1) ◽  
pp. 33-37 ◽  
Author(s):  
A. Hamed
Keyword(s):  
Experimental Data ◽  
Trajectory Analysis ◽  
Three Dimensional ◽  
Axial Flow ◽  
Particle Dynamics ◽  
Rotating Blade ◽  
Particle Characteristics ◽  
Sand Particles ◽  
Particle Laden Flows ◽  
Impact Characteristics

This work presents the results of a detailed study of the effect of particle characteristics on the particle dynamics and on the resulting pattern of blade impacts in a two stage axial flow gas turbine operating with particle laden flows. The particle dynamics computations combine the particle-blade impact characteristics, as determined from a three dimensional trajectory analysis with the particle rebound characteristics, which are obtained from experimental data. The results show the pattern of blade impacts in all stationary and rotating blade rows for fly ash and for sand particles. The results demonstrate that drastically different patterns of particle blade impacts are associated with the different particles.

Turbine Erosion Exposed to Particulate Flow

1986 ◽  
Author(s):  
A. Hamed ◽  
W. Tabakoff ◽  
M. L. Mansour
Keyword(s):  
Experimental Data ◽  
Gas Turbine ◽  
Trajectory Analysis ◽  
Three Dimensional ◽  
Axial Flow ◽  
Particulate Flow ◽  
Blade Row ◽  
Material Erosion ◽  
Erosion Equation ◽  
Impact Characteristics

This work presents the results of a detailed study of blade erosion in a two stage axial flow gas turbine. The computations combine particle-blade impact characteristics, as determined from a three dimensional trajectory analysis with blade material erosion equation, which is obtained from experimental data to predict blade erosion. The results show that the pattern and intensity of blade erosion is dependent on the blade row location and that the first rotor is subject to maximum erosion.

Coating Effect on Particle Trajectories and Turbine Blade Erosion

1992 ◽  
Vol 114 (2) ◽  
pp. 250-257 ◽  
Author(s):  
W. Tabakoff ◽  
M. Metwally
Keyword(s):  
Gas Turbine ◽  
Gas Turbines ◽  
Protective Coatings ◽  
Turbine Blades ◽  
Three Dimensional ◽  
Axial Flow ◽  
Coal Ash ◽  
Impact Angle ◽  
Laser Doppler Velocimeter ◽  
Particle Trajectories

Gas turbine engines operating in dusty environments are exposed to erosion and performance deterioration. In order to improve the erosion resistance, nickel and cobalt superalloy blades and vanes are widely used in the hot section of gas turbines. Protective coatings have been used to enhance superalloy resistance to hot erosion. An investigation has been conducted to study coal ash particle dynamics and resulting blade erosion for both uncoated and coated blades of a two-stage axial flow gas turbine. A quasi-three-dimensional flow solution is obtained for each blade row for accurate computation of particle trajectories. The change in particle momentum due to collision with the turbine blades and casings is modeled using restitution parameters derived from three-component laser-Doppler velocimeter measurements. The erosion models for both blade superalloy and coatings are derived based on the erosion data obtained by testing the blade superalloy and coatings in a high-temperature erosion wind tunnel. The results show both the three-dimensional particle trajectories and the resulting blade impact locations for both uncoated and coated blade surfaces. In addition are shown the distribution of the erosion rate, impact frequency, impact velocity, and impact angle for the superalloy and the coating. The results indicate significant effects of the coating, especially on blade erosion and material deterioration.

Performance Estimation of Axial Flow Turbines

1970 ◽  
Vol 185 (1) ◽  
pp. 407-424 ◽  
Author(s):  
H. R. M. Craig ◽  
H. J. A. Cox
Keyword(s):  
Reynolds Number ◽  
Aspect Ratio ◽  
Gas Turbines ◽  
Three Dimensional ◽  
Axial Flow ◽  
Performance Estimation ◽  
Speed Ratio ◽  
Test Results ◽  
Wide Range ◽  
Relevant Variables

A comprehensive method of estimating the performance of axial flow steam and gas turbines is presented, based on analysis of linear cascade tests on blading, on a number of turbine test results, and on air tests of model casings. The validity of the use of such data is briefly considered. Data are presented to allow performance estimation of actual machines over a wide range of Reynolds number, Mach number, aspect ratio and other relevant variables. The use of the method in connection with three-dimensional methods of flow estimation is considered, and data presented showing encouraging agreement between estimates and available test results. Finally ‘carpets’ are presented showing the trends in efficiencies that are attainable in turbines designed over a wide range of loading, axial velocity/blade speed ratio, Reynolds number and aspect ratio.

