Effects of Blade Tip Geometries on the Aerodynamic Performance of a Compressor Cascade

2013 ◽  
Author(s):  
Hongwei Ma ◽  
Jun Zhang ◽  
Wei Wei
Keyword(s):  
Pressure Rise ◽  
Suction Side ◽  
Leakage Flow ◽  
Pressure Side ◽  
Compressor Cascade ◽  
Turning Angle ◽  
Blade Loading ◽  
Blade Width ◽  
Blade Tip ◽  
Greater Curvature

This paper presents a numerical simulation of effects of blade tip geometries on the flow field of a compressor cascade. The tip geometries include flat tip (baseline), tip with cavity, tip with pressure side extension and suction side squealer tip. For the tip with cavity and pressure side extension, the mass of the leakage flow is reduced. The loss in the tip gap of the cavity tip is greater than the baseline because of the interaction of the cavity flow and the leakage flow. For the tip with pressure side extension, the loss in the gap is also greater than the baseline. The main reason is that the greater blade width makes the mixing process of the leakage flow in the gap more sufficient than the baseline. For both these two cases, the turning angle of the cascade becomes smaller and the pressure rise of the cascade is lower than the flat tip case. For the suction side squealer tip, the greater curvature of squealer increases the blade loading. The turning angle of the cascade and the pressure rise becomes greater which increases total pressure loss slightly.

Experimental Study of Effects of Grooved Tip Clearances on the Flow Field in a Compressor Cascade Passage

2010 ◽  
Author(s):  
Hongwei Ma ◽  
Jun Zhang ◽  
Jinghui Zhang ◽  
Zhou Yuan
Keyword(s):  
Flow Field ◽  
Large Scale ◽  
Suction Side ◽  
Tip Clearance ◽  
Pressure Probe ◽  
Leakage Flow ◽  
Compressor Cascade ◽  
High Loss ◽  
Static Pressure Distribution ◽  
Blade Tip

This paper presents an experimental investigation of effects of grooved tip clearances on the flow field of a compressor cascade. The tests were performed in a low-speed large-scale cascade respectively with two tip clearance configurations, including flat tip and grooved tip with a chordwise channel on the blade top. The flow field at 10% chord downstream from the cascade trailing edge was measured at four incidence angles using a mini five-hole pressure probe. The static pressure distribution was measured on the tip endwall. The results show that the pressure gradient from the pressure side to the suction side on the blade tip is reduced due to the existence of the channel. As a result, the leakage flow is weakened. The high-blockage and high-loss region caused by the leakage flow is narrower with the grooved tip. In the meantime, the leakage flow migrates to lower spanwise position. The combined result is that the flow capacity in the tip region is improved at the incidence angles of 0° and 5° with the grooved tip. However, the loss is slightly greater than that with the flat tip at all the incidence angles.

Numerical Simulation of Effects of Tip Geometry on the Performance of an Axial Compressor

2012 ◽  
Author(s):  
Hongwei Ma ◽  
Jun Zhang
Keyword(s):  
Mass Flow ◽  
Tangential Force ◽  
Axial Compressor ◽  
Pressure Rise ◽  
Leading Edge ◽  
Suction Side ◽  
Leakage Flow ◽  
Base Line ◽  
Compressor Rotor ◽  
Blade Tip

The purpose of this paper is to investigate numerically the effects of the tip geometry on the performance of an axial compressor rotor. There are three case studies which are compared with the base line tip geometry. 1) baseline (flat tip); 2) Cavity (tip with a cavity); 3) SSQA (suction side squealer tip) and 4) SSQB (modified suction side squealer tip). The case of SSQB is a combination of suction side squealer tip and the cavity tip. From leading edge to 10% chord, the tip has a cavity. From 10% chord to trailing edge, the tip has a suction side squealer. The numerical results of 2) show that the cavity tip leads to lower leakage mass flow and greater loss in tip gap and the rotor passage. The loading near the blade tip is lower than the baseline, thus the tangential force of the blade is lower. It leads to lower pressure rise than the baseline. The performance of the compressor for the tip with cavity is worse than the baseline. The results of 3) show that the higher curvature of the suction side squealer increases the loading of the blade and the tangential blade force. With the suction side squealer tip, the leakage flow experiences two vena contractor thus the mass of the leakage flow is reduced which is benefit for the performance of the compressor. The loss in the tip gap is lower than baseline. The performance is better than the baseline with greater pressure rise of the rotor, smaller leakage mass flow and lower averaged loss. For the case the SSQB, the leakage mass flow is lower than the SSQA and the loss in the tip gap and the rotor passage is greater than SSQA. The performance of the case of the SSQB is worse than the case of SSQA.

