Full-Scale Vibration Testing of Nozzle Guide Vanes

2021 ◽  
Author(s):  
Giuseppe Macoretta ◽  
Bernardo Disma Monelli ◽  
Paolo Neri ◽  
Federico Bucciarelli ◽  
Damaso Checcacci ◽  
...  
Keyword(s):  
Thermal Loading ◽  
Guide Vane ◽  
Full Scale ◽  
Operational Flexibility ◽  
Additional Control ◽  
Partial Load ◽  
Nozzle Guide Vane ◽  
Stator Vane ◽  
Nozzle Guide ◽  
Nozzle Guide Vanes

Abstract An increasing number of turboexpanders are equipped with Nozzle Guide Vane (NGV) as the first stator stage. By varying the throat area of the first stator vane the NGV enables an additional control methodology to the line-up power output allowing higher operational flexibility and higher efficiency at partial load and partial speed. The design of this component might become critical for enabling high expander availability considering its exposure to high temperature, thermal loading, and fluid induced vibrations. This is especially true also considering that the vibration frequencies of this sub-assembly are influenced by internal clearances and by the value of the friction coefficient, which leaves a relevant margin of error when using numerical methods (such as FEM) for predicting the actual structural behavior of this component. In this paper, the design of a full-scale test bench for the determination of both friction coefficients and modal behavior of a nozzle guide vane geometry is described. The bench enables us to simulate the pre-load due to aerodynamic forces on the NGV airfoil simulating the actual working conditions of bushes and bearings.

scholarly journals Secondary Flow Reduction in a Nozzle Guide Vane Cascade by Non-Axisymmetric End-Wall Profiling

1999 ◽  
Author(s):  
J. Yan ◽  
D. G. Gregory-Smith ◽  
P. J. Walker
Keyword(s):  
Secondary Flow ◽  
Static Pressure ◽  
Guide Vane ◽  
Suction Surface ◽  
Linear Cascade ◽  
Pressure Surface ◽  
Nozzle Guide Vane ◽  
Nozzle Guide ◽  
Nozzle Guide Vanes ◽  
End Wall

A linear cascade of HP steam turbine nozzle guide vanes was designed and built in order to study the effect of a non-axisymmetric profile for the endwall. The profile was designed by using CFD for the purpose of reducing the secondary flow. The method was to use convex curvature near the pressure surface to reduce the static pressure and concave curvature near the suction surface to increase it. Thus the cross passage pressure gradient which drives the secondary flow would be reduced. Detailed investigations of the flow field with a flat end-wall and the profiled end-wall were conducted. The effect of the profiled end-wall on the secondary flow development was determined and also compared with the CFD design predictions. It was found that the secondary loss and secondary kinetic energy were both reduced by about 20% with the shaped endwall, and a more uniform exit flow was also achieved.

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

2021 ◽  
Vol 143 (3) ◽  
Author(s):  
Mahmood H. Alqefl ◽  
Kedar P. Nawathe ◽  
Pingting Chen ◽  
Rui Zhu ◽  
Yong W. Kim ◽  
...  
Keyword(s):  
Test Section ◽  
Film Cooling ◽  
Gas Turbines ◽  
Thermal Loading ◽  
Guide Vane ◽  
Secondary Flows ◽  
Cooling Flows ◽  
Nozzle Guide Vane ◽  
Nozzle Guide ◽  
Endwall Film Cooling

Abstract Modern gas turbines are subjected to very high thermal loading. This leads to a need for aggressive cooling to protect components from damage. Endwalls are particularly challenging to cool due to a complex system of secondary flows near them that wash and disrupt the protective coolant films. This highly three-dimensional flow not only affects but is also affected by the momentum of film cooling flows, whether injected just upstream of the passage to intentionally cool the endwall or as combustor cooling flows injected further upstream in the engine. This complex interaction between the different cooling flows and passage aerodynamics has been recently studied in a first stage nozzle guide vane. The present paper presents a detailed study on the sensitivity of aero-thermal interactions to endwall film cooling mass flow to mainstream flow ratio. The test section represents a first stage nozzle guide vane with a contoured endwall and endwall film cooling injected just upstream of it. The test section also includes an engine-representative combustor–turbine interface geometry with combustor cooling flows injected at a constant rate. The approach flow conditions represent flow exiting a low-NOx combustor. Adiabatic surface thermal measurements and in-passage velocity and thermal field measurements are presented and discussed. The results show the dynamics of passage vortex suppression and the increase of impingement vortex strength as MFR changes. The effects of these changes of secondary flows on coolant distribution are presented.

