CFD Wind Tunnel Tests of Centrifugal Stage Return Channel Vane Cascades

2015 ◽  
Author(s):  
Y. Galerkin ◽  
L. Marenina ◽  
K. Soldatova
Keyword(s):  
Incidence Angle ◽  
Flow Behavior ◽  
Radial Component ◽  
Loss Coefficient ◽  
Centrifugal Stage ◽  
Wide Range ◽  
Low Specific Speed ◽  
Specific Speed ◽  
Return Channel ◽  
Object Of Study

Stator part of a centrifugal compressor stage is a proper object of study by CFD calculations meaning better understanding of flow behavior, checking of field type design methods and possible improvements. Several stators with vane and vaneless diffusers for stages with different specific speed were designed by standard methodology and numerically analyzed. Results were verified. Calculation in a whole has demonstrated validity of existing recommendation. The specific velocity for stators is introduced which can be applied to match an impeller and a stator. Calculations demonstrated quick efficiency drop for stators with specific speed less than 0,215. Return channel vane cascades were studied in wide range of solidity with constant vane height and with constant radial component of velocity. Empirical formulae with non-dimensional circulation as an argument are proposed for loss coefficient, profile loss coefficient, optimal incidence angle and exit lag angle. Candidates of the low specific speed stator have demonstrated that an arbitrary channels’ wideness to diminish friction losses is not effective. Better flow organization is preferable. Modification of a crossover demonstrated positive results for high and low specific speed stators.

Rotating Cavitation in a Centrifugal Pump Impeller of Low Specific Speed

2002 ◽  
Vol 124 (2) ◽  
pp. 356-362 ◽  
Author(s):  
Jens Friedrichs ◽  
Gu¨nter Kosyna
Keyword(s):  
Centrifugal Pump ◽  
High Speed ◽  
Incidence Angle ◽  
Normal Operation ◽  
Pump Impeller ◽  
Wide Range ◽  
Low Specific Speed ◽  
Specific Speed ◽  
Cavity Closure ◽  
Operating Points

The paper describes an experimental investigation of two similar centrifugal pump impellers of low specific speed. Both impellers show rotating cavitation over a wide range of part load operating points. The occurrence of this phenomenon produces a characteristic shape of creeping head-drop compared to the more usual sudden head-drop at “normal” operation points. The onset of rotating cavitation can be assigned to a certain value of the parameter σ/2α meaning the cavity volume in relation to the incidence angle. Optical analysis by video and high-speed camera techniques illustrates the development of this instability mechanism which is mainly driven by an interaction of the cavity closure region and the following blade. Combining these observations and the results of a fourier-transformation the characteristic propagation frequencies of rotating cavitation can be presented for one impeller.

The Development of a Low Specific Speed Centrifugal Compressor Research Facility

2016 ◽  
Author(s):  
Jeanne Methel ◽  
William J. Gooding ◽  
John C. Fabian ◽  
Nicole L. Key ◽  
Mark Whitlock
Keyword(s):  
High Pressure ◽  
Centrifugal Compressor ◽  
Axial Compressor ◽  
Centrifugal Compressors ◽  
Centrifugal Stage ◽  
High Pressure Compressor ◽  
Low Specific Speed ◽  
Last Stage ◽  
Specific Speed ◽  
Consumption Goals

To achieve aggressive specific fuel consumption goals, aircraft engines are tending toward higher overall pressure ratios and higher bypass ratios for turbofans. As sizes decrease to meet these requirements, centrifugal compressors become a viable option as the last stage of the high pressure compressor. The last stages of an axial compressor in a small core engine face reduced efficiency due to the relatively large tip clearances with respect to blade height, and therefore, it may be more appropriate to finish the final compression stage with a low specific speed centrifugal compressor. A new facility, the Centrifugal STage for Aerodynamics Research (CSTAR) Facility, has been developed at Purdue University in cooperation with Rolls-Royce to gain further understanding of the complex aerodynamics found in such centrifugal compressors. The experimental data acquired in this facility will be utilized to develop and validate design tools for centrifugal compressors used in axial-centrifugal high-pressure compressors. The facility models the last (centrifugal) stage of an axial-centrifugal compressor and operates at engine-representative Mach numbers. In this paper, the facility is described in detail, and the baseline steady-state performance of the compressor is presented.

