Clocking effect in a centrifugal pump with a vaned diffuser

2020 ◽  
Vol 34 (26) ◽  
pp. 2050286
Author(s):  
Fen Lai ◽  
Xiangyuan Zhu ◽  
Yongqiang Duan ◽  
Guojun Li
Keyword(s):  
Centrifugal Pump ◽  
Flow Rate ◽  
Pressure Loss ◽  
Total Pressure ◽  
Radial Force ◽  
Design Flow ◽  
Total Pressure Loss ◽  
Inlet Section ◽  
Centrifugal Pumps ◽  
Installation Angle

The performance and service life of centrifugal pumps can be influenced by the clocking effect. In this study, 3D numerical calculations based on the k-omega shear stress transport model are conducted to investigate the clocking effect in a centrifugal pump. Time-averaged behavior and transient behavior are analyzed. Results show that the optimum diffuser installation angle in the centrifugal pump is [Formula: see text] due to the minimum total pressure loss and radial force acting on the impeller. Total pressure loss, particularly in the volute, is considerably influenced by the clocking effect. The difference in total pressure loss in the volute at different clocking positions is 2.75 m under the design flow rate. The large total pressure loss in the volute is primarily caused by the large total pressure gradient within the vicinity of the volute tongue. The radial force acting on the impeller is also considerably affected by the clocking effect. When the diffuser installation angle is [Formula: see text], flow rate fluctuations in the volute and impeller passage are minimal, and flow rate distribution in the diffuser passage is more uniform than those in other diffuser installation angles. Moreover, static pressure fluctuations in the impeller midsection and the diffuser inlet section are at the minimum value. These phenomena explain the minimum radial force acting on the impeller. The findings of this study can provide a useful reference for the design of centrifugal pumps.

scholarly journals Efficiency improvement and evaluation of a centrifugal pump with vaned diffuser

2019 ◽  
Vol 11 (3) ◽  
pp. 168781401982590 ◽  
Author(s):  
Kai Wang ◽  
Yu-cheng Jing ◽  
Xiang-hui He ◽  
Hou-lin Liu
Keyword(s):  
Centrifugal Pump ◽  
Axial Force ◽  
Flow Rate ◽  
Pressure Pulsation ◽  
Energy Performance ◽  
Radial Force ◽  
Design Flow ◽  
Vaned Diffuser ◽  
Original Scheme ◽  
Design Flow Rate

In order to enhance the efficiency of centrifugal pump, the structure of a centrifugal pump with vaned diffuser, whose specific speed is 190, was numerically improved by trimming back-blades of impeller and smoothing sharp corner in annular chamber. The energy performance, the internal flow field, the axial force, the radial force, and the pressure pulsation of the pump were analyzed. Results show that efficiency of the improving scheme 1 under the design flow rate is 77.47%, which can balance 69.82% of the axial force, while efficiency of the improving scheme 2 under the design flow rate is the maximum, which could still balance 62.74% of the axial force. The pressure pulsations of the improving scheme 2 at the typical monitoring points are less than that of the improving scheme 1 and the original scheme. The difference of the radial force peak between the improving scheme 1 and the improving scheme 2 is very small. The vector distributions of the radial force of the improving scheme 1 and the improving scheme 2 are more uniform than that of the original scheme. Considering the efficiency, pressure pulsation, and axial force, experiment measurements on the improving scheme 2 were carried out to verify the effectiveness of the improvement result. Results of energy performance experiment show that efficiency of the improving scheme 2 under the design flow rate is 76.48%, which is 5.26 percentage points higher than that of the original scheme.

Pressure Fluctuation of the Low Specific Speed Centrifugal Pump

2012 ◽  
Vol 152-154 ◽  
pp. 935-939 ◽  
Author(s):  
Qiang Fu ◽  
Shou Qi Yuan ◽  
Rong Sheng Zhu
Keyword(s):  
Centrifugal Pump ◽  
Flow Rate ◽  
Pressure Fluctuation ◽  
High Frequency ◽  
Pressure Fluctuations ◽  
Radial Force ◽  
Design Flow ◽  
Rate Condition ◽  
Low Specific Speed ◽  
Specific Speed

In order to study the rules of pressure fluctuation and the radial force under different positions in a centrifugal pump with low specific speed, and to find the relationship between each other, the three-dimensional ,unsteady Reynolds-averaged Navier-stokes equations with shear stress transport turbulent models were solved. The pressure fluctuation was obtained. The results showed that the pressure fluctuations were visible. The pressure fluctuations in the volute were relatively low at the design flow rate condition. The blade passing frequency dominates the pressure fluctuations, high frequency contents were found on the outlet of impeller but no high frequency information occured in casing. The radial force on the impeller was unsteady especially at the small flow rate.

scholarly journals Effects of impeller trim on performance of two-stage self-priming centrifugal pump

2017 ◽  
Vol 9 (2) ◽  
pp. 168781401769249 ◽  
Author(s):  
Kai Wang ◽  
Zixu Zhang ◽  
Linglin Jiang ◽  
Houlin Liu ◽  
Yu Li
Keyword(s):  
Centrifugal Pump ◽  
Flow Rate ◽  
Pressure Fluctuation ◽  
Guide Vane ◽  
Radial Force ◽  
Design Flow ◽  
Two Stage ◽  
Rate Condition ◽  
Application Range ◽  
Save Energy

