scholarly journals Internal Flow of a High Specific-Speed Diagonal-Flow Fan (Rotor Outlet Flow Fields with Rotating Stall)

2003 ◽  
Vol 9 (5) ◽  
pp. 337-344 ◽  
Author(s):  
Norimasa Shiomi ◽  
Wen-Xin Cai ◽  
Akio Muraoka ◽  
Kenji Kaneko ◽  
Toshiaki Setoguchi
Keyword(s):  
Internal Flow ◽  
Flow Fields ◽  
Rotating Stall ◽  
Outlet Flow ◽  
Specific Speed

scholarly journals Internal Flow of a High Specific-Speed Diagonal-Flow Fan (Rotor Outlet Flow Fields with Rotating Stall)

2003 ◽  
Vol 9 (5) ◽  
pp. 337-344 ◽  
Author(s):  
Norimasa Shiomi ◽  
Wen-Xin Cai ◽  
Akio Muraoka ◽  
Kenji Kaneko ◽  
Toshiaki Setoguchi
Keyword(s):  
Flow Field ◽  
Three Dimensional ◽  
Internal Flow ◽  
Flow Fields ◽  
Rotating Stall ◽  
Rotor Blades ◽  
Rotor Speed ◽  
Double Phase ◽  
Outlet Flow ◽  
Specific Speed

We carried out investigations for the purpose of clarifying the rotor outlet flow fields with rotating stall cell in a diagonal-flow fan. The test fan was a high–specific-speed (ns=1620) type of diagonal-flow fan that had 6 rotor blades and 11 stator blades. It has been shown that the number of the stall cell is 1, and its propagating speed is approximately 80% of its rotor speed, although little has been known about the behavior of the stall cell because a flow field with a rotating stall cell is essentially unsteady. In order to capture the behavior of the stall cell at the rotor outlet flow fields, hot-wire surveys were performed using a single-slant hotwire probe. The data obtained by these surveys were processed by means of a double phase-locked averaging technique, which enabled us to capture the flow field with the rotating stall cell in the reference coordinate system fixed to the rotor. As a result, time-dependent ensemble averages of the three-dimensional velocity components at the rotor outlet flow fields were obtained. The behavior of the stall cell was shown for each velocity component, and the flow patterns on the meridional planes were illustrated.

Unsteady Flow in the Vaned Diffuser of a Low Specific Speed Centrifugal Pump With an Unshrouded Impeller

2019 ◽  
Author(s):  
Asuma Ichinose ◽  
Tomoki Takeda ◽  
Kazuyoshi Miyagawa ◽  
Yohei Ogawa ◽  
Hideyo Negishi ◽  
...  
Keyword(s):  
Centrifugal Pump ◽  
Internal Flow ◽  
The Other ◽  
Vaned Diffuser ◽  
Design Point ◽  
Other Hand ◽  
Impeller Outlet ◽  
Outlet Flow ◽  
Low Specific Speed ◽  
Specific Speed

Abstract The unsteady internal flow in a low specific speed centrifugal pump was experimentally and numerically investigated. Unshrouded impellers enable high head designs but on the other hand, they exhibit complicated internal flow and an efficiency decline compared to shrouded impellers. Furthermore, the complicated impeller outlet flow induces unsteady internal flow in the vaned diffuser. Therefore, a detailed investigation of the internal flow is required in order to increase the efficiency of these low specific speed centrifugal pumps. The aims of this paper are to clarify the loss mechanisms in the impeller and to investigate the effect of impeller outlet flow to the diffuser internal flow at the design point. The detailed pump internal flow is investigated using unsteady computation, which enables the computation of the 3D flow pattern. The reversed flow and the secondary flow are induced by the tip leakage flow, and this creates a high loss region in the blade-to-blade region. On the other hand, the mixing effect is remarkable at the impeller outlet, and this affects the creation of the wake. This flow behavior makes the internal flow of the diffuser unsteady and the diffuser performance fluctuates due to the impeller wake at the design point.

Effects of Flow Path Height of Impeller Exit and Diffuser on Flow Fields in a Transonic Centrifugal Compressor

2015 ◽  
Author(s):  
Isao Tomita ◽  
Seiichi Ibaraki ◽  
Koji Wakashima ◽  
Masato Furukawa ◽  
Kazutoyo Yamada ◽  
...  
Keyword(s):  
Centrifugal Compressor ◽  
High Efficiency ◽  
Pressure Ratio ◽  
Internal Flow ◽  
Flow Fields ◽  
Flow Path ◽  
Rotating Stall ◽  
Low Carbon ◽  
Detached Eddy Simulation ◽  
Transonic Centrifugal Compressor

Today turbocharging has become a fundamental technology to realize engine downsizing, which is an attractive strategy for low carbon emissions. High efficiency and wide operating range are strongly required for the automotive turbochargers. Especially centrifugal compressors for automotive turbochargers are requested to operate with high efficiency from the surge limit to the choke limit. The internal flow in a centrifugal compressor is however three dimensional and shows very complex unsteady flow phenomena like a rotating stall and a surging, which have yet to be elucidated fully. In this study the effect of flow path height of impeller and diffuser on flow fields in a transonic centrifugal compressor has been investigated both numerically and experimentally. Detached Eddy Simulation (DES) has been applied and revealed the reduction of impeller exit flow path affects the accumulation of low momentum flow at impeller inlet as well as impeller exit. Also it has been confirmed experimentally the 15% reduction of the impeller exit flow path height can halve the surging flow rate with same choking capacity at pressure ratio of 2.6.

