Effect of Incidence Angle on Gas Turbine First-Stage Nozzle Guide Vane Leading Edge and Gill Region Film Cooling

2012 ◽  
Author(s):  
Yang Zhang ◽  
Xin Yuan
Keyword(s):  
Film Cooling ◽  
Incidence Angle ◽  
Leading Edge ◽  
Inlet Flow ◽  
Flow Angle ◽  
Cooling Performance ◽  
Guide Vanes ◽  
Nozzle Guide ◽  
Nozzle Guide Vanes ◽  
Compound Angle

The nonuniformity of the Hp turbine inlet flow field put forward higher requirements for NGV (Nozzle Guide Vanes) leading edge and gill region film cooling. The assumption of design condition in most of the experiments couldn’t reflect the true operation environment in the Hp turbine NGV. The factor of off-design condition was incorporated into the experiment in this research. The GE-E3 Hp turbine nozzle guide vanes were used in the experiment to investigate the cooling performance of injection from leading edge and gill region with inlet Reynolds numbers of Re = 3.5×105 and inlet Mach number of Ma = 0.1. The compound angle fan-shaped film cooling hole configuration was applied. The cooling characteristics at off-design condition were analyzed and compared in the paper. The leading edge and gill region film cooling performance was assessed with the incidence angle varying from i = −10deg to i = +10deg. The blowing ratio varying from M = 0.7 to M = 1.3, was also selected as an experimental variable. Film cooling effectiveness distribution was measured using PSP (Pressure Sensitive Paint) technique. The film cooling performance of the compound angle fan-shaped holes was assessed at both design and off-design conditions. The object of this research is to change the concept that NGV leading edge film cooling experiment only needs the data at design condition. Through the comparative analysis of experimental results at different inlet flow angle, the influence of off-design condition on NGV leading edge and gill region film cooling could be illustrated at a reasonable level.

Degradation of Aerodynamic Performance of an Intermediate-Pressure Steam Turbine Due to Erosion of Nozzle Guide Vanes and Rotor Blades

2018 ◽  
Vol 141 (1) ◽  
Author(s):  
Koichi Yonezawa ◽  
Tomoki Kagayama ◽  
Masahiro Takayasu ◽  
Genki Nakai ◽  
Kazuyasu Sugiyama ◽  
...  
Keyword(s):  
Numerical Simulations ◽  
Steam Turbine ◽  
Rotor Blade ◽  
Rotor Blades ◽  
Flow Angle ◽  
Guide Vanes ◽  
Intermediate Pressure ◽  
Pressure Steam ◽  
Nozzle Guide ◽  
Nozzle Guide Vanes

Deteriorations of nozzle guide vanes (NGVs) and rotor blades of a steam turbine through a long-time operation usually decrease a thermal efficiency and a power output of the turbine. In this study, influences of blade deformations due to erosion are discussed. Experiments were carried out in order to validate numerical simulations using a commercial software ANSYS-cfx. The numerical results showed acceptable agreements with experimental results. Variation of flow characteristics in the first stage of the intermediate pressure steam turbine is examined using numerical simulations. Geometries of the NGVs and the rotor blades are measured using a 3D scanner during an overhaul. The old NGVs and the rotor blades, which were used in operation, were eroded through the operation. The erosion of the NGVs leaded to increase of the throat area of the nozzle. The numerical results showed that rotor inlet velocity through the old NGVs became smaller and the flow angle of attack to the rotor blade leading edge became smaller. Consequently, the rotor power decreased significantly. Influences of the flow angle of at the rotor inlet were examined by parametric calculations and results showed that the angle of attack was an important parameter to determine the rotor performance. In addition, the influence of the deformation of the rotor blade was examined. The results showed that the degradation of the rotor performance decreased in accordance with the decrease of blade surface area.

