A Numerical Investigation of Boundary Layer Suction in Compound Lean Compressor Cascades

2005 ◽  
Vol 128 (2) ◽  
pp. 357-366 ◽  
Author(s):  
Yanping Song ◽  
Fu Chen ◽  
Jun Yang ◽  
Zhongqi Wang
Keyword(s):  
Boundary Layer ◽  
Numerical Investigation ◽  
Numerical Study ◽  
Pressure Rise ◽  
Total Loss ◽  
Compressor Cascade ◽  
Suction Surface ◽  
Flow Rates ◽  
Boundary Layer Suction ◽  
Suction Flow

This paper is focused on the numerical investigation of boundary layer suction (BLS) via a slot on the suction surfaces of two compound lean compressor cascades with large camber angles as well as a conventional straight compressor cascade for comparison. The objective of the investigation is to study the influence of boundary layer suction on the performance of compound lean compressor cascades, thus to discuss the possibility of the application of boundary layer suction to improve their performance. An extensive numerical study has been carried out under different spanwise lengths, different axial positions of the slots, and different suction flow rates. The results show that the total loss of all three cascades is reduced significantly by boundary layer suction, and the largest reduction occurs at the highest suction flow rate. The axial locations of the slot have little effect on the total loss of the three cascades, which means the slots are opened within the optimal axial range in this case. The slot opened along the full span is the best one to obtain the largest reduction in total loss for all three cascades due to the alleviation of flow separation in the corner between the endwall and the suction surface. Moreover, the flow turning is increased, and pressure rise at the rear of the passage is recovered along the whole blade height via boundary layer suction along the full span, enhancing the working range of the highly loaded compressor cascades.

A Numerical Investigation of Boundary Layer Suction in Compound Lean Compressor Cascades

2005 ◽  
Author(s):  
Yanping Song ◽  
Fu Chen ◽  
Jun Yang ◽  
Zhongqi Wang
Keyword(s):  
Boundary Layer ◽  
Numerical Investigation ◽  
Numerical Study ◽  
Pressure Rise ◽  
Total Loss ◽  
Compressor Cascade ◽  
Suction Surface ◽  
Flow Rates ◽  
Boundary Layer Suction ◽  
Suction Flow

This paper is focused on the numerical investigation of boundary layer suction (BLS) via a slot on the suction surfaces of two compound lean compressor cascades with large camber angles as well as a conventional straight compressor cascade for comparison. The objective of the investigation is to study the influence of boundary layer suction on the performance of compound lean compressor cascades, thus to discuss the possibility of the application of boundary layer suction to improve their performance. An extensive numerical study has been carried out under different spanwise lengths and different axial positions of the slots, and different suction flow rates. The results show that the total loss of all three cascades is reduced significantly by boundary layer suction, and the largest reduction occurs at the highest suction flow rate. The axial locations of the slot have little effect on the total loss of the three cascades, which means the slots are opened within the optimal axial range in this case. The slot opened along the full span is the best one to obtain the largest reduction in total loss for all three cascades due to the alleviation of flow separation in the corner between the endwall and the suction surface. Moreover, the flow turning is increased, and pressure rise at the rear of the passage is recovered along the whole blade height via boundary layer suction along the full span, enhancing the working range of the highly loaded compressor cascades.

Effect of Boundary Layer Suction on the Corner Separation in a Highly Loaded Axial Compressor Cascade

2020 ◽  
Author(s):  
Tian Liang ◽  
Bo Liu ◽  
Stephen Spence
Keyword(s):  
Boundary Layer ◽  
Axial Compressor ◽  
Compressor Cascade ◽  
Flow Uniformity ◽  
Suction Surface ◽  
Flow Rates ◽  
Corner Separation ◽  
Boundary Layer Suction ◽  
End Wall ◽  
Suction Flow

Abstract Control of corner separation in axial compressor blade rows has attracted much interest due to its potential to improve compressor efficiency and the energy utilization in turbomachinery. This paper investigates the effectiveness and mechanisms of boundary layer suction in controlling the corner separation of a highly loaded axial compressor cascade. Numerical simulations have been carried out to investigate the effect of different suction schemes on the loss downstream of the cascade and the change in incidence characteristics with the variation of the suction flow rate. The results show that the effectiveness of flow suction in controlling the flow separation depends heavily on the proportion of the blade for which it is applied. It was found that suction along part of the blade span on the suction surface could effectively remove the separation at the region of the span influenced by the suction slot. However, this resulted in a deterioration of the flow field at other parts of the span. The full span suction scheme on the suction surface not only eliminated the separation of the boundary layer in the middle of the blade, but also significantly improved the flow uniformity near the end-wall. Despite the improvement in flow uniformity using the full-span suction scheme, a three-dimensional (3D) corner separation still existed due to the strong cross-passage pressure gradient. To improve the flow field uniformity further, two combined suction schemes with one spanwise slot on the suction surface and another slot on the end-wall were designed in order to fully remove both the separated flow on the blade suction surface and the 3D corner separation. It was found that the total pressure loss coefficient was reduced significantly by 63.8% with suction flow rates of 1.88% and 0.82% for the slots on the suction surface and the end-wall respectively. Further work showed that the behavior of the loss coefficient is different as the combination of suction flow rates is changed for different incidence. The cascade loss at high incidence operation can be more effectively reduced with suction control on the end-wall. When implementing combined suction, it is necessary to determine the best combination of suction flow rate according to the incidence level.

