Comparison of Turbine Tip Leakage Flow for Flat Tip and Squealer Tip Geometries at High-Speed Conditions

2004 ◽  
Vol 128 (2) ◽  
pp. 213-220 ◽  
Author(s):  
Nicole L. Key ◽  
Tony Arts
Keyword(s):  
Reynolds Number ◽  
High Speed ◽  
Flow Characteristics ◽  
Leakage Flow ◽  
Tip Leakage Flow ◽  
Tip Leakage ◽  
Cascade Arrangement ◽  
Oil Flow ◽  
Blade Tip ◽  
Tip Velocity

The tip leakage flow characteristics for flat and squealer turbine tip geometries are studied in the von Karman Institute Isentropic Light Piston Compression Tube facility, CT-2, at different Reynolds and Mach number conditions for a fixed value of the tip gap in a nonrotating, linear cascade arrangement. To the best knowledge of the authors, these are among the very few high-speed tip flow data for the flat tip and squealer tip geometries. Oil flow visualizations and static pressure measurements on the blade tip, blade surface, and corresponding endwall provide insight to the structure of the two different tip flows. Aerodynamic losses are measured for the different tip arrangements, also. The squealer tip provides a significant decrease in velocity through the tip gap with respect to the flat tip blade. For the flat tip, an increase in Reynolds number causes an increase in tip velocity levels, but the squealer tip is relatively insensitive to changes in Reynolds number.

Comparison of Turbine Tip Leakage Flow for Flat Tip and Squealer Tip Geometries at High-Speed Conditions

2004 ◽  
Author(s):  
Nicole L. Key ◽  
Tony Arts
Keyword(s):  
Reynolds Number ◽  
High Speed ◽  
Flow Characteristics ◽  
Leakage Flow ◽  
Tip Leakage Flow ◽  
Tip Leakage ◽  
Cascade Arrangement ◽  
Oil Flow ◽  
Blade Tip ◽  
Tip Velocity

The tip leakage flow characteristics for flat and squealer turbine tip geometries are studied in the von Karman Institute Isentropic Light Piston Compression Tube facility, CT-2, at different Reynolds and Mach number conditions for a fixed value of the tip gap in a non-rotating, linear cascade arrangement. To the best knowledge of the authors, these are among the very few high-speed tip flow data for the flat tip and squealer tip geometries. Oil flow visualizations and static pressure measurements on the blade tip, blade surface, and on the corresponding endwall provide insight to the structure of the two different tip flows. Aerodynamic losses are measured for the different tip arrangements, also. The squealer tip provides a significant decrease in velocity through the tip gap with respect to the flat tip blade. For the flat tip, an increase in Reynolds number causes an increase in tip velocity levels, but the squealer tip is relatively insensitive to change in Reynolds number.

Tip Leakage Flow Reduction of a Linear Turbine Cascade Using String-Type DBD Plasma Actuators

2018 ◽  
Author(s):  
Takayuki Matsunuma ◽  
Takehiko Segawa
Keyword(s):  
Reynolds Number ◽  
Plasma Actuators ◽  
Leakage Flow ◽  
Turbine Cascade ◽  
Tip Leakage Flow ◽  
Dbd Plasma ◽  
Tip Leakage ◽  
String Type ◽  
Displacement Thickness ◽  
Blade Tip