Numerical Investigation of the Effect of Inlet Flow Angle on Film Cooling Performance for the Blade Tip With Suction Surface Squealer Rim

2019 ◽  
Author(s):  
Zhiqiang Yu ◽  
Jianjun Liu ◽  
Chen Li ◽  
Baitao An
Keyword(s):  
Mass Flow ◽  
Film Cooling ◽  
Incidence Angle ◽  
Leading Edge ◽  
Flow Ratio ◽  
Suction Surface ◽  
Cooling Performance ◽  
Tip Leakage ◽  
Pressure Surface ◽  
Mass Flow Ratio

Abstract Numerical investigations have been performed to study the effect of incidence angle on the aerodynamic and film cooling performance for the suction surface squealer tip with different film-hole arrangements at τ = 1.5% and BR = 1.0. Meanwhile, the full squealer tip as baseline is also investigated. Three incidence angles at design condition (0 deg) and off-design conditions (± 7 deg) are investigated. The suction surface, pressure surface, and the camber line have seven holes each, with an extra hole right at the leading edge. The Mach number at the cascade inlet and outlet are 0.24 and 0.52, respectively. The results show that the incidence angle has a significant effect on the tip leakage flow characteristics and coolant flow direction. The film cooling effectiveness distribution is altered, especially for the film holes near the leading edge. When the incidence angle changes from +7 deg to 0 and −7 deg, the ‘re-attachment line’ moves downstream and the total tip leakage mass flow ratio decreases, but the suction surface tip leakage mass flow ratio near leading edge increases. In general, the total tip leakage mass flow ratio for suction surface squealer tip is 1% greater than that for full squealer tip at the same incidence angle. The total pressure loss coefficient of suction surface squealer tip is larger than that for full squealer tip. The full squealer tip with film holes near suction surface and the suction surface squealer tip with film hole along camber line show high film cooling performance, and the area averaged film cooling effectiveness at positive incidence angle +7 deg is higher than that at 0 and −7 deg. The coolant discharged from film holes near pressure surface only cools narrow region near pressure surface.

Film Cooling Research on the Endwall of a Turbine Nozzle Guide Vane in a Short Duration Annular Cascade: Part 1—Experimental Technique and Results

1992 ◽  
Vol 114 (4) ◽  
pp. 734-740 ◽  
Author(s):  
S. P. Harasgama ◽  
C. D. Burton
Keyword(s):  
Heat Transfer ◽  
Film Cooling ◽  
Guide Vane ◽  
Density Ratio ◽  
Suction Side ◽  
Coolant Temperature ◽  
Guide Vanes ◽  
Nozzle Guide ◽  
Annular Cascade ◽  
Nozzle Guide Vanes

Heat transfer and aerodynamic measurements have been made on the endwalls of an annular cascade of turbine nozzle guide vanes in the presence of film cooling. The results indicate that high levels of cooling effectiveness can be achieved on the endwalls of turbine nozzle guide vanes (NGV). The NGV were operated at the correct engine nondimensional conditions of Reynolds number, Mach number, gas-to-wall temperature ratio, and gas-to-coolant density ratio. The results show that the secondary flow and horseshoe vortex act on the coolant, which is convected toward the suction side of the NG V endwall passage. Consequently the coolant does not quite reach the pressure side/casing trailing edge, leading to diminished cooling in this region. Increasing the blowing rate from 0.52 to 1.1 results in significant reductions in heat transfer to the endwall. Similar trends are evident when the coolant temperature is reduced. Measured heat transfer rates indicate that over most of the endwall region the film cooling reduces the Nusselt number by 50 to 75 percent.

Film Cooling Research on the Endwall of a Turbine Nozzle Guide Vane in a Short Duration Annular Cascade: Part 1 — Experimental Technique and Results

1991 ◽  
Author(s):  
S. P. Harasgama ◽  
C. D. Burton
Keyword(s):  
Heat Transfer ◽  
Film Cooling ◽  
Guide Vane ◽  
Density Ratio ◽  
Suction Side ◽  
Coolant Temperature ◽  
Guide Vanes ◽  
Nozzle Guide ◽  
Annular Cascade ◽  
Nozzle Guide Vanes

