Numerical Investigations on the Effect of Pivot Shapes in Part Clearance Flow Field of Variable Area LP Turbine Nozzle Vane

2020 ◽  
Author(s):  
Hardikkumar Bhavsar ◽  
Chetan S. Mistry
Keyword(s):  
Turbine Engines ◽  
Leakage Flow ◽  
Gas Turbine Engines ◽  
Power Demand ◽  
Pressure Loss Coefficient ◽  
Clearance Flow ◽  
Different Shapes ◽  
Lp Turbine ◽  
Total Pressure Loss Coefficient ◽  
Better Than

Abstract The performance of the gas turbine engines deteriorates under off-design conditions with the change of required power demand. The performance of the engine can be improved by actively controlling the mass flow rate through the engine turbine section using the variable area nozzle turbine (VANT). However, to implement VANT, vanes of the turbine nozzle need to be rotated, which demands part clearance to be provided near both the hub and tip region. In order to keep constant part clearance during vane turning, endwalls are modified to spherical shapes in such a way that distance between vane and upstream as well downstream rotor remains unaffected. Also, vanes are rotated about its pivot, which creates a blockage to the leakage flow in the part clearance. As pivot creates a blockage to the leakage flow, the shape of the pivot need to be selected in such a way that leakage losses can be reduced effectively. Hence, to analyze the effect of different pivot shapes on leakage losses, two different shapes of the pivot i.e., circular and elliptic, are explored in the present study. Also, three vane turning angles are analyzed to observe the effectiveness of these pivot shapes. The effect of the pivot is analyzed by entropy contours and total pressure loss coefficient in the exit plane, and it is found that the elliptic pivot performs better than a circular pivot as an elliptic pivot provides more blockage to the leakage flow and hence minimizing the overall losses.

Investigation of a Tip Clearance Cascade in a Water Analogy Rig

1986 ◽  
Vol 108 (1) ◽  
pp. 38-46 ◽  
Author(s):  
J. A. H. Graham
Keyword(s):  
Turbine Blades ◽  
Flow Region ◽  
Tip Clearance ◽  
Turbine Engines ◽  
Gas Turbine Engines ◽  
Tip Clearance Flow ◽  
Pressure Profiles ◽  
Clearance Flow ◽  
Hot Film ◽  
Model Features

The tip clearance flow region of high-pressure axial turbine blades for small gas turbine engines has been investigated in a water flow cascade. The blade model features variable clearance and variable endwall speeds. The cascade is scaled for Reynolds number and sized to give velocities suitable for visualization. Pressure profiles were measured on one blade, and correlated with the visualization. Unloading is found to be a major feature of the pressure field at both tip and midspan, and is intimately connected with scraping effects and the behavior of the clearance vortex. Some initial hot-film velocity measurements are also presented.

Different Effects of Cantilevered and Shrouded Stators on Axial Compressor Performance

2017 ◽  
Author(s):  
Xiayi Si ◽  
Jinfang Teng ◽  
Xiaoqing Qiang ◽  
Jinzhang Feng
Keyword(s):  
Pressure Loss ◽  
Total Pressure ◽  
Loss Coefficient ◽  
Total Pressure Loss ◽  
Axial Position ◽  
Leakage Flow ◽  
Flow Angle ◽  
Design Point ◽  
Pressure Loss Coefficient ◽  
Total Pressure Loss Coefficient