Tip leakage flow through the small gap between the blade tip of a turbine and the casing endwall reduces the aerodynamic performance. String-type dielectric barrier discharge (DBD) plasma actuators made of silicone printed-circuit board were used for the active control of the tip leakage flow of a linear turbine cascade. Sinusoidal voltage excitation with amplitude varying from 4 kV to 6 kV (peak-to-peak voltage: 8 kVp-p to 12 kVp-p) and fixed frequency of 10 kHz was applied to the plasma actuators. The two-dimensional velocity field in the blade passage was estimated by particle image velocimetry (PIV) under the very low Reynolds number conditions of Re = 7.1 × 103 and 1.42 × 104. The tip leakage flow was reduced by the flow control using plasma actuators. The high turbulence intensity region caused by the tip leakage flow was also reduced. For the quantitative comparisons, the displacement thickness of the absolute velocity distributions was examined. By the flow control of the plasma actuators, the displacement thickness at tip-side gradually decreased as the input voltage increased. Although three types of plasma actuators were used, with thin, thick, and flat electrodes and different ratios of discharge area, the differences in their effect were negligible. The reason for these very small differences in effect is the wide spread of the plasma discharge from the encapsulated electrode in the plasma actuator to the exposed electrode of the blade tip. At the relatively high Reynolds number condition of Re = 1.42 × 104, the effect of the plasma actuator was smaller than that at the lower Reynolds number condition of Re = 7.1 × 103.

Characteristics of Tip Leakage Flow of the Turbine Blade With Cutback Squealer and Coolant Injection

2010 ◽  
Author(s):  
Jianhua Wang ◽  
Yalin Liu ◽  
Xiaochun Wang ◽  
Zhineng Du ◽  
Shijie Yang
Keyword(s):  
Turbine Blade ◽  
Film Cooling ◽  
Flow Characteristics ◽  
Leakage Flow ◽  
Tip Leakage Flow ◽  
Tip Leakage ◽  
Coolant Injection ◽  
Blade Tip ◽  
Film Cooling Holes ◽  
Numerical Program

Experimental and numerical investigations of the tip leakage flow characteristics between turbine blade tip and stator wall (shroud) were conducted by a particle image velocimetry (PIV) system and the commercially available software CFX 11.0. A three-time scaled profile of the GE-E3 blade was used as specimen. Two rows of cylindrical film-cooling holes with 1.5mm diameter were arranged in the blade tip. One row with 5 holes was placed in pressure side just below the groove floor, and the other with 11 holes was equidistantly arranged on the tip along the mid camber line. To exhibit the generation and movement of leakage vortex, and to compare the coolant injection effects from different rows, several typical velocity profiles were captured by the PIV system. The experimental results were used as a data source to validate the turbulence model and numerical program. To better understand the mixing characteristics of the coolant injected from different rows with the leakage flow, the fluid fields of the leakage vortex and coolant flow were simulated, and the leakage mass rates from the blade tip in different coolant injection cases and different gaps were quantitatively estimated by the validated numerical program.

J051052 tudy on the Tip Leakage Flow in Linear Compressor Cascade : Effects of Blade Tip Clearance and Tip Velocity)

2011 ◽  
Vol 2011 (0) ◽  
pp. _J051052-1-_J051052-4
Author(s):  
Kazunari MATSUDA ◽  
Kenichi FUNAZAKI ◽  
Hideo TANIGUCHI ◽  
Hiromasa KATO ◽  
Masafumi KUMAGAI ◽  
...  
Keyword(s):  
Tip Clearance ◽  
Leakage Flow ◽  
Compressor Cascade ◽  
Tip Leakage Flow ◽  
Tip Leakage ◽  
Blade Tip ◽  
Cascade Effects ◽  
Linear Compressor Cascade ◽  
Tip Velocity ◽  
Blade Tip Clearance

Experimental Study on Internal Flow Field of a High-Speed Centrifugal Compressor at Different Altitudes

2020 ◽  
Author(s):  
Xinghang Yu ◽  
Hongwei Ma ◽  
Lei Shi ◽  
Lianpeng Zhao
Keyword(s):  
Centrifugal Compressor ◽  
High Speed ◽  
Pressure Sensors ◽  
Leakage Flow ◽  
High Altitudes ◽  
Tip Leakage Flow ◽  
Tip Leakage ◽  
Blade Tip ◽  
Low Altitude ◽  
Different Altitudes

