Numerical Investigation of Ash Deposition on Nozzle Guide Vane Endwalls

2013 ◽  
Vol 135 (3) ◽  
Author(s):  
Brian P. Casaday ◽  
Ali A. Ameri ◽  
Jeffrey P. Bons
Keyword(s):  
Guide Vane ◽  
Leading Edge ◽  
Stokes Number ◽  
Secondary Flows ◽  
Ash Deposition ◽  
Deposition Rates ◽  
Nozzle Guide Vane ◽  
Turbine Vane ◽  
Tracking Model ◽  
Nozzle Guide

A computational study was performed to determine the factors that affect ash deposition rates on the endwalls in a nozzle guide vane passage. Deposition tests were simulated in flow around a flat plate with a cylindrical leading edge, as well as through a modern, high-performance turbine vane passage. The flow solution was first obtained independent of the presence of particulates, and individual ash particles were subsequently tracked using a Lagrangian tracking model. Two turbulence models were applied, and their differences were discussed. The critical viscosity model was used to determine particle deposition. Features that contribute to endwall deposition, such as secondary flows, turbulent dispersion, or ballistic trajectories, were discussed, and deposition was quantified. Particle sizes were varied to reflect Stokes numbers ranging from 0.01 to 1.0 to determine the effect on endwall deposition. Results showed that endwall deposition rates can be as high as deposition on the leading edge for particles with a Stokes number less than 0.1, but endwall deposition rates for a Stokes number of 1.0 were less than 25% of the deposition rates on the leading edge or pressure surface of the turbine vane. Deposition rates on endwalls were largest near the leading edge stagnation region on both the cylinder and vane geometries, with significant deposition rates downstream showing a strong correlation to the secondary flows.

Numerical Investigation of Ash Deposition on Nozzle Guide Vane Endwalls

2012 ◽  
Author(s):  
B. Casaday ◽  
A. Ameri ◽  
J. P. Bons
Keyword(s):  
Guide Vane ◽  
Leading Edge ◽  
Secondary Flows ◽  
Turbulent Dispersion ◽  
Ash Deposition ◽  
Deposition Rates ◽  
Nozzle Guide Vane ◽  
Turbine Vane ◽  
Tracking Model ◽  
Nozzle Guide

A computational study was performed to determine the factors that affect ash deposition rates on the endwalls in a nozzle guide vane passage. Deposition tests were simulated in flow around a flat plate with a cylindrical leading edge, as well as through a modern, high performance turbine vane passage. The flow solution was first obtained independent of the presence of particulates, and individual ash particles were subsequently tracked using a Langrangian tracking model. Two turbulence models were applied and their differences were discussed. The critical viscosity model was used to determine particle deposition. Features that contribute to endwall deposition, such as secondary flows, turbulent dispersion, or ballistic trajectories, were discussed and deposition was quantified. Particle sizes were varied, to reflect Stokes numbers ranging from 0.01 to 1.0, to determine the effect on endwall deposition. Results showed that endwall deposition rates can be as high as deposition on the leading edge for particles with a Stokes number less than 0.1, but endwall deposition rates for a Stokes numbers of 1.0 were less than 25% of the deposition rates on the leading edge or pressure surface of the turbine vane. Deposition rates on endwalls were largest near the leading edge stagnation region on both the cylinder and vane geometries, with significant deposition rates downstream showing a strong correlation to the secondary flows.

Influence of Pre-History and Leading Edge Contouring on Aero-Performance of a 3D Nozzle Guide Vane

2013 ◽  
Author(s):  
Ranjan Saha ◽  
Boris I. Mamaev ◽  
Jens Fridh ◽  
Björn Laumert ◽  
Torsten H. Fransson
Keyword(s):  
Guide Vane ◽  
Three Dimensional ◽  
Leading Edge ◽  
Stagnation Line ◽  
Wide Range ◽  
Nozzle Guide Vane ◽  
Turbine Vane ◽  
Loss Coefficients ◽  
Exit Mach Number ◽  
Nozzle Guide

Experiments are conducted to investigate the effect of the pre-history in the aerodynamic performance of a three-dimensional nozzle guide vane with a hub leading edge contouring. The performance is determined with two pneumatic probes (5 hole and 3 hole) concentrating mainly on the endwall. The investigated vane is a geometrically similar gas turbine vane for the first stage with a reference exit Mach number of 0.9. Results are compared for the baseline and filleted cases for a wide range of operating exit Mach numbers from 0.5 to 0.9. The presented data includes loading distributions, loss distributions, fields of exit flow angles, velocity vector and vorticity contour, as well as, mass-averaged loss coefficients. The results show an insignificant influence of the leading edge fillet on the performance of the vane. However, the pre-history (inlet condition) affects significantly in the secondary loss. Additionally, an oil visualization technique yields information about the streamlines on the solid vane surface which allows identifying the locations of secondary flow vortices, stagnation line and saddle point.