Numerical Study of Flow and Heat Transfer on a Blade Tip With Different Leakage Reduction Strategies

2003 ◽  
Author(s):  
Sumanta Acharya ◽  
Huitao Yang ◽  
Chander Prakash ◽  
Ron Bunker
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Suction Side ◽  
Leakage Flow ◽  
Pressure Side ◽  
Flow Rates ◽  
Leakage Reduction ◽  
Flow And Heat Transfer ◽  
Reduction Strategies ◽  
Blade Tip

Numerical calculations are performed to explore different strategies for reducing tip leakage flow and heat transfer on the GE-E3 High-Pressure-Turbine (HPT) rotor blade. The calculations are performed for a single blade with periodic conditions imposed along the two boundaries in the circumferential-pitch direction. Several leakage reduction strategies are considered, all for a tip-clearance of 1.5% of the blade span, a pressure ratio (ratio of inlet total pressure to exit static pressure) of 1.2, and an inlet turbulence level of 6.1%. The first set of leakage reduction strategies explored include different squealer tip configurations: pressure-side squealer, suction-side squealer, mean-camber line squealer, and pressure plus suction side squealers located either along the edges of the blade or moved inwards. The suction-side squealer is shown to have the lowest heat transfer coefficient distribution and the lowest leakage flow rates. Two tip-desensitization strategies are explored. The first strategy involves a pressure-side winglet shaped to be thickest at the location with the largest pressure difference across the blade. The second strategy involves adding inclined ribs on the blade tip with the ribs normal to the local flow direction. While both strategies lead to reduction in the leakage flow and tip heat transfer rates, the ribbed tip exhibits considerably lower heat transfer coefficients. In comparing the two desensitization schemes with the various squealer tip configurations, the suction side squealer still exhibits the lowest heat transfer coefficient and leakage flow rates.

Numerical Investigation of Tip Clearance Flow in an Axial Compressor Cascade

2014 ◽  
Vol 599-601 ◽  
pp. 368-371
Author(s):  
Zhi Hui Xu ◽  
He Bin Lv ◽  
Ru Bin Zhao
Keyword(s):  
Computational Simulation ◽  
Suction Side ◽  
Tip Clearance ◽  
Leakage Flow ◽  
Compressor Cascade ◽  
Tip Leakage Flow ◽  
Tip Clearance Flow ◽  
Tip Leakage ◽  
Clearance Flow ◽  
Blade Tip

Using blade tip winglet to control the tip leakage flow has been concerned in the field of turbomachinery. Computational simulation was conducted to investigate the phenomenological features of tip clearance flow. The simulation results show that suction-side winglet can reduce leakage flow intensity. The tip winglet can also decrease tip leakage mass flow and weaken tip leakage flow mixing with the mainstream and therefore reduce the total pressure loss at the blade tip.

Effect of Surface Roughness Location and Reynolds Number on Compressor Cascade Performance

2010 ◽  
Author(s):  
Seung Chul Back ◽  
Garth V. Hobson ◽  
Seung Jin Song ◽  
Knox T. Millsaps
Keyword(s):  
Surface Roughness ◽  
Reynolds Number ◽  
Leading Edge ◽  
Suction Side ◽  
Pressure Side ◽  
Compressor Cascade ◽  
Suction Surface ◽  
Trailing Edge ◽  
Blade Loading ◽  
Linear Compressor Cascade

An experimental investigation has been conducted to characterize the influence of surface roughness location and Reynolds number on compressor cascade performance. Flow field surveys have been conducted in a low-speed, linear compressor cascade. Pressure, velocity, and flow angles have been measured via a 5-hole probe, pitot probe, and pressure taps on the blades. In addition to the entirely smooth and entirely rough blade cases, blades with roughness covering the leading edge; pressure side; and 5%, 20%, 35%, 50%, and 100% of suction side from the leading edge have been studied. All of the tests have been done for Reynolds number ranging from 300,000 to 640,000.Cascade performance (i.e. blade loading, loss, and deviation) is more sensitive to roughness on the suction side than pressure side. Roughness near the trailing edge of suction side increases loss more than that near the leading edge. When the suction side roughness is located closer to the trailing edge, the deviation and loss increase more rapidly with Reynolds number. For a given roughness location, there exists a Reynolds number at which loss begins to visibly increase. Finally, increasing the area of rough suction surface from the leading edge reduces the Reynolds number at which the loss coefficient begins to increase.