scholarly journals Efficiency Measurements of an Annular Nozzle Guide Vane Cascade With Different Film Cooling Geometries

1998 ◽  
Author(s):  
Charles R. B. Day ◽  
Martin L. G. Oldfield ◽  
Gary D. Lock ◽  
Stephen N. Dancer
Keyword(s):  
Film Cooling ◽  
Total Pressure ◽  
Guide Vane ◽  
Cumulative Effect ◽  
Aerodynamic Efficiency ◽  
Nozzle Guide Vane ◽  
Density Ratios ◽  
Nozzle Guide ◽  
Annular Cascade ◽  
Nozzle Guide Vanes

This paper further extends the research reported by Day et al. (1997), which reported aerodynamic efficiency measurements on an annular cascade of engine representative transonic nozzle guide vanes with extensive film cooling. This work compares the measured aerodynamic efficiencies of blades with 14 rows of cylindrical cooling holes with a new geometry in which 8 of the rows have been replaced by holes having a fan-shaped exit geometry. The effects of adding trailing edge slot ejection are also presented. By selectively blocking rows of holes, the cumulative effect on the mid-span efficiency of adding rows of cooling holes has also been determined. A dense foreign gas (SF6/Ar mixture) is used to simulate engine representative coolant-to-mainstream density ratios, momentum ratios and blowing rates under ambient temperature conditions. The flowfield measurements have been obtained using a four-hole pyramid probe in a short duration blowdown facility which correctly models engine Reynolds and Mach numbers, as well as the inlet turbulence intensity. Experimental results are presented as area traverse maps (total pressure, isentropic Mach number and flow angles), from which the incremental changes in efficiency due to film cooling have been calculated. The effects of different assumptions for the coolant total pressure are shown. Experimental data agrees reasonably well with loss predictions using a Hartsel model.

Experimental Evaluation of Service-Exposed Nozzle Guide Vane Damage in a Rolls Royce A-250 Gas Turbine

2013 ◽  
Author(s):  
D. Bouchard ◽  
A. Asghar ◽  
M. LaViolette ◽  
W. D. E. Allan ◽  
R. Woodason
Keyword(s):  
Performance Metrics ◽  
Guide Vane ◽  
Trailing Edge ◽  
Root Area ◽  
Trailing Edges ◽  
Nozzle Guide Vane ◽  
Nozzle Guide ◽  
Edge Damage ◽  
Annular Cascade ◽  
Nozzle Guide Vanes

A unique methodology and test rig was designed to evaluate the degradation of damaged Nozzle Guide Vanes in a transonic annular cascade in the short duration facility at the Royal Military College. A custom test section was designed which featured a novel rotating instrumentation suite. This permitted 360° multi-span traverse measurements downstream of unmodified turbine NGV rings from a Rolls-Royce/Allison A-250 turbo-shaft engine. Downstream total pressure was measured at four span-wise locations on both an undamaged reference and a damaged test article. Three performance metrics were developed in an effort to determine characteristic signatures for common operational damage such as trailing edge bends or cracked trailing edges. The highest average losses were observed in the root area, while the lowest occurred closer to the NGV tips. The results from this study indicated that multiple span-wise traverses were required to detect localized trailing edge damage. Recommendations have been made for future tests, for test rigs and for ideas to develop performance metrics.

Nozzle Guide Vane Shock Wave Propagation and Bifurcation in a Transonic Turbine Rotor

1990 ◽  
Author(s):  
A. B. Johnson ◽  
M. L. G. Oldfield ◽  
M. J. Rigby ◽  
M. B. Giles
Keyword(s):  
Shock Wave ◽  
Thermal Loading ◽  
Guide Vane ◽  
Leading Edge ◽  
Turbine Rotor ◽  
Incoming Wave ◽  
Pressure Surface ◽  
Nozzle Guide Vane ◽  
Transonic Turbine ◽  
Nozzle Guide

A study of the propagation of a Nozzle Guide Vane (NGV) trailing edge shock wave through a transonic turbine rotor passage is presented. The work was based on experimental tests carried out in the Isentropic Light Piston Tunnel in Oxford University using a rotating bar NGV shock wave simulator, together with schlieren photography and wide band width surface pressure and heat transfer rate measurements. The study identifies a previously unexplained interaction between the incoming wave and the rotor leading edge, which causes the nucleation of a Vortical Bubble. This bubble has been shown to enhance the thermal loading on the early pressure surface of the blade. A method of controlling this bubble and heat loading is also considered. A previously unseen “Lambda” interaction between the shock wave and the rotor pressure surface is also identified.

