Flow Mechanism for Stall Margin Improvement due to Circumferential Casing Grooves on Axial Compressors

Shabbir, Aamir; Adamczyk, John J.

doi:10.1115/1.2008970

Cited by 110 publications

(37 citation statements)

References 11 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Numerous techniques including stepped tip gaps and passive casing treatments such as circumferential grooves and skewed axial slots have been reported in open literature [5][6][7]. Such profiled wall treatments have usually benefited compressor stability at the cost of compressor efficiency.…”

Section: Introductionmentioning

confidence: 98%

Experimental Investigation of Tip Clearance Flow in a Transonic Compressor With and Without Plasma Actuators

Saddoughi

Bennett

Boespflug

et al. 2014

Journal of Turbomachinery

View full text Add to dashboard Cite

Blade tip losses represent a major performance penalty in low aspect ratio transonic compressors. This paper reports on the experimental evaluation of the impact of tip clearance with and without plasma actuator flow control on performance of an U.S. Air Force-designed low aspect ratio, high radius ratio single-stage transonic compressor rig. The detailed stage performance measurements without flow control at three clearance levels, classified as small, medium, and large, are presented. At design-speed, increasing the clearance from small to medium resulted in a stage peak efficiency drop of almost six points with another four point drop in efficiency with the large clearance (LC). Comparison of the speed lines at high-speed show significantly lower pressure rise with increasing tip clearance, the compressor losing 8% stall margin (SM) with medium clearance (MC) and an additional 1% with the LC. Comparison of the stage exit radial profiles of total pressure and adiabatic efficiency at both part-speed and design-speed and with throttling are presented. Tip clearance flow-control was investigated using dielectric barrier discharge (DBD) type plasma actuators. The plasma actuators were placed on the casing wall upstream of the rotor leading edge and the compressor mapped from part-speed to high-speed at three clearances with both axial and skewed configurations at six different frequency levels. The plasma actuators did not impact steady state performance. A maximum SM improvement of 4% was recorded in this test series. The LC configuration benefited the most with the plasma actuators. Increased voltage provided more SM improvement. Plasma actuator power requirements were almost halved going from continuous operation to pulsed plasma. Most of the improvement with the plasma actuators is attributed to the reduction in unsteadiness of the tip clearance vortex near-stall resulting in additional reduction in flow prior to stall.

show abstract

Section: Introductionmentioning

confidence: 98%

Experimental Investigation of Tip Clearance Flow in a Transonic Compressor With and Without Plasma Actuators

Saddoughi

Bennett

Boespflug

et al. 2014

Journal of Turbomachinery

View full text Add to dashboard Cite

show abstract

“…Thus, this is yet another proof that injecting fluid into the low-momentum tip flows, responsible for up to 30% of aerodynamic losses in axial compressors [51], will have an effect on compressor operational stability. If this effect is positive, the increase of axial momentum close to the tip can also have a positive impact on the stall margin of the downstream stages [75], [76] as well as the current stage.…”

Section: Change In the Axial Momentum Of Tip Flows Due To Water Injecmentioning

confidence: 99%

A Numerical Study of Water Injection on Transonic Compressor Rotor Performance

Szabó

2007

45th AIAA Aerospace Sciences Meeting and Exhibit

View full text Add to dashboard Cite

In this study, numerical simulations of two-phase flow in a transonic compressor rotor (NASA rotor 37) were performed. Both flow and droplets' governing equations were formulated and solved in the reference frame of the rotating blades. An Eulerian-Lagrangian approach was used for the continuous and discrete phases with a two-way interaction model to simulate the mass-, momentum-and energy exchange between the different phases. Water particles were injected at the inlet with uniform particle mass flux, fully evaporating inside the rotating blade row. The phase change was most intense in areas adjacent to shock waves, where the slip velocity of the droplets was the highest. Results show decreased circumferentially averaged total temperature ratio of the air-vapor mixture across the span, which is the direct result of inter-phase energy coupling. An entropy based approach to calculate the isentropic efficiency of a wet compression process in a transonic compressor rotor was also presented. Under the proposed method, the viscous dissipation function was calculated everywhere in the domain in the post-processing phase of the numerical simulation and integrated to the wall, with special treatment in the nearwall regions where high rates of entropy generation occur. For a water to air mass flow ratio of 1% results show increased entropy production across the span, resulting in a 5% drop in compressor isentropic efficiency. Analytical integration of wall functions and numerical integration of the viscous dissipation function allows for reasonable results even with relatively coarse grids and can also be applied for single-phase flows. A parametric study of the effect of initial particle parameters on the wet compression process was also performed. Several speedlines have been computed with different amounts of water, especially near the tip. Results show that numerical stall can be delayed with injection of water near the tip, due to the increase of the axial momentum of the fluid in the endwall region, which is the direct result of phase change.iv v ACKNOWLEDGEMENT

show abstract

“…The unsteadiness and shock motion were studied experimentally and numerically by Copenhaver et al [9], whose study indicated the presence of deterministic unsteadiness near the location of the shock. Some approaches to controlling the tip leakage flow and improving the compressor stability, known as casing treatment, used slots and grooves placed in the shroud over the tip of the blade [10][11][12][13]. Recirculation casing treatment employs a passageway to remove high-pressure fluid from downstream of the rotor leading or trailing edge and inject it upstream of the point of removal [14][15][16].…”

Section: Introductionmentioning

confidence: 99%

Parametric Study of Injection Angle Effects on Stability Enhancement of Transonic Axial Compressors

Khaleghi

Teixeira

Tousi

et al. 2008

Journal of Propulsion and Power

View full text Add to dashboard Cite

An effective approach in suppressing stall is mass injection upstream of the tip of an axial flow compressor. Developing reliable injection systems for high pressure ratio compressors requires an understanding of the effects of injection parameters, for example, injection angle, on the compressor stability and performance. This paper reports on a numerical investigation of injection angle on the operability of a high-speed compressor rotor. The injection port is set to be choked for all of the injection cases. Simulations indicate that injection angle has a significant impact on stability improvement. Maximum range extension is obtained when an injection yaw angle equal to 30 deg is applied. At this injection angle, the stalling mass flow coefficient was reduced by 17.4% by using an injected mass flow equivalent to 1.55% of the baseline annulus flow. Results also indicate that the best injection case creates an incidence angle of about 0 deg over the tip of the blade and adds the highest momentum in the relative frame of reference.Nomenclature A = area a = annulus adb = adiabatic amb = ambient DF = diffusion factor in = blade inlet j = jet out = blade outlet P 0 = total pressure rel = relative frame of reference T 0 = total temperature t = tip U, V = velocity x = axial component y = nondimensional wall distance = efficiency = tangential component = momentum = density = solidity = flow coefficient

show abstract

Flow Mechanism for Stall Margin Improvement due to Circumferential Casing Grooves on Axial Compressors

Cited by 110 publications

References 11 publications

Experimental Investigation of Tip Clearance Flow in a Transonic Compressor With and Without Plasma Actuators

Experimental Investigation of Tip Clearance Flow in a Transonic Compressor With and Without Plasma Actuators

A Numerical Study of Water Injection on Transonic Compressor Rotor Performance

Parametric Study of Injection Angle Effects on Stability Enhancement of Transonic Axial Compressors

Contact Info

Product

Resources

About