Abstract The alteration of altitude will affect the stability of centrifugal compressors. In this paper, the pressure field on the casing wall of a high-speed centrifugal compressor at two different altitudes (h = 0m and h = 4500m) was investigated by using 15 high-response pressure sensors. The operating condition of the centrifugal compressor ranged from choke condition to developed stall condition. The results show that the interaction of the shock wave and splitter-blade tip leakage flow occurs at 70% chord region near the choke condition, and the loss is more severe at the high altitudes. At the near-stall condition, the unstable disturbance at the low altitude is caused by the collapse of the horseshoe vortex, and the unstable disturbance at the high altitude is dominated by advanced breakdown of the main-blade tip leakage vortex. At the developed-stall condition, the stall mechanisms at the two altitudes are different, both of which are closely related to the main-blade tip leakage flow. With the decrease of flow rate, the unsteady disturbance caused by the volute tongue moves upstream from the diffuser to the impeller inlet. At the same time, the unsteady disturbance propagates along the opposite direction of the rotational direction in the partial impeller passage at the low altitude case. However, the circumferential propagation characteristics at the high altitudes case are not obvious.

Investigation of Leakage Flow and Heat Transfer in a Gas Turbine Blade Tip With Emphasis on the Effect of Rotation

2008 ◽  
Author(s):  
Dianliang Yang ◽  
Xiaobing Yu ◽  
Zhenping Feng
Keyword(s):  
Heat Transfer ◽  
Relative Motion ◽  
Turbulence Models ◽  
Leakage Flow ◽  
Tip Leakage Flow ◽  
Blade Height ◽  
Tip Leakage ◽  
Flow And Heat Transfer ◽  
Blade Rotation ◽  
Blade Tip

In this paper, numerical methods have been applied to the investigation of the effect of rotation on the blade tip leakage flow and heat transfer. Using the first stage rotor blade of GE-E3 engine high pressure turbine, both flat tip and squealer tip have been studied. The tip gap height is 1% of the blade height, and the groove depth of the squealer tip is 2% of the blade height. Heat transfer coefficient on tip surface obtained by using different turbulence models was compared with experimental results. And the grid independence study was carried out by using the Richardson extrapolation method. The effect of the blade rotation was studied in the following cases: 1) blade domain is rotating and shroud is stationary; 2) blade domain is stationary and shroud is rotating; and 3) both blade domain and shroud are stationary. In this approach, the effects of the relative motion of the endwall, the centrifugal force and the Coriolis force can be investigated respectively. By comparing the results of the three cases discussed, the effects of the blade rotation on tip leakage flow and heat transfer are revealed. It indicated that the main effect of the rotation on the tip leakage flow and heat transfer is resulted from the relative motion of the shroud, especially for the squealer tip blade.

Experimental and Numerical Study of Honeycomb Tip on Suppressing Tip Leakage Flow in Turbine Cascade

2017 ◽  
Author(s):  
Yunfeng Fu ◽  
Fu Chen ◽  
Huaping Liu ◽  
Yanping Song
Keyword(s):  
Numerical Study ◽  
Flow Characteristics ◽  
Leakage Flow ◽  
Exit Section ◽  
Turbine Cascade ◽  
Tip Leakage Flow ◽  
Physical Processes ◽  
Tip Leakage ◽  
Gap Height ◽  
Positive Effect

In this paper, the effect of a novel honeycomb tip on suppressing tip leakage flow in a highly-loaded turbine cascade has been experimentally and numerically studied. The research focuses on the mechanisms of honeycomb tip on suppressing tip leakage flow and affecting the secondary flow in the cascade, as well as the influences of different clearance heights on leakage flow characteristics. In addition, two kinds of local honeycomb tip structures are pro-posed to explore the positive effect on suppressing leakage flow in simpler tip honeycomb structures. Based on the experimental and numerical results, the physical processes of tip leakage flow and its interaction with main flow are analyzed, the following conclusions can be obtained. Honeycomb tip rolls up a number of small vortices and radial jets in regular hexagonal honeycomb cavities, increasing the flow resistance in the clearance and reducing the velocity of leakage flow. As a result, the structure of honeycomb tip not only suppresses the leakage flow effectively, but also has positive effect on reducing the associated losses in cascade by reducing the strength of leakage vortex. Compare to the flat tip cascade at 1%H gap height, the relative leakage flow in honeycomb tip cascade reduces from 3.05% to 2.73%, and the loss at exit section is also decreased by 10.63%. With the increase of the gap height, the tip leakage flow and loss have variations of direct proportion with it, but their growth rates in the honeycomb tip cascade are smaller. Consider the abradable property of the honeycomb seal, a smaller gap height is allowed in the cascade with honeycomb tip, and that means honeycomb tip has better effect on suppressing leakage flow. Two various local honeycomb tip structures has also been discussed. It shows that local raised honeycomb tip has better suppressing leakage flow effect than honeycomb tip, while local concave honeycomb tip has no more effect than honeycomb tip. Compare to flat tip cascade, the leakage flow in honeycomb tip cascade, local concave tip cascade and local raised honeycomb tip cascade decrease by nearly 17.33%, 15.51% and 30.86% respectively, the losses at exit section is reduced by 13.38%, 12% and 28.17% respectively.