Temperature Effects on Nozzle Guide Vane Deposition in a New Turbine Cascade Rig

2016 ◽  
Author(s):  
Ryan Lundgreen ◽  
Craig Sacco ◽  
Robin Prenter ◽  
Jeffrey P. Bons
Keyword(s):  
Guide Vane ◽  
Turbine Engines ◽  
Turbine Cascade ◽  
Stagnation Line ◽  
Pressure Surface ◽  
Nozzle Guide Vane ◽  
First Results ◽  
Inlet Conditions ◽  
Nozzle Guide ◽  
Nozzle Guide Vanes

A new turbine cascade has been constructed that is designed to investigate the performance of actual nozzle guide vane hardware at temperatures representative of modern gas turbine engines. The facility is designed to investigate internal and external deposition, analyze the effectiveness of new cooling techniques, characterize material systems such as metal substrates or coatings, and assess the aerodynamic performance of a vane. The results presented here are the first results obtained in this new facility. External deposition on cooled CFM56 nozzle guide vanes has been explored at inlet temperatures of 1090° C, 1265° C, and 1350° C. Results at 1090° C have been compared to similar results in a previous facility. External deposition tests at temperatures greater than 1100° C on actual turbine hardware have not been reported publicly prior to this paper. These results show that deposition is concentrated at the stagnation line at all three inlet conditions. The amount of deposition on the vane pressure surface increased with increasing inlet temperatures.

Experimental Evaluation of Service-Exposed Nozzle Guide Vane Damage in a Rolls Royce A-250 Gas Turbine

2014 ◽  
Vol 136 (10) ◽  
Author(s):  
D. Bouchard ◽  
A. Asghar ◽  
M. LaViolette ◽  
W. D. E. Allan ◽  
R. Woodason
Keyword(s):  
Performance Metrics ◽  
Guide Vane ◽  
Trailing Edge ◽  
Root Area ◽  
Trailing Edges ◽  
Nozzle Guide Vane ◽  
Nozzle Guide ◽  
Edge Damage ◽  
Annular Cascade ◽  
Nozzle Guide Vanes

A unique methodology and test rig was designed to evaluate the degradation of damaged nozzle guide vanes (NGVs) in a transonic annular cascade in the short duration facility at the Royal Military College. A custom test section was designed which featured a novel rotating instrumentation suite. This permitted 360 deg multispan traverse measurements downstream from unmodified turbine NGV rings from a Rolls-Royce/Allison A-250 turbo-shaft engine. The downstream total pressure was measured at four spanwise locations on both an undamaged reference and a damaged test article. Three performance metrics were developed in an effort to determine characteristic signatures for common operational damage such as trailing edge bends or cracked trailing edges. The highest average losses were observed in the root area, while the lowest occurred closer to the NGV tips. The results from this study indicated that multiple spanwise traverses were required to detect localized trailing edge damage. Recommendations are made for future testing and to further develop performance metrics.

Contoured Endwall Flow and Heat Transfer Experiments With Combustor Coolant and Gap Leakage Flows for a Turbine Nozzle Guide Vane

2016 ◽  
Author(s):  
Reema Saxena ◽  
Mahmood H. Alqefl ◽  
Zhao Liu ◽  
Hee-Koo Moon ◽  
Luzeng Zhang ◽  
...  
Keyword(s):  
High Pressure ◽  
Gas Turbine ◽  
Mass Flow ◽  
Film Cooling ◽  
Thermal Loading ◽  
Guide Vane ◽  
Nozzle Guide Vane ◽  
Adiabatic Effectiveness ◽  
Interfacial Gap ◽  
Nozzle Guide