Effects of Boundary Layer Suction on the Performance of Compressor Cascades

2006 ◽  
Author(s):  
Fu Chen ◽  
Yanping Song ◽  
Huanlong Chen ◽  
Zhongqi Wang
Keyword(s):  
Boundary Layer ◽  
Flow Rate ◽  
Flow Behavior ◽  
Aerodynamic Performance ◽  
Compressor Cascade ◽  
Suction Surface ◽  
Boundary Layer Suction ◽  
Suction Flow ◽  
Suction Slot ◽  
Highly Loaded

The effects of boundary layer suction on the aerodynamic performance of compressor cascade are mainly determined by: (1) the location of the suction slot; (2) the suction flow rate; (3) the suction slot geometry; and (4) the aerodynamic parameters of the cascade (e.g. solidity and incidence). In this paper, an extensive numerical study has been carried out to investigate the effects of these influencing factors in a highly-loaded compressor cascade by comparing the aerodynamic performance of the cascade in order to give guidance for the application of boundary layer suction to improve the performance of modern highly-loaded compressors. The results show that boundary layer suction alleviates the accumulation of low-energy fluid at suction surface corners and enhances the ability of flow turning, and this improvement in flow behavior depends on the location of the suction slot and the suction flow rate. When the location of the suction slot and the suction flow rate are fixed, as the cascade solidity decreases from 1.819 to 1.364 and 1.091, the cascade total pressure loss is reduced at most by 25.1%, 27.7% and 32.9% respectively, and the cascade exit flow deviation is decreased by 3.1°, 4.2° and 5.0° accordingly. Moreover, boundary layer suction also has the largest effect in the cascade with smaller solidity at large positive incidences, which means that boundary layer suction is an effective way to widen the stable operating range of the highly-loaded compressor cascade. The suction slot geometry is described by the suction slot width and the suction slot angle with respect to the direction normal to the blade suction surface. The results show that the flow behavior is improved and the endwall loss is reduced further as the increase of the suction slot width. The suction slot angle has an obvious influence on the pressure inside the slot, therefore, should be considered in the design of the suction slot since the maximum pressure inside the slot is usually required.

Control of Three-Dimensional Separations in Axial Compressors by Tailored Boundary Layer Suction

2007 ◽  
Vol 130 (1) ◽  
Author(s):  
Semiu A. Gbadebo ◽  
Nicholas A. Cumpsty ◽  
Tom P. Hynes
Keyword(s):  
Boundary Layer ◽  
Static Pressure ◽  
Three Dimensional ◽  
Pressure Rise ◽  
Surface Flow ◽  
Compressor Cascade ◽  
Suction Surface ◽  
Blade Passage ◽  
Boundary Layer Suction ◽  
End Wall

One of the important ways of improving turbomachinery compressor performance is to control three-dimensional (3D) separations, which form over the suction surface and end wall corner of the blade passage. Based on the insights gained into the formation of these separations, this paper illustrates how an appropriately applied boundary layer suction of up to 0.7% of inlet mass flow can control and eliminate typical compressor stator hub corner 3D separation over a range of operating incidence. The paper describes, using computational fluid dynamics, the application of suction on the blade suction surface and end wall boundary layers and exemplifies the influence of end wall dividing streamline in initiating 3D separation in the blade passage. The removal of the separated region from the blade suction surface is confirmed by an experimental investigation in a compressor cascade involving surface flow visualization, surface static pressure, and exit loss measurements. The ensuing passage flow field is characterized by increased blade loading (static pressure difference between pressure and suction surface), enhanced average static pressure rise, significant loss removal, and a uniform exit flow. This result also enables the contribution of the 3D separation to the overall loss and passage blockage to be assessed.