Heat transfer and aerodynamic measurements have been made on the endwalls of an annular cascade of turbine nozzle guide vanes in the presence of film cooling. The results indicate that high levels of cooling effectiveness can be achieved on the endwalls of turbine nozzle guide vanes (NGV). The NGV were operated at the correct engine non-dimensional conditions of Reynolds number, Mach number, gas-to-wall temperature ratio and gas-to-coolant density ratio. The results show that the secondary flow and horse-shoe vortex act on the coolant which is converted towards the suction side of the NGV endwall passage. Consequently the coolant does not quite reach the pressure side/casing trailing edge, leading to diminished cooling in this region. Increasing the blowing rate from 0.52 to 1.1 results in significant reductions in heat transfer to the endwall. Similar trends are evident when the coolant temperature is reduced. Measured heat transfer rates indicate that over most of the endwall region the film cooling reduces the Nusselt number by 50% to 75%.

scholarly journals Experimentally Measured Effects of Incidence Angle on the Adiabatic and Overall Effectiveness of a Fully Cooled Turbine Airfoil With Shaped Showerhead Holes

2017 ◽  
Vol 139 (9) ◽  
Author(s):  
Kyle Chavez ◽  
Thomas N. Slavens ◽  
David Bogard
Keyword(s):  
Incidence Angle ◽  
Density Ratio ◽  
Leading Edge ◽  
Inlet Flow ◽  
Flow Angle ◽  
Stagnation Line ◽  
Film Cooling Effectiveness ◽  
Adiabatic Effectiveness ◽  
Inlet Conditions ◽  
Overall Effectiveness

Manufacturing and assembly variation can lead to shifts in the inlet flow incidence angles of a rotating turbine airfoil row. Understanding the sensitivity of the adiabatic film cooling effectiveness to a range of inlet conditions is necessary to verify the robustness of a cooling design. In order to investigate the effects of inlet flow incidence angles, adiabatic and overall effectiveness data were measured in a low speed linear cascade at 0 deg and 10 deg of the designed operating condition. Tests were completed at an inlet Reynolds number of Re = 120,000 and a turbulence intensity of Tu = 5% at the leading edge of the test article. Particle image velocimetry was used to verify the incident flow angle for each angle studied. The test section was first adjusted so that the pressure distribution and stagnation line of the airfoil matched those predicted by an aerodynamic computational fluid dynamics (CFD) model. IR thermography was then used to measure the adiabatic effectiveness levels of the fully cooled airfoil model with nine rows of shaped holes of varying construction and feed delivery. Measurements were taken over a range of blowing ratios and at a density ratio of DR = 1.23. This process was repeated for the two incidence angles measured, while the inlet pressure to the airfoil model was held constant for these incidence angle changes. Differences in laterally adiabatic effectiveness across the airfoil model were most evident in the showerhead, with changes as large as 0.2. The effect persisted most strongly at s/D = ±35 downstream of the stagnation row of holes, but was visible over the whole viewable area of 160 s/D. The effect was due to the stagnation line affecting the film at the showerhead row. Due to this effect, the showerhead was investigated in detail, including the effects of the stagnation line shift as well as the influence of the incidence angle on the overall effectiveness of the showerhead region. It was found that the stagnation line has the tendency to dramatically increase the near-hole adiabatic effectiveness levels when positioned within the breakout footprint of the hole. The effect persisted for the overall effectiveness study, since the hole spacing for this particular configuration was wide enough that the through hole convection was not completely dominant. This is the first study to present measured effectiveness values over both the pressure- and suction-side surfaces of a fully cooled airfoil for appreciably off-nominal incidence angles as well as examine adiabatic and overall effectiveness levels for a conical stagnation row of holes.

scholarly journals Effect of Inlet Flow Angle on the Erosion of Radial Turbine Guide Vanes

1989 ◽  
Author(s):  
Hasan Eroglu ◽  
Widen Tabakoff
Keyword(s):  
Particle Size ◽  
Incidence Angle ◽  
Particle Dynamics ◽  
Particulate Flow ◽  
Inlet Flow ◽  
Flow Angle ◽  
Guide Vanes ◽  
Radial Turbine ◽  
The Impact ◽  
Radial Turbines