Excess Streamwise Vorticity and Its Role in Secondary Flow

1987 ◽  
Vol 201 (6) ◽  
pp. 413-420 ◽  
Author(s):  
P W James
Keyword(s):  
Secondary Flow ◽  
Gas Turbines ◽  
Three Dimensional ◽  
Point Of View ◽  
Streamwise Vorticity ◽  
Three Dimensional Flow ◽  
Approximate Methods ◽  
Blade Row ◽  
Flow Through ◽  
Loss Term

The purpose of this paper is, firstly, to show how the concept of excess secondary vorticity arises naturally from attempts to recover three-dimensional flow details lost in passage-averaging the equations governing the flow through gas turbines. An equation for the growth of excess streamwise vorticity is then derived. This equation, which allows for streamwise entropy gradients through a prescribed loss term, could be integrated numerically through a blade-row to provide the excess vorticity at the exit to a blade-row. The second part of the paper concentrates on the approximate methods of Smith (1) and Came and Marsh (2) for estimating this quantity and demonstrates their relationship to each other and to the concept of excess streamwise vorticity. Finally the relevance of the results to the design of blading for gas turbines, from the point of view of secondary flow, is discussed.

Experimental and Numerical Investigation of Stator Exit Flow Field of an Automotive Torque Converter

1996 ◽  
Vol 118 (4) ◽  
pp. 835-843 ◽  
Author(s):  
B. V. Marathe ◽  
B. Lakshminarayana ◽  
Y. Dong
Keyword(s):  
Flow Field ◽  
Secondary Flow ◽  
Numerical Investigation ◽  
Three Dimensional ◽  
Axial Flow ◽  
Torque Converter ◽  
Operating Conditions ◽  
Navier Stokes ◽  
Complex Flow ◽  
Rate Of Decay

The objective of this investigation is to understand the nature of the complex flow field inside each element of the torque converter through a systematic experimental and numerical investigation of the flow field. A miniature five-hole probe was used to acquire the data at the exit of the stator at several operating conditions. The flow field is found to be highly three dimensional with substantial flow deviations, and secondary flow at the exit of the stator. The secondary flow structure, caused by the upstream radial variation of the through flow, induces flow overturning near the core. Flow separation near the shell causes flow underturning in this region. The rate of decay of stator wake is found to be slower than that observed in the wakes of axial flow turbine nozzles. The flow predictions by a Navier–Stokes code are in good agreement with the pressure and the flow field measured at the exit of the stator at the design and the off-design conditions.

scholarly journals Experimental and Computational Study of the Unsteady Flow in a 1.5 Stage Axial Turbine With Emphasis on the Secondary Flow in the Second Stator

1998 ◽  
Author(s):  
Ralf E. Walraevens ◽  
Heinz E. Gallus ◽  
Alexander R. Jung ◽  
Jürgen F. Mayer ◽  
Heinz Stetter
Keyword(s):  
Unsteady Flow ◽  
Secondary Flow ◽  
Computational Study ◽  
Three Dimensional ◽  
Cross Flow ◽  
Axial Flow ◽  
Time Dependent ◽  
Flow Structures ◽  
Mean Flow ◽  
Dependent Flow

A study of the unsteady flow in an axial flow turbine stage with a second stator blade row is presented. The low aspect ratio blades give way to a highly three-dimensional flow which is dominated by secondary flow structures. Detailed steady and unsteady measurements throughout the machine and unsteady flow simulations which include all blade rows have been carried out. The presented results focus on the second stator flow. Secondary flow structures and their origins are identified and tracked on their way through the passage. The results of the time-dependent secondary velocity vectors as well as flow angles and Mach number distributions as perturbation from the time-mean flow field are shown in cross-flow sections and azimuthal cuts throughout the domain of the second stator. At each location the experimental and numerical results are compared and discussed. A good overall agreement in the time-dependent flow behaviour as well as in the secondary flow structures is stated.

scholarly journals Improved Particle Trajectory Calculations Through Turbomachinery Affected by Coal Ash Particles

1981 ◽  
Author(s):  
B. Beecher ◽  
W. Tabakoff ◽  
A. Hamed
Keyword(s):  
Flow Field ◽  
Gas Turbines ◽  
Three Dimensional ◽  
Coal Ash ◽  
Two Dimensional ◽  
Flow Properties ◽  
Trajectory Calculations ◽  
Blade Thickness ◽  
Spline Fitting ◽  
Numerical Grid

Trajectories of small coal ash particles encountered in coal-fired gas turbines are calculated with an improved computer analysis currently under development. The analysis uses an improved numerical grid and mathematical spline-fitting techniques to account for three-dimensional gradients in the flow field and blade geometry. The greater accuracy thus achieved in flow field definition improves the trajectory calculations over previous two-dimensional models by allowing the small particles to react to radial variations in the flow properties. A greater accuracy thus achieved in the geometry definition permits particle rebounding in a direction perpendicular to the blade and flow path surfaces rather than in a two-dimensional plane. The improved method also accounts for radial variations in airfoil chord, stagger, and blade thickness when computing particle impact at a blade location.

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