Aero-Thermal Aspects of Film Cooled Nozzle Guide Vane Endwalls: Part 1 — Aerodynamics

2020 ◽  
Author(s):  
Mahmood H. Alqefl ◽  
Kedar P. Nawathe ◽  
Pingting Chen ◽  
Rui Zhu ◽  
Yong W. Kim ◽  
...  
Keyword(s):  
Film Cooling ◽  
Guide Vane ◽  
Three Dimensional ◽  
Leading Edge ◽  
Secondary Flows ◽  
Protective Film ◽  
Cooling Flows ◽  
Nozzle Guide Vane ◽  
Nozzle Guide ◽  
Endwall Film Cooling

Abstract The first stage turbine of a modern gas turbine is subjected to high thermal loads which lead to a need for aggressive cooling schemes to protect its components from melting. Endwalls are particularly challenging to cool due to the complex system of secondary flows near them that wash the protective film coolants into the mainstream. This paper shows that without including combustor cooling, the complex secondary flow physics are not representative of modern engines. Aggressive injection of all cooling flows upstream of the passage is expected to interact and change passage aerodynamics and, subsequently, mixing and transport of coolants. This study describes, experimentally, the aero-thermal interaction of cooling flows near the endwall of a first stage nozzle guide vane passage. The test section involves an engine-representative combustor-turbine interface geometry, combustor coolant flow and endwall film cooling flow injected upstream of a linear cascade. The approach flow conditions represent flow exiting a cooled, low-NOx combustor. This first part of this two-part study aims to understand the complex aerodynamics near the endwall through detailed measurements of passage three-dimensional velocity fields with and without endwall film cooling. The aerodynamic measurements reveal a dominant vortex in the passage, named here as the Impingement Vortex, that opposes the passage vortex formed at the airfoil leading edge plane. This Impingement Vortex completely changes our description of flow over a modern film cooled endwall.

Aero-thermal Aspects of Film Cooled Nozzle Guide Vane Endwall - Part 1: Aerodynamics

2021 ◽  
pp. 1-54
Author(s):  
Mahmood H. Alqefl ◽  
Kedar P. Nawathe ◽  
Pingting Chen ◽  
Rui Zhu ◽  
Yong W. Kim ◽  
...  
Keyword(s):  
Film Cooling ◽  
Guide Vane ◽  
Three Dimensional ◽  
Leading Edge ◽  
Secondary Flows ◽  
Protective Film ◽  
Cooling Flows ◽  
Nozzle Guide Vane ◽  
Nozzle Guide ◽  
Endwall Film Cooling

Abstract The first stage turbine of a modern gas turbine is subjected to high thermal loads which lead to a need for aggressive cooling schemes to protect its components from melting. Endwalls are particularly challenging to cool due to the complex system of secondary flows near them that wash the protective film coolants into the mainstream. This paper shows that without including combustor cooling, the complex secondary flow physics are not representative of modern engines. Aggressive injection of all cooling flows upstream of the passage is expected to interact and change passage aerodynamics and, subsequently, mixing and transport of coolants. This study describes, experimentally, the aero-thermal interaction of cooling flows near the endwall of a first stage nozzle guide vane passage. The test section involves an engine-representative combustor-turbine interface geometry, combustor coolant flow and endwall film cooling flow injected upstream of a linear cascade. The approach flow conditions represent flow exiting a cooled, low-NOx combustor. This first part of this two-part study aims to understand the complex aerodynamics near the endwall through detailed measurements of passage three-dimensional velocity fields with and without endwall film cooling. The aerodynamic measurements reveal a dominant vortex in the passage, named here as the Impingement Vortex, that opposes the passage vortex formed at the airfoil leading edge plane. This Impingement Vortex completely changes our description of flow over a modern film cooled endwall.