The results of an investigation of the particle dynamics and the blade erosion at the impact locations in radial turbine guide vanes are presented. The attention is focused in particular on the effect of inlet flow angle on the erosion of the blades, since the flow entering the guide vanes usually has an incidence angle due to the upstream scroll geometry. The total erosion per blade is calculated as a function of inlet flow angle for three different particle diameters which are 5, 15 and 60 microns respectively. According to the results of this investigation, for each particle size there is an inlet flow angle for minimum erosion of the guide vanes. This fact has to be accounted for in the design of the radial turbines operating in particulate flow environments.

Study on Film Cooling Performance Improvement of NGV Leading Edge Subject to Distortion Profiles of Low NOx Combustor

2020 ◽  
Author(s):  
Wenhao Zhang ◽  
Zhihao Wang ◽  
Zhiduo Wang ◽  
Zhenping Feng
Keyword(s):  
Film Cooling ◽  
Total Pressure ◽  
Swirling Flow ◽  
Leading Edge ◽  
Pressure Profile ◽  
Flow Angle ◽  
Cooling Performance ◽  
Positive Effects ◽  
Inlet Distortion ◽  
Pressure Profiles

Abstract Under the effect of inlet distortion profiles (including hot-streaks, total pressure profiles, and swirling flow angle patterns), the film cooling performance on the leading edge (LE) region of GE-E3 nozzle guide vanes (NGVs) has been numerically investigated in this paper. Firstly, the complicated inlet distortion profiles of a low NOx combustor chamber has been decoupled to single factors to explore the individual and the coupling effects on the film cooling performance of the NGV LE region (Case 1 to Case 4). Then the original and three modified film-hole configurations are compared and discussed under the quasi-real environment (Case 5 to Case 8). The results indicate that total pressure profile tends to draw more coolant toward the midspan and the residual swirl promotes turnover of the cooling film to the other side of NGVs near the enwalls of LE region. Under the combined effects of different distortion profiles, the cooling film is redistributed on the LE region with some area near the stagnation lines with poor coverage. The upwash or downwash of boundary layer fluid caused by the complicated vortex in passages draws the cooling film on NGV surfaces. And this effect will be strengthened or weakened by the injection angles of holes. Finally, the filmhole configuration in Case 8 with counter-inclined film-hole rows arranged along the stagnation lines shows the best film cooling performance, which has positive effects on the decrease of high temperature region induced by hot streak (HS), and results in more uniform temperature distribution.

Film Cooling Effectiveness Distribution on First-Stage Vane Endwall With and Without Leading-Edge Fillets: Part II—Effect of Incidence Angle

2011 ◽  
Author(s):  
Yang Zhang ◽  
Xin Yuan
Keyword(s):  
Film Cooling ◽  
Incidence Angle ◽  
Leading Edge ◽  
Scale Model ◽  
Cooling Effectiveness ◽  
Flow Angle ◽  
Film Cooling Effectiveness ◽  
Blowing Ratio ◽  
Edge Modification ◽  
Endwall Film Cooling