On the Recessed Blade Tip With and Without a Porous Material in an Axial Compressor

2014 ◽  
Author(s):  
Young-Jin Jung ◽  
Tae-Gon Kim ◽  
Minsuk Choi
Keyword(s):  
Porous Material ◽  
Axial Compressor ◽  
Internal Flow ◽  
Leakage Flow ◽  
Tip Leakage Flow ◽  
Flow Solver ◽  
Stall Margin ◽  
Tip Leakage ◽  
Blade Tip ◽  
Strong Vortex

This paper addresses the effect of the recessed blade tip with and without a porous material on the performance of a transonic axial compressor. A commercial flow solver was employed to analyze the performance and the internal flow of the axial compressor with three different tip configurations: reference tip, recessed tip and recessed tip filled with a porous material. It was confirmed that the recessed blade tip is an effective method to increase the stall margin in an axial compressor. It was also found in the present study that the strong vortex formed in the recess cavity on the tip pushed the tip leakage flow backward and weakened the tip leakage flow itself, consequently increasing the stall margin without any penalty of the efficiency in comparison to the reference tip. The recessed blade tip filled with a porous material was suggested with hope to obtain the larger stall margin and the higher efficiency. However, it was found that a porous material in the recess cavity is unfavorable to the performance in both the stall margin and the efficiency. An attempt has been made to explain the effect of the recess cavity with and without a porous material on the flow in an axial compressor.

Aerodynamic Performance of Blade Tip End-Plates Designed for Low-Noise Operation in Axial Flow Fans

2009 ◽  
Vol 131 (8) ◽  
Author(s):  
Alessandro Corsini ◽  
Franco Rispoli ◽  
A. G. Sheard
Keyword(s):  
Flow Behavior ◽  
Acoustic Emissions ◽  
Axial Flow ◽  
Low Noise ◽  
Leakage Flow ◽  
Tip Leakage Flow ◽  
Tip Leakage ◽  
Leakage Flows ◽  
Blade Tip ◽  
Tip Leakage Flows

This study assesses the effectiveness of modified blade-tip configurations in achieving passive noise control in industrial fans. The concepts developed here, which are based on the addition of end-plates at the fan-blade tip, are shown to have a beneficial effect on the fan aeroacoustic signature as a result of the changes they induce in tip-leakage-flow behavior. The aerodynamic merits of the proposed blade-tip concepts are investigated by experimental and computational studies in a fully ducted configuration. The flow mechanisms in the blade-tip region are correlated with the specific end-plate design features, and their role in the creation of overall acoustic emissions is clarified. The tip-leakage flows of the fans are analyzed in terms of vortex structure, chordwise leakage flow, and loading distribution. Rotor losses are also investigated. The modifications to blade-tip geometry are found to have marked effects on the multiple vortex behaviors of leakage flow as a result of changes in the near-wall fluid flow paths on both blade surfaces. The improvements in rotor efficiency are assessed and correlated with the control of tip-leakage flows produced by the modified tip end-plates.

Sign in / Sign up

Export Citation Format

Share Document