Deposition on a Cooled Nozzle Guide Vane With Non-Uniform Inlet Temperatures

2015 ◽  
Author(s):  
Robin Prenter ◽  
Ali Ameri ◽  
Jeffrey P. Bons
Keyword(s):  
Film Cooling ◽  
Guide Vane ◽  
Internal Flow ◽  
Inlet Temperature ◽  
Temperature Profiles ◽  
Deposition Rates ◽  
Nozzle Guide Vane ◽  
Tracking Model ◽  
Nozzle Guide ◽  
Hot Streak

External deposition on a slot film cooled nozzle guide vane, subjected to non-uniform inlet temperatures, was investigated experimentally and computationally. Experiments were conducted using a four-vane cascade, operating at temperatures up to 1353 K and inlet Mach number of approximately 0.1. Surveys of temperature at the inlet and exit planes were acquired to characterize the form and migration of the hot streak. Film cooling was achieved on one of the vanes using a single span-wise slot. Deposition was produced by injecting sub-bituminous ash particles with a median diameter of 6.48μm upstream of the vane passage. Several deposition tests were conducted, including a baseline case, a hot streak only case, and a hot streak and film cooled case. Results indicate that capture efficiency is strongly related to both the inlet temperature profiles and film cooling. Deposit distribution patterns are also affected by changes in vane surface temperatures. A computational model was developed to simulate the external and internal flow, conjugate heat transfer, and deposition. Temperature profiles measured experimentally at the inlet were applied as thermal boundary conditions to the simulation. For deposition modeling, an Eulerian-Lagrangian particle tracking model was utilized to track the ash particles through the flow. An experimentally tuned version of the critical viscosity sticking model was implemented, with predicted deposition rates matching experimental results well. Comparing overall deposition rates to results from previous studies indicate that the combined effect of non-uniform inlet temperatures and film cooling cannot be accurately simulated by simple superposition of the two independent effects, thus inclusion of both conditions in experiments is necessary for realistic simulation of external deposition.

Deposition on a Cooled Nozzle Guide Vane With Nonuniform Inlet Temperatures

2016 ◽  
Vol 138 (10) ◽  
Author(s):  
Robin Prenter ◽  
Ali Ameri ◽  
Jeffrey P. Bons
Keyword(s):  
Film Cooling ◽  
Guide Vane ◽  
Internal Flow ◽  
Inlet Temperature ◽  
Temperature Profiles ◽  
Deposition Rates ◽  
Nozzle Guide Vane ◽  
Tracking Model ◽  
Nozzle Guide ◽  
Hot Streak

External deposition on a slot film cooled nozzle guide vane, subjected to nonuniform inlet temperatures, was investigated experimentally and computationally. Experiments were conducted using a four-vane cascade, operating at temperatures up to 1353 K and inlet Mach number of approximately 0.1. Surveys of temperature at the inlet and exit planes were acquired to characterize the form and migration of the hot streak. Film cooling was achieved on one of the vanes using a single spanwise slot. Deposition was produced by injecting sub-bituminous ash particles with a median diameter of 6.48 μm upstream of the vane passage. Several deposition tests were conducted, including a baseline case, a hot streak-only case, and a hot streak and film cooled case. Results indicate that capture efficiency is strongly related to both the inlet temperature profiles and film cooling. Deposit distribution patterns are also affected by changes in vane surface temperatures. A computational model was developed to simulate the external and internal flow, conjugate heat transfer, and deposition. Temperature profiles measured experimentally at the inlet were applied as thermal boundary conditions to the simulation. For deposition modeling, an Eulerian–Lagrangian particle tracking model was utilized to track the ash particles through the flow. An experimentally tuned version of the critical viscosity sticking model was implemented, with predicted deposition rates matching experimental results well. Comparing overall deposition rates to results from previous studies indicates that the combined effect of nonuniform inlet temperatures and film cooling cannot be accurately simulated by simple superposition of the two independent effects; thus, inclusion of both conditions in experiments is necessary for realistic simulation of external deposition.