URBAN FACADE GEOMETRY ON OUTDOOR COMFORT CONDITIONS: A REVIEW

2020 ◽  
Vol 4 (1) ◽  
pp. 45
Author(s):  
Elahe Mirabi ◽  
Nasrollahi Nazanin
Keyword(s):  
Thermal Comfort ◽  
Urban Areas ◽  
Natural Ventilation ◽  
Flow Behavior ◽  
Air Flow ◽  
Urban Geometry ◽  
Wide Range ◽  
Low Energy Buildings ◽  
Outdoor Comfort ◽  
Solar Access

<p>Designing urban facades is considered as a major factor influencing issues<br />such as natural ventilation of buildings and urban areas, radiations in the<br />urban canyon for designing low-energy buildings, cooling demand for<br />buildings in urban area, and thermal comfort in urban streets. However, so<br />far, most studies on urban topics have been focused on flat facades<br />without details of urban layouts. Hence, the effect of urban facades with<br />details such as the balcony and corbelling on thermal comfort conditions<br />and air flow behavior are discussed in this literature review. <strong>Aim</strong>: This<br />study was carried out to investigate the effective factors of urban facades,<br />including the effects of building configuration, geometry and urban<br />canyon’s orientation. <strong>Methodology and Results</strong>: According to the results,<br />the air flow behavior is affected by a wide range of factors such as wind<br />conditions, urban geometry and wind direction. Urban façade geometry<br />can change outdoor air flow pattern, thermal comfort and solar access.<br /><strong>Conclusion, significance and impact study</strong>: In particular, the geometry of<br />the facade, such as indentation and protrusion, has a significant effect on<br />the air flow and thermal behavior in urban facades and can enhance<br />outdoor comfort conditions. Also, Alternation in façade geometry can<br />affect pedestrians' comfort and buildings energy demands.</p>

Theory and application of two-dimension viscous hydraulic design of the ultra-low specific-speed centrifugal pump

2019 ◽  
Vol 234 (1) ◽  
pp. 58-71 ◽  
Author(s):  
Cong Wang ◽  
Yongxue Zhang ◽  
Hucan Hou ◽  
Zhiyi Yuan
Keyword(s):  
Boundary Layer ◽  
Centrifugal Pump ◽  
Diagnostic Model ◽  
Two Dimension ◽  
Cavitation Performance ◽  
Hydraulic Design ◽  
Displacement Thickness ◽  
Low Specific Speed ◽  
Specific Speed ◽  
Low Efficiency

Low efficiency and bad cavitation performance restrict the development of the ultra-low specific-speed centrifugal pump (ULSSCP). In this research, combined turbulent boundary layer theory with two-dimension design and two-dimension viscous hydraulic design method has been proposed to redesign a ULSSCP. Through the solution of the displacement thickness in the boundary layer, a less curved blade profile with a larger outlet angle was obtained. Then the hydraulic and cavitation performance of the reference pump and the designed pump were numerically studied. The comparison of performance of the reference pump calculated by the numerical and experimental results revealed a better agreement. Research shows that the average hydraulic efficiency and head of the designed pump improve by 2.9% and 3.3%, respectively. Besides, the designed pump has a better cavitation performance. Finally, through the internal flow analysis with entropy production diagnostic model, a 24.8% drop in head loss occurred in the designed pump.

Optimal hydraulic design of an ultra-low specific speed centrifugal pump based on the local entropy production theory

2019 ◽  
Vol 233 (6) ◽  
pp. 715-726 ◽  
Author(s):  
Hucan Hou ◽  
Yongxue Zhang ◽  
Xin Zhou ◽  
Zhitao Zuo ◽  
Haisheng Chen
Keyword(s):  
Entropy Production ◽  
Centrifugal Pump ◽  
Orthogonal Design ◽  
High Energy ◽  
Geometrical Parameters ◽  
Production Theory ◽  
Local Entropy ◽  
Hydraulic Design ◽  
Low Specific Speed ◽  
Specific Speed

The ultra-low specific speed centrifugal pump has been widely applied in aerospace engineering, metallurgy, and other industrial fields. However, its hydraulic design lacks specialized theory and method. Moreover, the impeller and volute are designed separately without considering their coupling effect. Therefore, the optimal design is proposed in this study based on the local entropy production theory. Four geometrical parameters are selected to establish orthogonal design schemes including blade outlet setting angle, wrapping angle volute inlet width, and throat area. Subsequently, a 3D steady flow with Reynolds stress turbulent model and energy equation model is numerically conducted and the entropy production is calculated by a user-defined function code. The range analysis is made to identify the optimal scheme indicating that the combination of local entropy production and orthogonal design is feasible on pump optimization. The optimal pump is visibly improved with an increase of 1.08% in efficiency. Entropy production is decreased by 16.75% and 6.03% in impeller and volute, respectively. High energy loss areas are captured and explained in terms of helical vortex and wall friction, and the turbulent and wall entropy production are respectively reduced by 3.82% and 14.34% for the total pump.

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.

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