Using the leading edge airfoil fillet to reduce the aerodynamic loss and surface heat transfer has been proved effective, while the factor of film cooling has not been considered. The first part of the research indicates that the leading edge fillet could improve the film cooling effectiveness through controlling the secondary flow, while this conclusion is restricted to the design condition. The flow field at off-design condition is different from that of the design condition, especially for the structure of horseshoe vortex at the leading edge. It’s possible that the advantage of fillets is not reliable at positive or negative inlet flow angle conditions, which makes the investigation on endwall film cooling with leading edge modification at off-design condition necessary. This paper, which is the second part of a two-part series research investigating the effects of leading edge modification on endwall film cooling, is focused on the performance of fillets at off-design condition. The influence of incidence angle on film cooling effectiveness is studied on first-stage vane endwall with and without leading-edge fillets. A baseline configuration and three kinds of leading edge airfoil fillets are tested in a low speed four-blade cascade consisting of large scale model of the GE-E3 Nozzle Guide Vane (NGV). The results show that as the incidence angle varies from i = +10 deg to i = −10 deg, at low blowing ratio the film cooling effectiveness decreases near the leading edge suction side for all the leading edge geometries. However, this trend becomes opposite under high blowing ratio that the lowest film cooling effectiveness condition is at the incidence angle of i = +10 deg. Near the leading edge pressure side, the film cooling effectiveness increases as the incidence angle varies from i = +10 deg to i = −10 deg at all blowing ratios in the research. The change of incidence angle causes the peak of laterally averaged effectiveness in this region to shift upstream. The experimental results also indicate that the longfillet has the lowest sensitivity towards incidence angle. As for the main passage endwall, with the incidence angle changing form i = +10 deg to i = −10 deg the averaged film cooling effectiveness increases, while this trend will be eliminated by increasing the blowing ratio.

Effects of an Axisymmetric Contoured Endwall on a Nozzle Guide Vane: Adiabatic Effectiveness Measurements

2010 ◽  
Author(s):  
A. A. Thrift ◽  
K. A. Thole ◽  
S. Hada
Keyword(s):  
Film Cooling ◽  
Guide Vane ◽  
Cooling Effectiveness ◽  
Flow Rates ◽  
Guide Vanes ◽  
Film Cooling Effectiveness ◽  
Adiabatic Effectiveness ◽  
Improved Performance ◽  
Nozzle Guide ◽  
Nozzle Guide Vanes

Gas turbine designs seek improved performance by modifying the endwalls of nozzle guide vanes in the engine hot section. Within the nozzle guide vanes these modifications can be in the form of an axisymmetric contour as the area contracts from the combustor to the turbine. This paper investigates the effect of axisymmetric endwall contouring on the cooling performance of a film cooled endwall. Adiabatic effectiveness measurements were performed in a planar passage for comparison to a contoured passage whereby the exit Reynolds numbers was matched. For the contoured passage, measurements were performed on both the flat endwall and on the contoured endwall. Fully expanded film cooling holes were distributed on the endwall surface preceded by a two-dimensional slot normal to the inlet axis. Results indicated that the coolant coverage from the upstream leakage slot was spread over a larger area of the contoured endwall in comparison to the flat endwall of the planar passage. Film cooling effectiveness on the flat endwall of the contoured passage showed minimal differences relative to the planar passage results. The contracting endwall of the contoured passage, however, showed a significant reduction with average film cooling effectiveness levels approximately 40% lower than the planar passage at low film cooling flow rates. In the case of all endwalls, increasing leakage and film cooling mass flow rates led to an increase in cooling effectiveness and coolant coverage.

Inlet Flow Incidence Effects on the Thermal Performance of Showerhead Cooling in a Nozzle Vane Cascade

2019 ◽  
Author(s):  
H. Abdeh ◽  
G. Barigozzi ◽  
A. Perdichizzi ◽  
M. Henze ◽  
J. Krueckels
Keyword(s):  
Thermal Performance ◽  
Thermal Protection ◽  
Cooling System ◽  
Incidence Angle ◽  
Leading Edge ◽  
Intensity Level ◽  
Inlet Flow ◽  
Flow Angle ◽  
Film Cooling Effectiveness ◽  
Nozzle Vane

Abstract In the present paper, the influence of inlet flow incidence on the thermal performance of a film cooled linear nozzle vane cascade is assessed. Tests have been carried out on a cooled cascade, featuring a showerhead cooling system made of 4 rows of cylindrical holes. The cascade was tested by varying the inlet flow angle in the range ±20° at a high inlet turbulence intensity level (Tu1 = 9%) and at a constant inlet Mach number of 0.12. The thermal characterization of vane leading edge region was obtained through adiabatic film cooling effectiveness measurements. Vane load distributions supported the discussion of the results. Varying the incidence angle in either positive or negative angles, the thermal protection on the vane is reduced while the maximum protection happened at 0° incidence case.

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