Effects of Reynolds Number and Surface Roughness Magnitude and Location on Compressor Cascade Performance

2012 ◽  
Vol 134 (5) ◽  
Author(s):  
Seung Chul Back ◽  
Garth V. Hobson ◽  
Seung Jin Song ◽  
Knox T. Millsaps
Keyword(s):  
Surface Roughness ◽  
Reynolds Number ◽  
Leading Edge ◽  
Side Surface ◽  
Suction Side ◽  
Reynolds Numbers ◽  
Pressure Side ◽  
Compressor Cascade ◽  
Suction Surface ◽  
Blade Loading

An experimental investigation has been conducted to characterize the influence of Reynolds number and surface roughness magnitude and location on compressor cascade performance. Flow field surveys have been conducted in a low-speed, linear compressor cascade. Pressure, velocity, and loss have been measured via a five-hole probe, pitot probe, and pressure taps on the blades. Four different roughness magnitudes, Ra values of 0.38 μm (polished), 1.70 μm (baseline), 2.03 μm (rough 1), and 2.89 μm (rough 2), have been tested. Furthermore, various roughness locations have been examined. In addition to the as manufactured (baseline) and entirely rough blade cases, blades with roughness covering the leading edge, pressure side, and 5%, 20%, 35%, 50%, and 100% of suction side from the leading edge have been studied. All of the tests have been carried out for Reynolds numbers ranging from 300,000 to 640,000. For Reynolds numbers under 500,000, the tested roughnesses do not significantly degrade compressor blade loading or loss. However, loss and blade loading become sensitive to roughness at Reynolds numbers above 550,000. Cascade performance is more sensitive to roughness on the suction side than pressure side. Furthermore, roughness on the aft 2/3 of suction side surface has a greater influence on loss. For a given roughness location, there exists a Reynolds number at which loss begins to significantly increase. Finally, increasing the roughness area on the suction surface from the leading edge reduces the Reynolds number at which the loss begins to increase.

Influence of Different Rim Widths and Blowing Ratios on Film Cooling Characteristics for a Blade Tip

2012 ◽  
Vol 134 (6) ◽  
Author(s):  
Jin Wang ◽  
Bengt Sundén ◽  
Min Zeng ◽  
Qiu-wang Wang
Keyword(s):  
Heat Transfer ◽  
Numerical Simulations ◽  
Film Cooling ◽  
Three Dimensional ◽  
Suction Side ◽  
Leakage Flow ◽  
Pressure Side ◽  
Tip Leakage Flow ◽  
Blade Tip ◽  
Film Cooling Holes

Three-dimensional simulations of the squealer tip on the GE-E3 blade with eight film cooling holes were carried out. The effect of the rim width and the blowing ratio on the blade tip flow and cooling performance were revealed. Numerical simulations were performed to predict the leakage flow and the tip heat transfer with the k–ɛ model. For the squealer tip, the depth of the cavity is fixed but the rim width varies to form a wide cavity, which can decrease the coolant momentum and the tip leakage flow velocity. This cavity contributes to the improvement of the cooling effect in the tip zone. To investigate the influence on the tip heat transfer by the rim width, numerical simulations were performed as a two-part study: (1) unequal rim width study on the pressure side and the suction side and (2) equal rim width study with rim widths of 0.58%, 1.16%, and 1.74% of the axial chord (0.5 mm, 1 mm, and 1.5 mm, respectively) on both the pressure side rim and the suction side rim. With different rim widths, the effect of different global blowing ratios, i.e., M = 0.5, 1.0 and 1.5, was investigated. It is found that the total heat transfer rate is increasing and the heat transfer rates on the rim surface (RS) rapidly ascend with increasing rim width.

Reduction of Tip Clearance Losses in an Axial Turbine by Shaped Design of the Blade Tip Region

2007 ◽  
Author(s):  
K. Kusterer ◽  
N. Moritz ◽  
D. Bohn ◽  
T. Sugimoto ◽  
R. Tanaka
Keyword(s):  
Numerical Investigation ◽  
Mass Flow ◽  
Suction Side ◽  
Tip Clearance ◽  
Leakage Flow ◽  
Pressure Side ◽  
Aerodynamic Efficiency ◽  
Blade Tip ◽  
Radial Gap ◽  
Tip Clearance Vortex