scholarly journals Optimal Design of Slit Impeller for Low Specific Speed Centrifugal Pump Based on Orthogonal Test

2021 ◽  
Vol 9 (2) ◽  
pp. 121
Author(s):  
Yang Yang ◽  
Ling Zhou ◽  
Hongtao Zhou ◽  
Wanning Lv ◽  
Jian Wang ◽  
...  
Keyword(s):  
Numerical Simulation ◽  
Centrifugal Pump ◽  
Large Scale ◽  
Internal Flow ◽  
Orthogonal Test ◽  
Centrifugal Pumps ◽  
Initial Model ◽  
Low Specific Speed ◽  
Specific Speed ◽  
Four Levels

Marine centrifugal pumps are mostly used on board ship, for transferring liquid from one point to another. Based on the combination of orthogonal testing and numerical simulation, this paper optimizes the structure of a drainage trough for a typical low-specific speed centrifugal pump, determines the priority of the various geometric factors of the drainage trough on the pump performance, and obtains the optimal impeller drainage trough scheme. The influence of drainage tank structure on the internal flow of a low-specific speed centrifugal pump is also analyzed. First, based on the experimental validation of the initial model, it is determined that the numerical simulation method used in this paper is highly accurate in predicting the performance of low-specific speed centrifugal pumps. Secondly, based on the three factors and four levels of the impeller drainage trough in the orthogonal test, the orthogonal test plan is determined and the orthogonal test results are analyzed. This work found that slit diameter and slit width have a large impact on the performance of low-specific speed centrifugal pumps, while long and short vane lap lengths have less impact. Finally, we compared the internal flow distribution between the initial model and the optimized model, and found that the slit structure could effectively reduce the pressure difference between the suction side and the pressure side of the blade. By weakening the large-scale vortex in the flow path and reducing the hydraulic losses, the drainage trough impellers obtained based on orthogonal tests can significantly improve the hydraulic efficiency of low-specific speed centrifugal pumps.

Part Load Instability and Rotating Stall in a Multistage Low Specific Speed Pump

2021 ◽  
Author(s):  
Erik Vermunt ◽  
Martijn Van Der Schoot ◽  
Bruurs Bruurs ◽  
Bart Van Esch
Keyword(s):  
Rotating Stall ◽  
Part Load ◽  
Low Specific Speed ◽  
Specific Speed

scholarly journals Influence of guide vane clearance on internal flow of medium-specific speed Francis turbine

2019 ◽  
Vol 240 ◽  
pp. 022056
Author(s):  
Gnanasekaran Kishor Kumar ◽  
Tadachika Tanaka ◽  
Naoki Yamaguchi ◽  
Toui Taniwaki ◽  
Kazuyoshi Miyagawa ◽  
...  
Keyword(s):  
Guide Vane ◽  
Internal Flow ◽  
Francis Turbine ◽  
Specific Speed

Transient characteristics of internal flow fields of mixed-flow pump with different tip clearances under stall condition

2020 ◽  
pp. 095765092096225
Author(s):  
Leilei Ji ◽  
Wei Li ◽  
Weidong Shi ◽  
Ramesh Agarwal
Keyword(s):  
Swirling Flow ◽  
Internal Flow ◽  
Flow Fields ◽  
Design Flow ◽  
Tip Clearance ◽  
Tip Leakage Flow ◽  
Mixed Flow ◽  
Transient Characteristics ◽  
Initial Starting ◽  
Flow Pump

This paper investigates the influence of different tip clearances on the transient characteristics of mixed-flow pump under stall condition. The instantaneous internal flow fields of mixed-flow pump with four tip clearances (0.2 mm, 0.5 mm, 0.8 mm and 1.1 mm) are explored by conducting unsteady time accurate simulations. Reynolds-averaged Navier-Stokes (RANS) equations are employed in the simulations and the results of computations are compared with experimental data. The results show that the pump head decreases by 22.1% and the pump efficiency drops by 13.9% at design flow condition when the impeller tip clearance increases from 0.2 mm to 1.1 mm. The swirling flow occurs in the inlet pipe of the mixed-flow pump with different tip clearances under stall condition, and the initial starting point of the swirling flow gets further away from the impeller inlet with increase in tip clearance because of increase in circumferential velocity and change in momentum of the tip leakage flow (TLF). The high turbulent eddy dissipation (TED) regions in the flow are attributed to the TLF, swirling flow, back flow and stall vortex, and their intensity are affected by the change in tip clearance. The oscillating trend of time domain distribution of TED enhances first and then decreases with increase in tip clearance and it exhibits a propagation feature under the effect of stall vortex, while most of the energy in the frequency domain remains concentrated in the low frequency part under stall condition.

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