Numerical Investigation of the Unsteady Flow Inside a Centrifugal Compressor Stage With Pipe Diffuser

Grates, Daniel; Jeschke, Peter; Niehuis, Reinhard

doi:10.1115/1.4024873

Cited by 15 publications

(14 citation statements)

References 6 publications

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“…This is an inherent feature in a centrifugal diffuser, and some previous studies prove the reality. Zachau (2008) draws a similar conclusion from the experimental results in his investigation on the pipe diffuser, and Grates et al (2014) present similar numerical and experimental results when investigating the static pressure distribution at the diffuser shroud. The increasing rate, however, cannot be too high, or the flow would suffer a great adverse static pressure gradient which exacerbates the instability of the flow field.…”

Section: Static Pressure Distribution Along Diffuser Passagesupporting

confidence: 52%

“…Pipe diffuser passages are made to intersect with adjacent ones and in this way the leading edges with elliptical ridges (Fig. 1) are formed (Kenny 1969, Zachau 2008, Grates et al 2014, Zachau et al 2009. At the same time, the beginning and the cusp (shown in Fig.…”

Section: Geometry Characteristicsmentioning

confidence: 99%

“…The vortex near the back wall is generated by the interaction between the flow passing over the ridges and the flow in the backflow area. More detailed perspective about the generation process of the pair vortices is presented by Grates et al (2014).…”

Section: Vortices and Total Pressure Distributionmentioning

confidence: 99%

“…Zachau (2008) studies the threedimensional flow phenomena with PIV technology, and results show that streamlines are pushed to the suction side (SS) of the passage and flow separation occurs in regions near the pressure side (PS). Grates et al (2014) reveal that the fluid flow inside impeller and pipe diffuser is highly unsteady. In the inlet domain, the leading edge of the pipe diffuser generates a pair of vortices, and it can help mix the non-uniform inlet flow better (Zachau 2008, Gates et al 2014, and Zachau et al 2009).…”

Section: Introductionmentioning

confidence: 99%

“…In the inlet domain, the leading edge of the pipe diffuser generates a pair of vortices, and it can help mix the non-uniform inlet flow better (Zachau 2008, Gates et al 2014, and Zachau et al 2009). Grates et al (2014) also investigate the generation process of the vortices by unsteady CFD and notices that the intensity of the vortex near impeller hub is constant in time while the other one is oscillating.…”

Section: Introductionmentioning

confidence: 99%

See 4 more Smart Citations

Flow Characteristics of a Pipe Diffuser for Centrifugal Compressors

Sun¹,

Zheng²,

Linghu³

2017

JAFM

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The pipe diffuser, an efficient kind of radial bladed diffuser, is widely used in centrifugal compressors for gas turbine engines. This paper investigates flow characteristics of a pipe diffuser for centrifugal compressors by solving three-dimensional Reynolds-averaged Navier-Stokes equations. The results show that the pipe diffuser is adaptable to high Mach number incoming flows, and its unique leading edge could uniform the flow distortion. Numerical analysis indicates that the choke in pipe diffuser occurs suddenly, which leads to the dramatically steep performance curves near choke condition. Besides, it is found that the first half flow passage is particularly important to the pipe diffuser performance as it influences the choking behavior, the static pressure distribution, and the matching, so more attention should be paid to this region when designing or optimizing a pipe diffuser. Two counter-rotating vortices generated in the diffuser inlet region are captured by numerical simulation, and they can exist in the downstream of the diffuser passage. More detailed analysis show that these two vortices dominate the flow structure in the whole diffuser passage by shifting flow to certain positions and forming high-momentum flow cells and wake flow cells. The leading edge formed by the intersection of adjacent diffuser passages significantly affects this pair of vortices. In addition, these two vortices also affect the flow separation in pipe diffuser flow passages, they suppress separation near the front wall and back wall while facilitate separation at center locations. Therefore, it is recommended to design the leading edge of the pipe diffuser carefully to control the vortices and obtain a better flow field.

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Section: Static Pressure Distribution Along Diffuser Passagesupporting

confidence: 52%