Optimization of a Centrifugal Impeller on Blade Thickness Distribution to Reduce Hydro-Induced Vibration

2019 ◽  
Vol 142 (2) ◽  
Author(s):  
Bo Qian ◽  
Peng Wu ◽  
Bin Huang ◽  
Kai Zhang ◽  
Shiyang Li ◽  
...  
Keyword(s):  
Secondary Flow ◽  
Thickness Distribution ◽  
Suction Side ◽  
Centrifugal Impeller ◽  
Impeller Blade ◽  
Vibration Data ◽  
Streamwise Location ◽  
Blade Thickness ◽  
Computational Fluid Dynamics Cfd ◽  
Vibration Performance

Abstract The vibration performance of centrifugal impellers is important for pumps and hydraulic excitation is a key source of vibration. The complex internal secondary flow in the centrifugal impeller brings degradation on vibration performances. An attempt of optimization by controlling the thickness distribution of centrifugal impeller blade is given to repress the internal secondary flow and alleviating vibration. The usual method of modifying an impeller on vibration performance is applying splitter blades. In this study, an ordinarily designed impeller is improved by the optimization attempt and the optimized impeller (OPT) is compared with the prototype impeller (PRT) with traditional splitter blades. The vibration performances of the impellers, the PRT, the ordinary impeller (ODN), and the OPT, are investigated numerically and experimentally. Meanwhile, further study on the influence of the thickness distribution optimization on vibration is conducted. There is a relative velocity gradient from suction side (SS) to pressure side (PS) in impeller ODN, causing nonuniformity of energy distribution. By means of thickness distribution optimization, the impeller blade angle on the PS and SS along the blade-aligned streamwise location is, respectively, modified and therefore the flow field can be reordered. The energy transfer in impeller is also redistributed after the modification of blade thickness distribution. What is more, experimental research upon impeller PRT and impeller OPT is also complemented to support the computational fluid dynamics (CFD) results. The experimental results show that the hydraulic performance of the impellers basically agree with the CFD results and the vibration data also proves a better vibration performance of the OPT.

Optimization and Investigation on the Impact of Centrifugal Impeller Blade Thickness Distribution on Hydro-Induced Vibration

2018 ◽  
Author(s):  
B. Qian ◽  
D. Z. Wu
Keyword(s):  
Secondary Flow ◽  
Thickness Distribution ◽  
Suction Side ◽  
Centrifugal Impeller ◽  
Impeller Blade ◽  
Streamwise Location ◽  
Unbalanced Rotor ◽  
Blade Thickness ◽  
Vibration Performance ◽  
The Impact

The vibration performance of centrifugal impellers is of great importance for pumps in some application areas such as automobiles and ships. Apart from mechanical excitations for instance, unbalanced rotor and misalignment, attentions should be concentrated on the hydraulic excitations. The complex internal secondary flow in the centrifugal impeller brings degradation on both hydraulic and vibration performances. On the purpose of repressing the internal secondary flow and alleviating vibration, an attempt of optimization by controlling the thickness distribution of centrifugal impeller blade is given. The vibration performances of the impellers are investigated numerically and experimentally. Meanwhile, further study on the mechanism of the influence of the thickness distribution optimization on vibration is conducted. There is a relative velocity gradient from suction side (SS) to pressure side (PS) due to the Coriolis force, which causes non-uniformity of energy distribution. By means of thickness distribution optimization, the impeller blade angle on the PS and SS along the blade-aligned (BA) streamwise location is respectively modified and therefore the flow field can be improved.