Location Effect of Boundary Layer Suction on Compressor Hub-Corner Separation

2014 ◽  
Author(s):  
Ping-Ping Chen ◽  
Wei-Yang Qiao ◽  
Karsten Liesner ◽  
Robert Meyer
Keyword(s):  
Boundary Layer ◽  
Pressure Loss ◽  
Total Pressure ◽  
Three Dimensional ◽  
Base Flow ◽  
Total Pressure Loss ◽  
Compressor Cascade ◽  
Suction Surface ◽  
Corner Separation ◽  
Boundary Layer Suction

The large secondary flow area in the compressor hub-corner region usually leads to three-dimensional separation in the passage with large amounts of total pressure loss. In this paper numerical simulations of a linear high-speed compressor cascade, consisting of five NACA 65-K48 stator profiles, were performed to analyze the flow mechanism of hub-corner separation for the base flow. Experimental validation is used to verify the numerical results. Active control of the hub-corner separation was investigated by using boundary layer suction. The influence of the selected locations of the endwall suction slot was investigated in an effort to quantify the gains of the compressor cascade performance. The results show that the optimal chordwise location should contain the development section of the three-dimensional corner separation downstream of the 3D corner separation onset. The best pitchwise location should be close enough to the vanes’ suction surface. Therefore the optimal endwall suction location is the MTE slot, the one from 50% to 75% chord at the hub, close to the blade suction surface. By use of the MTE slot with 1% suction flow ratio, the total-pressure loss is substantially decreased by about 15.2% in the CFD calculations and 9.7% in the measurement at the design operating condition.

scholarly journals Flow control in linear compressor cascades by inclusion of suction side dimples at varying locations

2018 ◽  
Vol 232 (6) ◽  
pp. 706-721 ◽  
Author(s):  
Hua-wei Lu ◽  
Yi Yang ◽  
Shang Guo ◽  
Yu-xuan Huang ◽  
Hong Wang ◽  
...  
Keyword(s):  
Boundary Layer ◽  
Separation Bubble ◽  
Pressure Rise ◽  
Suction Side ◽  
Aerodynamic Performance ◽  
Chord Length ◽  
Compressor Cascade ◽  
Suction Surface ◽  
Linear Compressor ◽  
Comparison Results

The flow characteristics and loss behavior over an array of parallel recessed dimples on a high turning linear compressor cascade have been investigated using the Reynolds-averaged Navier–Stokes approach. Steady simulations have been carried out at three dimple locations of 10–32%, 38–60%, 60–82% chord length of suction surface with the inlet Mach number of 0.7. Flow conditions were compared in exit loss coefficient, static pressure rise, streamline patterns, vortex structures, boundary layer parameters, and blade surface pressure between the smooth and the modified cascades. The results indicate that the dimples prior to the separation line report an overall enhancement in the aerodynamic performance in comparison to that of a smooth blade. Symmetric spanwise vortex, which energizes the boundary layer, can roll up inside the dimples. Therefore, the boundary layer with the higher momentum can bear the adverse pressure gradient, which will suppress the flow separation and associated losses. Three dimpled configurations can all eliminate the separation bubble on the suction side, but the dimples located at 60–82% chord length take the negative effect on the aerodynamic performance due to the more chaos condition in the corner separation region. The comparison results also indicate that the optimum location of dimples may exist in front of the separation bubble. Loss reduction of 18.8% and 10.8% can be achieved under the 10–32% c and 38–60% c dimple configurations, respectively.

Numerical Study on End-Wall Flow in Highly Loaded Supercritical Compressor Cascades

2009 ◽  
Author(s):  
Bin Jiang ◽  
Songtao Wang ◽  
Guotai Feng ◽  
Zhongqi Wang
Keyword(s):  
Boundary Layer ◽  
Flow Separation ◽  
Numerical Study ◽  
Thickness Distribution ◽  
Flow Conditions ◽  
Compressor Cascade ◽  
Suction Surface ◽  
Flow Phenomena ◽  
Wall Flow ◽  
End Wall

This paper presents a numerical study on three-dimensional flow phenomena near the endwall of a linear high-turning compressor cascade at supercritical flow conditions. The compressor cascade with 60° camber angle was designed at a higher supercritical speed (M1>0.9) by optimum method based on the baseline which aimed at improving the flow near the stator hub of small transonic fans. The camber line and thickness distribution curves of the baseline are formed by quadratic polynomials and double cubic curves respectively. The stack line and the thickness distribution near the end-wall were chosen as optimization variables to approach the objective function of total pressure loss coefficient, since they are the two main geometry parameters which can influence end-wall flow obviously. The analysis in current paper focuses on comparing the flow phenomena near the end-wall of baseline cascade with that of optimized one. Numerical simulation results are presented to show the loss reduction from the baseline to the optimized cascade near end-wall. The boundary-layer development on the suction surface, flow separation structure, shockwave and local supersonic area on the suction surface near the end-wall are analyzed in detail. The optimized cascade has a stronger shockwave near the leading edge. It was found that the radial flow of the boundary-layer caused by the optimization of stack line is the key factor influencing the aerodynamics loss near the end-wall at supercritical condition which also plays an important part in second-flow and flow separation in the corner. An understanding of the low-loss pattern of the end-wall flow and the flow filed structure for high-turning compressor at higher supercritical flow conditions then is summarized at the end of this paper.