Film Cooling Experiments With Flow Introduced Upstream of a First Stage Nozzle Guide Vane Through Slots of Various Geometries

2002 ◽  
Author(s):  
Rohit A. Oke ◽  
Terrence W. Simon
Keyword(s):  
Film Cooling ◽  
Guide Vane ◽  
Leading Edge ◽  
Suction Side ◽  
Main Flow ◽  
Secondary Flows ◽  
Base Line ◽  
Cooling Flow ◽  
Nozzle Guide Vane ◽  
Nozzle Guide

This paper describes the advantages of introducing film cooling flow through the endwall upstream of the first stage nozzle guide vane. To perform these studies, a linear cascade is built. It consists of three vanes and two endwalls that form two passages. One endwall is flat and the other is contoured from upstream of the leading edge, continuing through the passage. The approach flow is of high turbulence and large length scale, representative of the engine combustor exit flow. Film cooling flow is introduced through two successive rows of slots, a single row of slots and slots that have particular area distributions in the pitchwise direction. Measurements are taken by heating the film cooling flow slightly above the main flow temperature and recording temperature distributions in the film cooling flow-main flow mixing zone at various axial planes. The single and double slot injection cases represent base-line injection geometries. They show that at lower ratios of coolant to main flow momentum fluxes, film cooling flow migrates toward the suction side due to secondary flow. At higher ratios, the pressure side endwall region is cooled more effectively. Observations are drawn by comparing the baseline injection cases with cases of different geometries for which slots are blocked partially to re-distribute mass and momentum injection rates of the emerging flow. The downstream evolutions of temperature contours are discussed. The idea is to utilize secondary flows to control pitchwise coolant distributions.

Numerical Analysis on Effects of the Contoured Endwall on the Three Dimensional Flow Characteristics in an Annular Turbine Nozzle Vane

2007 ◽  
Author(s):  
Wu Sang Lee ◽  
Jin Taek Chung ◽  
Dae Hyun Kim ◽  
Seung Joo Choe
Keyword(s):  
Guide Vane ◽  
Three Dimensional ◽  
Flow Characteristics ◽  
Cross Flow ◽  
Leading Edge ◽  
Secondary Flows ◽  
Three Dimensional Flow ◽  
Dimensional Flow ◽  
Nozzle Guide Vane ◽  
Nozzle Guide

The three-dimensional flow in a turbine nozzle guide vane passage causes large secondary loss through the passage and increased heat transfer on the blade surface. In order to reduce or control these secondary flows, a linear turbine with contoured endwall configurations was used and changes in the three-dimensional flow field were analyzed and discussed. Contoured endwalls are installed at a location downstream of the saddle point near the leading edge of the pressure side blade and several positions along the centerline of the passage at constant distance. The objective of this study is to document the development of the three-dimensional flow in a turbine nozzle guide vane cascade with modified endwall. In addition, it proposes and appropriates endwall contouring which shows best overall loss reduction performance among the simulated contoured endwall. The results of this study show that the development of passage vortex and cross flow in the cascade composed of one flat and one contoured endwalls are affected by the acceleration which occurs in contoured endwall side. The overall loss is reduced near the flat endwall rather than contoured endwall, the best performance was shown for the case of 10–15% contoured for span-wise, 40–70% length of chord from trailing edge.

Effects of Endwall Film Coolant Flow Rate on Secondary Flows and Coolant Mixing in a First Stage Nozzle Guide Vane

2021 ◽  
Author(s):  
Mahmood Alqefl ◽  
Kedar Nawathe ◽  
Pingting Chen ◽  
Rui Zhu ◽  
Yong Kim ◽  
...  
Keyword(s):  
Flow Rate ◽  
Guide Vane ◽  
Secondary Flows ◽  
Coolant Flow ◽  
Coolant Flow Rate ◽  
Nozzle Guide Vane ◽  
Nozzle Guide

Aerothermal Performance of Shielded Vane Design

2017 ◽  
Vol 139 (11) ◽  
Author(s):  
Ioanna Aslanidou ◽  
Budimir Rosic
Keyword(s):  
Heat Transfer ◽  
Total Pressure ◽  
High Speed ◽  
Guide Vane ◽  
Leading Edge ◽  
Experimental Facility ◽  
Numerical Studies ◽  
Nozzle Guide Vane ◽  
Inlet Conditions ◽  
Nozzle Guide

This paper presents an experimental investigation of the concept of using the combustor transition duct wall to shield the nozzle guide vane leading edge. The new vane is tested in a high-speed experimental facility, demonstrating the improved aerodynamic and thermal performance of the shielded vane. The new design is shown to have a lower average total pressure loss than the original vane, and the heat transfer on the vane surface is overall reduced. The peak heat transfer on the vane leading edge–endwall junction is moved further upstream, to a region that can be effectively cooled as shown in previously published numerical studies. Experimental results under engine-representative inlet conditions showed that the better performance of the shielded vane is maintained under a variety of inlet conditions.

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