Stability Enhancement of a Multistage Compressor by Air Injection

Hiller, Sven-Jürgen; Matzgeller, Roland; Horn, Wolfgang

doi:10.1115/1.4001228

Cited by 17 publications

(13 citation statements)

References 11 publications

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“…Generally, the geometrical modification always works among the whole operating range for passive flow control methods, such as casing treatment, [19][20][21][22][23] blade tip modifications, [24][25][26][27] and blade tip winglet, [28][29][30] which may result in a reduction of performance near design point. While the active flow control can be imposed on the flow fields flexibly either all the time or only when the compressor's operating point moves dangerously close to the stall line, such as plasma actuation, [31][32][33] tip injection, [34][35][36][37][38] and aspiration/suction techniques. [39][40][41][42][43][44] At present, the researches about aspiration mainly focus on the control of the boundary layer separation on blade SS or the 3D separation in the hub corner, [45][46][47][48][49][50] and the results show that the performance of compressor cascade can be improved significantly by applying the suction method.…”

Section: Introductionmentioning

confidence: 99%

Effect of casing aspiration on the tip leakage flow in the axial flow compressor cascade

Mao

Liu

Tang

2017

Proceedings of the Institution of Mechanical Engineers, Part A:

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Tip leakage flow is usually responsible for the deterioration of compressor performance and stability. The current paper conducts numerical simulations on the impact of casing aspiration on the axial compressor cascade performance. Three aspiration schemes with different chordwise coverage are studied and analyzed. It is found that the cascade performance can be effectively improved by the appropriate casing aspiration, and the optimum aspiration scheme should cover the area including the onset point of tip leakage vortex and its vicinity. The control mechanisms are different for the aspiration schemes located at different blade chord ranges. For the aspiration scheme covering the onset point of tip leakage vortex, the improvement of the cascade performance is mainly due to that the starting point of the tip leakage vortex is shifted downstream. The original tip leakage vortex structure is divided into two parts if the aspiration scheme is located behind the onset point of tip leakage vortex and the final control effect is the combination of the influence from the two different parts of tip leakage vortex. Additionally, the casing aspiration redistributes the blade loading along the chord near blade tip. The results of these investigations may offer guidance for the appropriate design of aspiration scheme in the future updated compressors and the overall total pressure loss coefficient caused by aspiration slot should be considered in the design process.

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Section: Introductionmentioning

confidence: 99%

Effect of casing aspiration on the tip leakage flow in the axial flow compressor cascade

Mao

Liu

Tang

2017

Proceedings of the Institution of Mechanical Engineers, Part A:

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“…Indeed, numerous attempts have been made to develop tip flow control strategies. They have ranged from active methods, e.g., real-time control of the IGV stagger angle [24] and momentum injection into the casing endwall boundary layer upstream of the rotor [25,26] to passive techniques, such as endwall casing treatments [27,28]. Although it has been established that casing treatments do extend the stall margin, insufficient understanding of the flow mechanisms involved has hindered the ability to, for instance, optimize the location and geometry of grooves.…”

Section: Introductionmentioning

confidence: 99%

Visualization and Time-Resolved Particle Image Velocimetry Measurements of the Flow in the Tip Region of a Subsonic Compressor Rotor

Tan

Wilkes

et al. 2014

Journal of Turbomachinery

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A new optically index matched facility has been constructed to investigate tip flows in compressor-like settings. The blades of the one and a half stage compressor have the same geometry, but lower aspect ratio as the inlet guide vanes (IGVs) and the first stage of the low-speed axial compressor (LSAC) facility at NASA Glenn. With transparent blades and casings, the new setup enables unobstructed velocity measurements at any point within the tip region and is designed to facilitate direct measurements of effects of casing treatments on the flow structure. We start with a smooth endwall casing. High speed movies of cavitation and time-resolved PIV measurements have been used to characterize the location, trajectory, and behavior of the tip leakage vortex (TLV) for two flow rates, the lower one representing prestall conditions. Results of both methods show consistent trends. As the flow rate is reduced, TLV rollup occurs further upstream, and its initial orientation becomes more circumferential. At prestall conditions, the TLV is initially aligned slightly upstream of the rotor passage, and subsequently forced downstream. Within the passage, the TLV breaks up into a large number of vortex fragments, which occupy a broad area. Consequently, the cavitation in the TLV core disappears. With decreasing flow rate, this phenomenon becomes more abrupt, occurs further upstream, and the fragments occupy a larger area.

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“…A chocked injector was popular in supplying constant high-velocity jet in transonic compressor. 7,10 Khaleghi et al. 11 numerically proved that the maximum injection effectiveness was achieved when the injector was chocked.…”

Section: Introductionmentioning

confidence: 99%

“…Meanwhile, improving injection velocity was certified to be more efficient in enhancing compressor stability than widening injector size. 7…”

Section: Introductionmentioning

confidence: 99%

The effect of injector size on compressor performance in a transonic axial compressor with discrete tip injection

Wang

Chu

Zhang

2014

Proceedings of the Institution of Mechanical Engineers, Part A:

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The present study investigates the effects of injector size, which covers both circumferential extent and radial extent on compressor stability and radial work redistribution using time-accurate three-dimensional numerical simulations for multi-passages in a transonic compressor with discrete tip injection. Injector width ranges from 1% to 14.5% of casing perimeter and injector throat height varies from 2 to 6 times the height of rotor tip clearance. Six identical injectors are uniformly mounted around the annulus. Results indicate that, with sufficient covering of injection, tip injection can significantly improve compressor stability. Stability margin is improved by 3.5% employing 0.65% of the annulus mass flow. With injector width increased, stability improves sharply when the width is less than 4.5% of casing perimeter, but increases flatly for the rest coverage. Expanding injector throat height to an intermediate level can further enhance compressor stability, but excessive throat height is detrimental on account of the deterioration of the aerodynamic characteristic of Coanda injector. The average decrement of the blockage in injection region, which is defined as injection efficiency, is a key factor that takes primary responsibility for the capacity of tip injection in stability improvement. Injection efficiency derived from the same operating condition for all the configurations with tip injection is well-qualified to estimate the trend of stability improvement. The unsteady influence on radial work redistribution is much more significant than the time-averaged one.

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Stability Enhancement of a Multistage Compressor by Air Injection

Cited by 17 publications

References 11 publications

Effect of casing aspiration on the tip leakage flow in the axial flow compressor cascade

Effect of casing aspiration on the tip leakage flow in the axial flow compressor cascade

Visualization and Time-Resolved Particle Image Velocimetry Measurements of the Flow in the Tip Region of a Subsonic Compressor Rotor

The effect of injector size on compressor performance in a transonic axial compressor with discrete tip injection

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