The Cost of Flow Control in a Compressor

2011 ◽  
Author(s):  
Simon W. Evans ◽  
Howard P. Hodson
Keyword(s):  
Boundary Layer ◽  
Flow Control ◽  
Vortex Generator ◽  
Control Methods ◽  
Compressor Cascade ◽  
Suction Surface ◽  
Boundary Layer Suction ◽  
Blade Row ◽  
Efficiency Increase ◽  
The Cost

This paper documents an analysis performed to estimate the cycle cost of flow control in a compressor. The analysis is based on a series of experiments conducted in a low-speed compressor cascade at high incidence. In these experiments, flow control was applied to delay a turbulent separation on the suction surfaces of the blades in the cascade. The flow control methods studied include boundary layer suction and both steady and pulsed vortex generator jets. Endwall control was also applied to remove corner separations. Tip gaps and endwall suction were both studied for this purpose. The flow control methods studied were able to successfully delay a separation occurring on the suction surface of the blades, reducing the loss coefficient. The mass flow rates and jet supply pressures required to achieve control in each case were used to model a single flow-controlled blade row in a typical turbofan cycle using cycle analysis software. The cost of control to the cycle was calculated as the polytropic compressor efficiency increase required to maintain thrust relative to a conventional cycle with no flow control. The results of the analysis show that the benefits of flow control significantly outweigh the cost. They also show that boundary layer suction coupled with endwall suction yields the lowest cycle cost. This is because of the small pressure difference required to drive suction, which allows reinjection of the aspirated air a short distance upstream of the flow controlled blade row.

Shock train control by boundary layer suction in a scramjet isolator

2020 ◽  
pp. 095441002096753
Author(s):  
Vignesh Ram Petha Sethuraman ◽  
Tae Ho Kim ◽  
Heuy Dong Kim
Keyword(s):  
Boundary Layer ◽  
Flow Field ◽  
Pressure Ratio ◽  
Critical Role ◽  
Pressure Rise ◽  
Flow Ratio ◽  
Shock Train ◽  
Boundary Layer Suction ◽  
Scramjet Engine ◽  
Suction Flow

The isolator plays a critical role in the scramjet engine situated between the inlet and the combustion chamber. The flow field is more complex with shock–shock interaction and shock boundary layer interaction result in a series of compression waves reffered to as “shock train”. The presence of such flow inside the isolator can degrade the performance of the scramjet engine. The present study focus on the characteristic of the shock train flow field in an isolator and its control by partial removal of the boundary layer. The results examine the variation of the inlet to outlet pressure ratio along with different suction flow ratio. Numerical results indicate that boundary layer suction will cause the slight downstream movement of shock train location and the length of the shock train is reduced. Also when the suction flow gets choked, the transformation of shock train into a single curved normal shock is observed. The effect of varying the upstream boundary layer plays a major role in the suction flow ratio. Furthermore, a significant improvement in the total pressure loss and static pressure rise is obtained by boundary layer suction. The location of the shock train has a greater impact on the performance of the isolator.

Control of Flow Separations in Compressor Cascade by Boundary Layer Suction Holes in Suction Surface

2013 ◽  
Author(s):  
Jun Ding ◽  
Shaowen Chen ◽  
Hao Xu ◽  
Shijun Sun ◽  
Songtao Wang
Keyword(s):  
Boundary Layer ◽  
Experimental Investigation ◽  
Flow Separation ◽  
Load Capacity ◽  
Leading Edge ◽  
Control Flow ◽  
Compressor Cascade ◽  
Suction Surface ◽  
Boundary Layer Suction ◽  
Aerodynamic Parameters

Boundary layer suction is used in turbomachinery to control flow separation to enhance the loading capacity of a compressor. This paper focuses on both numerical calculation and experimental investigation with boundary layer suction holes made in the suction surface of a compressor cascade with a large camber angle. Experimental and numerical investigations are carried out with suction holes in different positions. In the experimental investigation, exit aerodynamic parameters are measured using a five-hole aerodynamic probe, and ink-trace flow visualization is adopted on cascade surface. Experimental and numerical results indicate that both side and middle suctions on the suction surface can efficiently remove low-energy fluid to increase the cascade load capacity while they effectively restrain the corner flow separation. The cascade aerodynamic performance is obviously improved by middle and side suctions, and it is also significantly altered by the position of suction changes. The middle suction holes have their best positions at about 60–66% chord length from the leading edge, and the side suction holes have their best positions a little downstream the corner separation line.

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