Secondary flows and leakage flows lead to complex vortex structures in the flow field inside the passages of the vanes and blades in turbo machines. These result in aerodynamic losses and, thus, reduced efficiency. One of the major vortex structures is the tip clearance vortex, which is generated on the airfoil’s suction side due to the leakage flow through the tip clearance, e.g. between rotating blades and casing. This leakage flow is induced by the pressure difference between pressure and suction side. The tip clearance vortex intensity strongly depends on the amount of tip clearance leakage. Thus, the reduction of this leakage mass flow increases the aerodynamic efficiency of a turbo-machine. In gas turbines, two ways are commonly used to influence the tip leakage flow: contouring of the radial gap either at blade tip or endwall, or changing the blade tip geometry by application of squealers or winglets on the blade tip. In this paper, a numerical investigation on the principle physics of a specific blade tip design is presented. On the pressure side the blades are extended in the tip region comparable to winglets (“hook-shaped”). With this change, the structures of the flow entering the gap between blade tip and casing are influenced to achieve a reduction of the mass flow in the radial gap. In this approach, the contour of the blade on the pressure side surface is shaped smoothly so that only a low increase of the local stresses should be expected and the blade is manufactured in one part. Furthermore, the height of the tip clearance is not affected. The new blade tip design is applied to 2nd and 3rd blade of the axial turbine in a test configuration of a KHI industrial gas turbine. Thus, a multi-stage numerical approach has been selected for the numerical investigation. The numerical model includes the flow path, vanes and blades of the 2nd and 3rd stage. The mixing plane technique is used to couple the blocks computed in stationary system of reference and rotating system of reference. The aerodynamic efficiency of the new designed blade tip in the two-stage arrangement is compared to the original design. It shows that a slight increase can be achieved in the static polytropic efficiency of the turbine configuration. The influence of the new design on the flow structures in the tip clearance region of the blades is analysed in detail to explain the mechanisms that cause the efficiency increase.

Modeling of Blade Tip Geometries in an Axial Compressor Stage

2003 ◽  
Author(s):  
Carsten Stockhaus ◽  
Werner Volgmann ◽  
Horst Stoff
Keyword(s):  
Beneficial Effect ◽  
Axial Compressor ◽  
Suction Side ◽  
Tip Clearance ◽  
Leakage Flow ◽  
Efficiency Gain ◽  
Pressure Side ◽  
Compressor Stage ◽  
Tip Leakage Flow ◽  
Blade Tip

The purpose of this paper is to investigate numerically the tip leakage flow for different blade tip geometries in an axial compressor stage under design and off-design conditions. Using flat tips, suction and pressure side squealers in combination with knife tips, a comparison of the rotor performance in terms of pressure and efficiency gain is reported. Detailed flow characteristics within the tip clearance gap, interaction of the leakage flow with the main flow and resultant turning effects at the exit of the row have been investigated. The CFD method is based on a commercially available compressible Navier-Stokes solver (STAR-CD), using a turbulent compressible high Reynolds number k-ε model. Accurate numerical comparison of different blade tip geometries is achieved by using the same grid for the various shapes. The blocking strategy with O-grid structure is presented. The numerical results show clearly the beneficial effect of cutting away material from the pressure side. The higher surface curvature of the suction side squealer affects the pressure blade loading and increases the lift in the same way. This effect is increased by increasing the squealer height and results in a lower efficiency gain near the surge line. The best modification of the blade tip shows a maximum reduction of the tip discharge coefficient of 20 %. This leads to an improved total pressure ratio of 0.29% and an improved total polytropic efficiency of 0.40% under design condition. The influences of favourable squealer geometries on stage characteristics are described along an operating line. With a simulation of IGV-setting from Δα = −15° to Δα = +20° different operating points have been investigated in a swirl performance map. The beneficial effect of the suction side squealer found for the rotor row could assign to the stator row and results in an improved static pressure gain. Furthermore, design indications are presented which help to keep the efficiency gain under surge condition as high as possible.

Investigation on the effects of winglet geometry in a high loading compressor rotor

2021 ◽  
pp. 095765092110170
Author(s):  
Qingjun Zhao ◽  
Weiwei Cui ◽  
Wei Zhao ◽  
Xiaorong Xiang ◽  
Jianzhong Xu
Keyword(s):  
Flow Characteristics ◽  
Suction Side ◽  
Leakage Flow ◽  
Pressure Side ◽  
Low Velocity ◽  
Flow Area ◽  
Significant Deterioration ◽  
Maximum Width ◽  
Stall Margin ◽  
Blade Tip

The tip winglet is employed to improve the flow stability of NASA Rotor 37. Two suction-side winglets with the maximum width of 0.25 and 0.5 times of the width of local blade tip section and two pressure-side winglets with the maximum width of 0.5 and 0.9 times of the width of local blade tip section are designed and evaluated by numerical analysis of 3-D flowfield. The results show a rough leakage channel with two static pressure peaks over blade tip is formed due to the existing of pressure side winglet, and it benefits to reduce the effective through-flow area and massflow rate of leakage flow. The blocking effect on leakage flow weakens in new rotor with suction side winglet and it brings out the dramatical increase of leakage massflow rate and additional losses in tip region of rotor. With the comprehensive effects produced by tip winglet on leakage flow, the low-velocity region concerned on the interaction of leakage flow with passage shock has been reduced obviously in rotor with pressure side winglet and it leads to an over 11% increase of stall margin of transonic rotor with no penalty of efficiency. On the contrary, the suction side winglet contributes to a significant deterioration of tip flow characteristics of rotor with full expanded leakage flow and a smaller stall margin with over 17% decrease.

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