Investigation of the Wake Effect From the Centrifugal Splitter Impeller Blade to the Vaned Diffuser

2012 ◽  
Author(s):  
Xuechen Li ◽  
Guang Xi ◽  
Jiang Hua ◽  
Wuqi Gong
Keyword(s):  
Flow Characteristics ◽  
Suction Side ◽  
Wake Flow ◽  
Centrifugal Impeller ◽  
Wake Effect ◽  
Impeller Blade ◽  
Vaned Diffuser ◽  
Side Pressure ◽  
Unsteady Wake ◽  
Impeller Outlet

In this paper, the unsteady wake effect from an unshrouded centrifugal impeller with splitter blades was numerically and experimentally investigated. The numerical simulated detail flow characteristics of two stations, respectively placed at the impeller outlet and the diffuser inlet, were compared with the measured data. The “jet-wake” flow pattern was observed at the exit of the impeller. And the investigation showed that the wake effect of the splitter was weaker that of the main blade. But both the main blade and the splitter blade wake could affect the diffuser performance at a range of whole-chord length and they provoked the pressure side profile pressure fluctuating intensely from 10% chord to 50% chord, while the suction side pressure varying rapidly at the range from 60% chord to 80% chord.

NUMERICAL INVESTIGATIONS OF A CENTRIFUGAL BLOOD PUMP

2004 ◽  
Vol 04 (03) ◽  
pp. 237-255 ◽  
Author(s):  
W. K. CHAN ◽  
Y. W. WONG ◽  
Y. DING
Keyword(s):  
Leading Edge ◽  
Suction Side ◽  
Small Region ◽  
Inverse Design ◽  
Blood Pump ◽  
Impeller Blade ◽  
Centrifugal Blood Pump ◽  
Computational Fluid Dynamics Cfd ◽  
Inlet Angle ◽  
Side Flow

This paper presents computational fluid dynamics (CFD) studies of a centrifugal blood pump. 3-D models of five different blade geometries are investigated numerically using CFX-TASCflow. The impellers were designed using an inverse design technique where the swirl distributions were prescribed. The results showed the flow in the impeller passages is highly dependent on the impeller blade profiles. The flow in the radial blade impeller is unsatisfactory as flow separates at the leading edge of the suction side. Flow is confined mainly to the pressure side. Design 2, with an inlet angle of 6.7° and outlet angle of 30°, offers the greatest potential as only a small region of flow reversal is detected. Further optimization is necessary to completely eliminate regions of flow reversals. The highest scalar shear stress in both designs is 240 Pa and 120 Pa respectively. In addition, this paper demonstrates that the use of inverse design can help the designer to better design and analyze the flow field in centrifugal blood pumps.

scholarly journals Inverse Design of Turbomachinery Blading for Arbitrary Blade Thickness in Three-Dimensional Transonic Flow

1997 ◽  
Author(s):  
Y. L. Yang
Keyword(s):  
Thickness Distribution ◽  
Three Dimensional ◽  
Suction Side ◽  
Entropy Change ◽  
Inverse Design ◽  
Pressure Side ◽  
Vortex Sheets ◽  
Blade Thickness ◽  
Blade Row ◽  
The Mean

A three-dimensional inverse design of turbomachinery blading for arbitrary blade thickness was obtained by using two periodic bound vortex sheets representing the pressure side and suction side of a blade row. The mean swirl distribution and blade tangential thickness distribution are specified in the present inverse design method. The prescribed mean swirl distribution is split into two fractions to form the strength of two bound vortex sheets. However, the designed results are uniquely determined by the specification of the mean swirl distribution and blade tangential thickness distribution, while splitting the mean swirl distribution into any two fractions for two bound vortex sheets is irrelevant. The resulting velocity field is composed of three parts: the first is sawtooth integrated from two bound vortex sheets; the second is axisymmetrical to provide an irrotational flow outside the two bound vortex sheets; and the last is potential to ensure mass conservation. The blade shape is determined from either the pressure side or suction side boundary condition, without a difference. Numerical results of a subsonic stator blade row designed by the present inverse design have been compared with three-dimensional Euler solutions and show a good agreement. For transonic calculation, a special form of retarding density was implemented to avoid transformation of the coordinate. However, due to the nonisentropic and rotational nature of shock wave, the present inverse solution does not give a correct answer after shocks. Coupling the entropy change and generation of vorticity after shocks with the present analytical formulation is recommended in the future work.

