Rotating stalls in centrifugal impeller/vaned diffuser systems. 1st report, Experiment.

Yoshida, Yoshiki; Murakami, Yoshinori; Tsurusaki, Hiromu; Tsujimoto, Yoshinobu

doi:10.1299/kikaib.56.2991

Cited by 17 publications

(11 citation statements)

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“…Perhaps the most detailed study is the work done by Yoshida et al (1991) on a 7-bladed centrifugal impeller operating with a variety of diffusers, with and without vanes. Rotating stall with a single cell was observed in the impeller below certain critical flow coefficients, subject to the diffuser geometry.…”

Section: Rotating Stallmentioning

confidence: 99%

Vibration of Hydraulic Machinery

Wu¹,

Sheng-cai²,

Qian³

et al. 2013

Mechanisms and Machine Science

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Section: Rotating Stallmentioning

confidence: 99%

Vibration of Hydraulic Machinery

Wu¹,

Sheng-cai²,

Qian³

et al. 2013

Mechanisms and Machine Science

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“…The clearance between the impeller and the diffuser vanes is large. As this clearance decreases, the diffuser rotating stall tends to disappear [27]. The jet flow also occurs near the TE of the vane, and alternate jet flow and reverse flow appear when a rotating stall occurs, as shown in Figure 19.…”

Section: Propagation Mechanism Of a Rotating Stall As Seen Inmentioning

confidence: 93%

Dynamic Characteristics of Rotating Stall in Mixed Flow Pump

Yuan

Pan

et al. 2013

Journal of Applied Mathematics

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Rotating stall, a phenomenon that causes flow instabilities and pressure hysteresis by propagating at some fraction of the impeller rotational speed, can occur in centrifugal impellers, mixed impellers, radial diffusers, or axial diffusers. Despite considerable efforts devoted to the study of rotating stall in pumps, the mechanics of this phenomenon are not sufficiently understood. The propagation mechanism and onset of rotating stall are not only affected by inlet flow but also by outlet flow as well as the pressure gradient in the flow passage. As such, the complexity of these concepts is not covered by the classical explanation. To bridge this research gap, the current study investigated prerotation generated at the upstream of the impeller, leakage flow at the tip clearance between the casing and the impeller, and strong reserve flow at the inlet of the diffuser. Understanding these areas will clarify the origin of the positive slope of the head-flow performance curve for a mixed flow pump. Nonuniform pressure distribution and adverse pressure gradient were also introduced to evaluate the onset and development of rotating stall within the diffuser.

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“…6, 2008 simply extended toward the impeller outlet in order to restrict the secondary flow from hubto casing-sides. Yoshida et al (1991) experimentally study rotating stalls in centrifugal pump with a vaned diffuser. They reported that the diffuser rotating stall is suppressed by decreasing the number of vanes.…”

Section: Pump Primary Dimension Experimental Setup and Proceduresmentioning

confidence: 99%

On Improvement of Characteristic Instability and Internal Flow in Mixed Flow Pumps

Miyabe¹,

Furukawa

Maeda³

et al. 2008

JFST

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The difference of pump characteristics between two kinds of mixed flow pumps with low specific speed of 350 (min -1 , m 3 /min, m), which have the same impeller and the different diffuser vanes, is presented in the present paper. It was confirmed from the previous study that a diffuser rotating stall (DRS) occurs in the original type of mixed flow pump at about 65% flow rate of best efficiency point (BEP) and there is an abrupt drop of the total head characteristic. The relationship between pump characteristic instability and internal flow is investigated in detail by using a dynamic PIV measurement system (DPIV) and a commercial CFD code. As a result, the cause of characteristic instability is supposed for the original type as follows. The flow on the vaned diffuser hub-side becomes unstable due to adverse pressure gradient and strong backflow occurs at partial flow rate. Then it impinges against downstream flow from the impeller and the secondary flow from hub-to casing-sides occurs. This secondary flow blocks the downstream flow from the impeller and the inlet flow angle at the leading edge of adjacent diffuser vane decreases. Therefore, the flow separates on the suction surface of the adjacent diffuser vane inlet and a strong vortex is generated. After that, it develops and becomes a stall core. Next, the modified type of pump, where only diffuser vanes are modified, is tested. As a result, the flow rate, at which characteristic instability occurs, is shifted to lower one and the pump operating range becomes widened. It is clarified upon above considerations that the secondary flow has been restricted and diffuser performance has been improved in comparison with the original type.

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Rotating stalls in centrifugal impeller/vaned diffuser systems. 1st report, Experiment.

Cited by 17 publications

References 0 publications

Vibration of Hydraulic Machinery

Vibration of Hydraulic Machinery

Dynamic Characteristics of Rotating Stall in Mixed Flow Pump

On Improvement of Characteristic Instability and Internal Flow in Mixed Flow Pumps

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