Flow in a high pressure gas turbine passage is complex, involving systems of secondary vortex flows and strong transverse pressure gradients. This complexity causes difficulty in providing film cooling coverage to the hub endwall region, which is subjected to high thermal loading due to combustor exit hot core gases. Therefore, an improved understanding of these flow features and their effects on endwall film cooling is needed to assist designers in developing efficient cooling schemes. The experimental study presented in this paper is performed on a linear, stationary, two-passage cascade representing the first stage nozzle guide vane of a high-pressure gas turbine. The sources of film cooling flows are the upstream combustor liner coolant and the leakage flow from the combustor-nozzle guide vane interfacial gap. Measurements are performed on an axisymmetrically-contoured endwall passage under conditions of various leakage mass flow rates to mainstream flow ratios (MFR= 0.5%, 1.0%, 1.5%). Flow migration and mixing are documented by measuring passage thermal fields and adiabatic effectiveness values over the endwall. It is found that, compared to our previous studies with a rotor inlet leakage slot geometry, the thin slot geometry of the nozzle leakage path gives a more uniform coolant spread over the endwall with significant coverage reaching the downstream and pressure-side regions of the passage. Interestingly, the coverage is seen to be only weakly dependent on the leakage mass low ratio and even reduce slightly with an increase in mass flow ratio above 1%, as indicated by lowered endwall adiabatic effectiveness values.

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

2020 ◽  
Author(s):  
Mahmood H. Alqefl ◽  
Kedar P. Nawathe ◽  
Pingting Chen ◽  
Rui Zhu ◽  
Yong W. Kim ◽  
...  
Keyword(s):  
Test Section ◽  
Film Cooling ◽  
Gas Turbines ◽  
Thermal Loading ◽  
Guide Vane ◽  
Secondary Flows ◽  
Cooling Flows ◽  
Nozzle Guide Vane ◽  
Nozzle Guide ◽  
Endwall Film Cooling

Abstract Modern gas turbines are subjected to very high thermal loading. This leads to a need for aggressive cooling to protect components from damage. Endwalls are particularly challenging to cool due to a complex system of secondary flows near them that wash and disrupt the protective coolant films. This highly three-dimensional flow not only affects but is also affected by the momentum of film cooling flows, whether injected just upstream of the passage to intentionally cool the endwall, or as combustor cooling flows injected further upstream in the engine. This complex interaction between the different cooling flows and passage aerodynamics has been recently studied in a first stage nozzle guide vane. The present paper presents a detailed study on the sensitivity of aero-thermal interactions to endwall film cooling MFR (cooling mass flow to mainstream flow ratio). The test section represents a first stage nozzle guide vane with a contoured endwall and endwall film cooling injected just upstream of it. The test section also includes an engine-representative combustor-turbine interface geometry with combustor cooling flows injected at a constant rate. The approach flow conditions represent flow exiting a low-NOx combustor. Adiabatic surface thermal measurements and in-passage velocity and thermal field measurements are presented and discussed. The results show the dynamics of passage vortex suppression and the increase of impingement vortex strength as MFR changes. The effects of these changes of secondary flows on coolant distribution are presented.

Influence of Upstream Flow Conditions on the Heat Transfer to Nozzle Guide Vanes

1988 ◽  
Vol 110 (3) ◽  
pp. 412-416 ◽  
Author(s):  
V. Krishnamoorthy ◽  
B. R. Pai ◽  
S. P. Sukhatme
Keyword(s):  
Guide Vane ◽  
Gas Temperature ◽  
Flow Conditions ◽  
Cold Flow ◽  
Hot Gas ◽  
Nozzle Guide Vane ◽  
High Turbulence ◽  
Nozzle Guide ◽  
Nozzle Guide Vanes ◽  
Upstream Flow

The influence of a combustor located just upstream of a nozzle guide vane cascade on the heat flux distribution to the nozzle guide vane was experimentally investigated. The surface temperature distribution around the convectively cooled vane of the cascade was obtained by locating the cascade, firstly in a low-turbulence uniform hot gas stream, secondly in a high-turbulence, uniform hot gas stream, and thirdly in a high-turbulence, nonuniform hot gas stream present just downstream of the combustor exit. The results indicate that the increased blade surface temperatures observed for the cascade placed just downstream of the combustor can be accounted for by the prevailing turbulence level measured at cascade inlet in cold-flow conditions and the average gas temperature at the cascade inlet.

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