Numerical simulations with the steady 3D RANS were performed on the rear stage of a modern high pressure compressor. The labyrinth seal cavity model of the shrouded stator was simplified according to the actual stator structure, which the seal cavity gap is 1% of blade height. Several typical configurations (shrouded stator, idealized stator and cantilevered stators) were designed and carried out, and cantilevered stators contained no gap, small gap (CS1%), design gap (CS2.5%) and large gap (CS4%/CS5%). The results indicate due to the effect of leakage flow from 1% span seal cavity gap, the total pressure loss of SS is larger than IS, while IS instead of SS in the process of the compressor design, the stall margin will be enlarged nearly 6% numerically. At the design point, when the hub gap is 3.5% span clearance CS has the same loss with IS, and when the hub gap is 4.5% span clearance CS has almost the same loss with SS. Among all operation range, the total pressure loss of S1 increases with the increase of the hub clearance. When the hub gap is 0 (CS0), there is no leakage flow and the loss is the least. At the design point, comparing with SS, the total pressure loss coefficient of CS0 decreases 18.34%, CS2.5% decreases 8.46% and IS decreases 6.45%. It means if the cantilevered stator with 2.5% span hub clearance were adopted in the HPC, the performance would be better than the shrouded stator. However, because of the matching condition, the rotor that follows after cantilevered stator should be redesigned according to blade loading and inlet flow angle changed. The performance of cantilevered stator is impacted of various hub clearance, the loss below 25% span increases significantly with hub clearance, the maximum value of outlet flow angle deviation is 2.3 degree. The stator hub peak loading is shifted upstream toward the leading edge when hub clearance size is increased. The total pressure loss coefficient and pressure coefficient at different axial position had the function relation. When the hub clearance increases, the position of double leakage flow start backwards, in the rear part of stator the secondary flow becomes stronger leading to more mixing loss and lower total pressure.

Effect of arbitrary blade tip design on tip leakage flow

2019 ◽  
Vol 234 (1) ◽  
pp. 19-30
Author(s):  
Jiahui Jin ◽  
Yanping Song ◽  
Jianyang Yu ◽  
Fu Chen
Keyword(s):  
Flow Rate ◽  
Total Pressure ◽  
Leakage Flow ◽  
Exit Section ◽  
Turbine Cascade ◽  
Tip Leakage Flow ◽  
Tip Leakage ◽  
Pressure Loss Coefficient ◽  
Blade Tip ◽  
Total Pressure Loss Coefficient

Tip geometry modification is frequently used to suppress the tip leakage flow in the turbine cascade however a universally beneficial tip geometry modification design has not been fully discovered. In this paper, the two-surface coupling arbitrary blade tip design method in three-dimensional physical space which satisfies the simple trigonometric function law is proposed and the mathematical parametric description is presented. The effects of different arbitrary blade tips on tip leakage flow have been studied numerically in a highly loaded axial turbine cascade. The aerodynamic performance of different tips is assessed by the tip leakage mass flow rate and the total pressure loss coefficient at the exit section. The Kriging model and genetic optimization algorithm are used to optimize the arbitrary blade tips to obtain the optimal arbitrary blade tip. Compared with the flat tip, the tip leakage mass flow rate is decreased by 10.57% and the area-average total pressure loss coefficient at the exit section is reduced by 8.91% in the optimal arbitrary blade tip.

Numerical Investigation on the Effect of Slot Leakage on a NGV With 2D Contoured Endwall: Adiabatic Effectiveness and Aerodynamic Loss

2017 ◽  
Author(s):  
Pingting Chen ◽  
Xueying Li ◽  
Jing Ren ◽  
Hongde Jiang
Keyword(s):  
Numerical Method ◽  
Main Flow ◽  
Secondary Flows ◽  
Leakage Flow ◽  
Experiment Data ◽  
Aerodynamic Loss ◽  
Pressure Loss Coefficient ◽  
Adiabatic Effectiveness ◽  
Total Pressure Loss Coefficient ◽  
Typical Design

Endwall 2D contouring is a typical design to reduce the strength of secondary flows within the passage. Such contouring can lead to significant changes in the passage flow. A leakage slot at the combustor-turbine interface is a typical turbine endwall design. The leakage flow can be used to cool the endwall and vane surface. Moreover, the leakage flow interacts with the main flow and results in the change of aerodynamic loss. A 3D numerical method was used to investigate endwall adiabatic effectiveness and passage total pressure loss coefficient (TPLC) on a NGV with 2D contoured endwall under a series of mass flow ratios (MFRs). The numerical method was validated by comparision with the experiment data. The results indicate that under the condition of this study, When MFR<0.625%, there is ingestion, and when 0.625%<MFR<1.0%, the TPLC is high. When 0.875%<MFR<1.0%, the area averaged adiabatic effectiveness (AAAE) decreases and the TPLC stays high as the MFR increases. When 1.0%<MFR<1.5%, the adiabatic effectiveness is high and the TPLC is low. To accomplish high adiabatic effectiveness, low aerodynamic loss and slight ingestion, the recommended range of MFR is 1.0%<MFR<1.5%.