scholarly journals Secondary Flow Mixing Losses in a Centrifugal Impeller

1982 ◽  
Author(s):  
M. W. Johnson ◽  
J. Moore
Keyword(s):  
Boundary Layer ◽  
Secondary Flow ◽  
Suction Side ◽  
Boundary Layer Separation ◽  
Centrifugal Impeller ◽  
Cross Sectional ◽  
Flow Measurements ◽  
Layer Separation ◽  
Flow Mixing ◽  
Rotating Impeller

Detailed flow measurements made in a 1-m dia shrouded centrifugal impeller running at 500 rpm are presented. All 3 mutually perpendicular components of relative velocity and rotary stagnation pressures were measured on 5 cross-sectional planes between the inlet and the outlet, using probes which were traversed within the rotating impeller passage. The reduced static pressures were also calculated from these flow measurements. The measurements were made for an impeller flow rate corresponding to approximately zero incidence at the blade leading edges. Shroud boundary layer separation and secondary flow were observed to lead to the formation of a wake in the suction-side/shroud corner region. It is concluded that the turbulent mixing associated with the shroud boundary layer separation and the strength of the secondary flow strongly influence the size and location of the wake respectively.

Secondary Flow Mixing Losses in a Centrifugal Impeller

1983 ◽  
Vol 105 (1) ◽  
pp. 24-32 ◽  
Author(s):  
M. W. Johnson ◽  
J. Moore
Keyword(s):  
Boundary Layer ◽  
Secondary Flow ◽  
Suction Side ◽  
Boundary Layer Separation ◽  
Centrifugal Impeller ◽  
Cross Sectional ◽  
Flow Measurements ◽  
Layer Separation ◽  
Flow Mixing ◽  
Rotating Impeller

Detailed flow measurements made in a 1-m dia shrouded centrifugal impeller running at 500 rpm are presented. All three mutually perpendicular components of relative velocity and rotary stagnation pressures were measured on five cross-sectional planes between the inlet and the outlet, using probes which were traversed within the rotating impeller passage. The reduced static pressures were also calculated from these flow measurements. The measurements were made for an impeller flow rate corresponding to approximately zero incidence at the blade leading edges. Shroud boundary layer separation and secondary flow were observed to lead to the formation of a wake in the suction-side/shroud corner region. It is concluded that the turbulent mixing associated with the shroud boundary layer separation and the strength of the secondary flow strongly influence the size and location of the wake, respectively.

A Study on the Effects of Blade Thickness on the Performance of Low Specific Speed Centrifugal Pump

2014 ◽  
Vol 1070-1072 ◽  
pp. 1957-1962 ◽  
Author(s):  
Yong Xin Jin ◽  
Wen Wu Song ◽  
Fu Jie
Keyword(s):  
Centrifugal Pump ◽  
Three Dimensional ◽  
Leaf Thickness ◽  
Centrifugal Impeller ◽  
Flow Area ◽  
Impeller Blade ◽  
Performance Effect ◽  
Blade Thickness ◽  
Low Specific Speed ◽  
Specific Speed

The effects of blade thickness on impeller performance is seldom considered when design the low specific speed centrifugal pump and only considered crowding coefficient when use the speed coefficient method calculate the head of the impeller was designed. It was didn't consider the fundamental relationship how leaf thickness and low specific speed centrifugal impeller performance effect each other. The three-dimensional of flow area would have large influence if the leaf thickness changes . Here the best true thickness of the low specific speed centrifugal impeller blade was obtained though study how the thickness of blade influence on the performance of low specific speed centrifugal pump.

