Suppression of Performance Curve Instability of an Axial‐Flow Pump by Using a Double‐Inlet‐Nozzle

Flores, P. Pérez; Kosyna, G.; Wulff, Detlev

doi:10.1155/2008/536850

Cited by 9 publications

(3 citation statements)

References 4 publications

(6 reference statements)

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“…A similar effect is reported by Perez et al. 10 in taking measurements at the same test rig with a double-inlet nozzle in front of the rotor instead of the casing grooves. The double-inlet nozzle separates the spinning backflow and the non-spinning main flow and, hence, has a similarly positive effect on pump head and efficiency.…”

Section: Discussionsupporting

confidence: 81%

Eliminating the head instability of an axial-flow pump using axial grooves

Goltz

Kosyna

Delgado

2012

Proceedings of the Institution of Mechanical Engineers, Part A:

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This article presents a new type of casing treatment which completely eliminates the drop in the head characteristic of a single-stage, axial-flow pump without any noticeable negative effect on the pump efficiency. The casing treatment consists of 60 shallow axial grooves, which are located only in front of the rotor. These shallow axial grooves differ from other commonly investigated types of casing treatments with respect to their mechanism of action. For a qualitative as well as a quantitative analysis of the mechanism of action of grooves, oil flow pictures were taken and also radial velocity profiles were measured using calibrated pressure probes. These investigations reveal that, unlike other types of casing treatments, the grooves do not delay the onset of stall by controlling the rotor inflow before reaching the stall point. However, when stall occurs, the shallow axial grooves reduce the detrimental swirl component of the stall cell, which otherwise leads to the drop in pump head at the stall point. The pump efficiency at design is not affected by these types of grooves. In deep stall, the efficiency is even higher for the grooved casing due to better inlet flow conditions.

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Section: Discussionsupporting

confidence: 81%

Eliminating the head instability of an axial-flow pump using axial grooves

Goltz

Kosyna

Delgado

2012

Proceedings of the Institution of Mechanical Engineers, Part A:

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“…Similarly, axial-flow pumps, widely used for water transfer and supply, can also encounter this problem during operation [14][15][16][17][18][19]. The saddle-shaped unstable region should be avoided as it can result in internal flow disturbance, intensification of hydraulic vibration, and a sharp decline in efficiency [20][21][22][23]. Therefore, it is crucial to study the critical state of the saddle-shaped unstable region and develop objective criteria for identifying this state.…”

Section: Introductionmentioning

confidence: 99%

Critical State Calculation of Saddle-Shaped Unstable Region of the Axial-Flow Pump Based on Bifurcation SST k–ω Model

Pang

Huang

Yan

et al. 2023

JMSE

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This study aims to investigate the critical state of the saddle-shaped unstable region of the axial-flow pump and propose a suitable criterion for identifying this state. The bifurcation SST k–ω model considered the rotation effect is used in the present work and verified in the numerical calculation of a water jet pump. Then, it is used to simulate the critical state of the axial-flow pump. Results show that the leading-edge separation vortex generates at 0.6Qd, while the head declines only at 0.55Qd. Therefore, using the inflection point of the head-flow curve as the critical state criterion is unsuitable. In addition, the fixed monitoring point is unsuitable for identifying the critical state due to the insensitivity to the amplitude, main frequency, and periodicity changes at the critical state. Finally, to identify the critical state, it is essential to arrange a monitoring point at the leading edge of the blade suction near the shroud, which should rotate with the impeller. The critical state criterion is that the main frequency position of the pressure fluctuation signal is offset at the monitoring point, and the amplitude is increased by 10 times.

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“…Even though the use of casing treatments could provide good improvement of compressor stability, it also has unavoidable side effects such as efficiency loss and additional weight for modified configurations (Fujita and Takata, 1984;Pérez Flores et al, 2008;Weichert et al, 2011). Therefore, the slotted rotor would be selected in this work.…”

Section: Introductionmentioning

confidence: 99%

Numerical Investigation on the Performance of Transonic Axial Compressor with Naturally Aspirated Slots on Blade

Aksorn-In¹,

Chen²,

Zhao³

et al. 2019

Proceedings of Global Power &Amp; Propulsion Society

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The stable operating range is one of the key performance parameters on safety for general compressors. In order to improve the stable range, the flow control technique by slotted rotor was computationally studied and investigated based on the case of well-known transonic axial compressor (NASA Rotor 67). The principle of slotted blade is that the rotor blade is manufactured with the aim to have a slot (connecting between pressure side and suction side) at designed location. Then, the fluid is able to flow from pressure side to suction side by the pressure differences. This effect could literally energize the mainstream flow including the retarded flow caused by the aerodynamic losses. As a result, the operating range of compressor would be improved. Throughout this work, the action mechanism of the slot and the impact on compressor performance were analyzed by the prominent commercial software, NUMECA/EURANUS. The slot was located at three significant areas (e.g., leading edge, midchord, and trailing edge). Moreover, it was also located relative to the axial tip chord of the rotor blade. The stability improvement and the modified performance of the investigated compressor (e.g., pressure ratio and efficiency) were evaluated and compared with those of original blade. The location of slot giving the best improvement was finally identified. Afterwards, the optimum location would be selected for the further investigation by orienting the slot to be inclined configuration. In addition, the geometry of slot would be changed to nozzle as well for high velocity flow at the exit in order to gain more energization (more improvement).

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Suppression of Performance Curve Instability of an Axial‐Flow Pump by Using a Double‐Inlet‐Nozzle

Cited by 9 publications

References 4 publications

Eliminating the head instability of an axial-flow pump using axial grooves

Eliminating the head instability of an axial-flow pump using axial grooves

Critical State Calculation of Saddle-Shaped Unstable Region of the Axial-Flow Pump Based on Bifurcation SST k–ω Model

Numerical Investigation on the Performance of Transonic Axial Compressor with Naturally Aspirated Slots on Blade

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