scholarly journals Investigation of a Tip Clearance Cascade in a Water Analogy Rig

1985 ◽  
Author(s):  
J. A. H. Graham
Keyword(s):  
Turbine Blades ◽  
Flow Region ◽  
Tip Clearance ◽  
Turbine Engines ◽  
Gas Turbine Engines ◽  
Tip Clearance Flow ◽  
Pressure Profiles ◽  
Clearance Flow ◽  
Hot Film ◽  
Model Features

The tip clearance flow region of high pressure axial turbine blades for small gas turbine engines has been investigated in a water flow cascade. The blade model features variable clearance and variable endwall speeds. The cascade is scaled for Reynolds number and sized to give velocities suitable for visualization. Pressure profiles were measured on one blade, and correlated with the visualization. Unloading is found to be a major feature of the pressure field at both tip and midspan, and is intimately connected with scraping effects and the behavior of the clearance vortex. Some initial hot film velocity measurements are also presented.

Gas Screen in Components of Gas Turbine Engines

1997 ◽  
Vol 28 (7-8) ◽  
pp. 536-542
Author(s):  
A. A. Khalatov ◽  
I. S. Varganov
Keyword(s):  
Gas Turbine ◽  
Turbine Engines ◽  
Gas Turbine Engines ◽  
Gas Screen

Potential Application of Composite Materials to Future Gas Turbine Engines

1988 ◽  
Author(s):  
James C. Birdsall ◽  
William J. Davies ◽  
Richard Dixon ◽  
Matthew J. Ivary ◽  
Gary A. Wigell
Keyword(s):  
Composite Materials ◽  
Gas Turbine ◽  
Potential Application ◽  
Turbine Engines ◽  
Gas Turbine Engines

PYROMET ALLOY CTX-1

Alloy Digest ◽  
1997 ◽  
Vol 46 (5) ◽  
Keyword(s):  
Coefficient Of Thermal Expansion ◽  
High Strength ◽  
Heat Treating ◽  
Turbine Engines ◽  
Gas Turbine Engines ◽  
Thermal Fatigue Resistance ◽  
Temperature Performance ◽  
Hot Work Die ◽  
Pressure Hydrogen ◽  
Hot Hardness

Abstract Pyromet CTX-1 is a high-strength, precipitation-hardenable superalloy exhibiting a low coefficient of thermal expansion and high strength up to about 1200 deg F. The alloy possesses high hot hardness and good thermal fatigue resistance. Its applications include components for gas turbine engines, hot-work die applications and high-pressure hydrogen environments. This datasheet provides information on composition, physical properties, hardness, elasticity, and tensile properties as well as creep. It also includes information on high temperature performance and corrosion resistance as well as forming, heat treating, machining, and joining. Filing Code: FE-56. Producer or source: Carpenter. Originally published February 1976, revised May 1997.

HAYNES ALLOY 75

Alloy Digest ◽  
1999 ◽  
Vol 48 (7) ◽  
Keyword(s):  
Mechanical Properties ◽  
High Temperature ◽  
Heat Treating ◽  
Turbine Engines ◽  
Chromium Alloy ◽  
Gas Turbine Engines ◽  
Typical Application ◽  
Good Oxidation Resistance ◽  
Temperature Performance ◽  
Haynes Alloy

Abstract Haynes alloy 75 is an 80 nickel-20 chromium alloy with both good oxidation resistance and good mechanical properties at high temperatures. It is amenable to all forms of fabrication and welding. A typical application for sheet metal is fabrications in gas turbine engines. This datasheet provides information on composition, physical properties, elasticity, and tensile properties as well as creep. It also includes information on high temperature performance as well as forming and heat treating. Filing Code: Ni-557. Producer or source: Haynes International Inc.

Sign in / Sign up

Export Citation Format

Share Document