Unsteady Flow Phenomena in Rotating Centrifugal Impeller Passages

1970 ◽  
Vol 92 (1) ◽  
pp. 65-71 ◽  
Author(s):  
E. Lennemann ◽  
J. H. G. Howard
Keyword(s):  
Unsteady Flow ◽  
Secondary Flow ◽  
Centrifugal Impeller ◽  
Bubble Flow ◽  
Hydrogen Bubble ◽  
Visualization Technique ◽  
Rotating Systems ◽  
Flow Phenomena ◽  
Relative Flow ◽  
Zero Flow

The phenomena of unsteady relative flow observed in a centrifugal impeller passage running at part capacity and zero flow are discussed. The mechanisms of passage stall for a shrouded and unshrouded impeller are investigated and a qualitative correlation is developed for the influence of secondary flow and inducer flow on the passage stall. The hydrogen bubble flow visualization technique is extended to higher velocities and rotating systems and provides the method for obtaining the experimental results.

Effect of Wake Passing on Unsteady Aerodynamic Performance in a Turbine Stage

2006 ◽  
Author(s):  
K. Yamada ◽  
K. Funazaki ◽  
K. Hiroma ◽  
M. Tsutsumi ◽  
Y. Hirano ◽  
...  
Keyword(s):  
Secondary Flow ◽  
Three Dimensional ◽  
Suction Side ◽  
Turbine Stage ◽  
Three Dimensional Flow ◽  
Unsteady Aerodynamic ◽  
Unsteady Effect ◽  
Unsteady Rans ◽  
Wake Passing ◽  
Stage Efficiency

In the present work, unsteady RANS simulations were performed to clarify several interesting features of the unsteady three-dimensional flow field in a turbine stage. The unsteady effect was investigated for two cases of axial spacing between stator and rotor, i.e. large and small axial spacing. Simulation results showed that the stator wake was convected from pressure side to suction side in the rotor. As a result, another secondary flow, which counter-rotated against the passage vortices, was periodically generated by the stator wake passing through the rotor passage. It was found that turbine stage efficiency with the small axial spacing was higher than that with the large axial spacing. This was because the stator wake in the small axial spacing case entered the rotor before mixing and induced the stronger counter-rotating vortices to suppress the passage vortices more effectively, while the wake in the large axial spacing case eventually promoted the growth of the secondary flow near the hub due to the migration of the wake towards the hub.

scholarly journals Aerothermal Investigations of Mixing Flow Phenomena in Case of Radially Inclined Ejection Holes at the Leading Edge

1999 ◽  
Author(s):  
Dieter E. Bohn ◽  
Karsten A. Kusterer
Keyword(s):  
Flow Field ◽  
Secondary Flow ◽  
Gas Turbines ◽  
Leading Edge ◽  
Suction Side ◽  
Pressure Side ◽  
Blade Surface ◽  
Cooling Fluid ◽  
Flow Phenomena ◽  
Vortex Systems

A leading edge cooling configuration is investigated numerically by application of a 3-D conjugate fluid flow and heat transfer solver, CHT-Flow. The code has been developed at the Institute of Steam and Gas Turbines, Aachen University of Technology. It works on the basis of an implicit finite volume method combined with a multi-block technique. The cooling configuration is an axial turbine blade cascade with leading edge ejection through two rows of cooling holes. The rows are located in the vicinity of the stagnation line, one row is on the suction side, the other row is on the pressure side. The cooling holes have a radial ejection angle of 45°. This configuration has been investigated experimentally by other authors and the results have been documented as a test case for numerical calculations of ejection flow phenomena. The numerical domain includes the internal cooling fluid supply, the radially inclined holes and the complete external flow field of the turbine vane in a high resolution grid. Periodic boundary conditions have been used in the radial direction. Thus, end wall effects have been excluded. The numerical investigations focus on the aerothermal mixing process in the cooling jets and the impact on the temperature distribution on the blade surface. The radial ejection angles lead to a fully three dimensional and asymmetric jet flow field. Within a secondary flow analysis it can be shown that complex vortex systems are formed in the ejection holes and in the cooling fluid jets. The secondary flow fields include asymmetric kidney vortex systems with one dominating vortex on the back side of the jets. The numerical and experimental data show a good agreement concerning the vortex development. The phenomena on the suction side and the pressure side are principally the same. It can be found that the jets are barely touching the blade surface as the dominating vortex transports hot gas under the jets. Thus, the cooling efficiency is reduced.

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