In order to save energy by broadening its application range, the influence of impeller trim on the performance of a two-stage self-priming centrifugal pump was numerically studied. The hydraulic performance experiments and self-priming experiments were carried out. And the unsteady performance of pressure fluctuation and radial force in the pump was analyzed. The results show that with the increase in impeller trim quantity, the best efficiency point of the pump would move to the small flow rate condition. Under the design flow rate, when both the two stages of the impeller were trimmed by 6%, head of the pump was reduced by 13%, efficiency of the pump was as well decreased by 1.69 percentage points, and self-priming time was increased by 1.7%. Thus, impeller trim can be used to meet the operating requirements in the head range of 94–107 m. With the increase in impellers trim quantity, the pressure fluctuation in the positive channel of the radial guide vane and the volute was smaller, while the radial force on the wall of radial guide vane and volute was also smaller.

Optimal Design of the Volute for a Turbocharger Radial Flow Compressor

2014 ◽  
Author(s):  
Mohammad Mojaddam ◽  
Ali Hajilouy-Benisi ◽  
Mohammad Reza Movahhedy
Keyword(s):  
Pressure Loss ◽  
Total Pressure ◽  
Radial Flow ◽  
Pressure Ratio ◽  
Radial Force ◽  
Total Pressure Loss ◽  
Effective Parameters ◽  
Flow Rates ◽  
Design Point ◽  
Flow Compressor

In this research the design methods of radial flow compressor volutes are reviewed and the main criterions in volute primary designs are recognized and most effective ones are selected. The effective parameters i.e. spiral cross section area, circumferential area distribution, exit cone and tongue area of the compressor volute are parametrically studied to identifythe optimum values. A numerical model is prepared and verified through experimental data which are obtained from the designed turbocharger test rig. Different volutes are modeled and numerically evaluated using the same impeller and vane-less diffuser. For each model, the volute total pressure ratio, static pressure recovery and total pressure loss coefficients and the radial force on the impeller are calculated for different mass flow rates at design point and off-design conditions. The volute which shows better performanceand causes lower the net radial force on the impeller, at desiredmass flow rates is selected as an optimal one. The results show the volute design approach differences at the design point and off-design conditions. Improving the pressure ratio and reducing total pressure loss at design point, may result inthe worse conditions at off-design conditions as well as increasing radial force on the impeller.

Analysis of the Pressure Pulsation and Vibration in a Low-Specific-Speed Centrifugal Pump

2020 ◽  
Vol 143 (2) ◽  
Author(s):  
Baoling Cui ◽  
Yingbin Zhang ◽  
Yakun Huang
Keyword(s):  
Centrifugal Pump ◽  
Flow Rate ◽  
Vortex Core ◽  
Pressure Pulsation ◽  
Radial Force ◽  
Design Flow ◽  
Low Flow ◽  
Pressure Pulsations ◽  
Low Specific Speed ◽  
Specific Speed

Abstract Unsteady pressure pulsation and fluid force induced by flow instabilities in the centrifugal pump is an important cause of vibration, which is detrimental to the safe operation of the pump. In this study, we numerically investigated the pressure pulsation and radial force in a low-specific-speed centrifugal pump by using the detached-eddy simulation method. We also performed a vibration displacement experiment on the shaft of the centrifugal pump. The vortex identification method was introduced to clarify the internal correlation between unsteady flow structures with pressure pulsations. The results showed that the pressure pulsations at the impeller outlet were closely associated with the periodic vortex shedding from the blade pressure surface. The rotor–stator interaction between a relatively big trailing vortex core and volute tongue generated larger pressure pulsation and radial force in the pump at a low flow rate. Under a large flow rate, the trailing vortex core was easily broken and dispersed, and this resulted in smaller pressure pulsation and radial force compared with that at a low flow rate. Under the design flow rate, the pressure pulsation intensity and the radial force in the impeller were smaller than that under the off-design flow rate. Compared with the spectra between the radial force on the impeller and radial displacement on the shaft, they both presented higher amplitude at the shaft frequency. The vibration of the pump shaft was closely related to the radial force on the impeller.

Numerical and Experimental Investigation on the Radial Force Characteristic of a Large Double Suction Centrifugal Pump in a Real Pumping Station

2015 ◽  
Author(s):  
Zhifeng Yao ◽  
Fujun Wang ◽  
Zichao Zhang ◽  
Ruofu Xiao ◽  
Chenglian He
Keyword(s):  
Centrifugal Pump ◽  
Flow Rate ◽  
Radial Force ◽  
Operating Conditions ◽  
Design Flow ◽  
Force Characteristic ◽  
Flow Rates ◽  
Pump Operation ◽  
Pumping Station ◽  
Pump Shaft

The pump operation stability is one of the most important indicators for large discharge pumping stations. Impeller seal rings wear is a key problematic issue. A large double suction centrifugal pump in a real water supply pumping station is numerically and experimentally investigated, of which the seal rings are seriously wore on a fixed location. The pump shaft throws in two orthorhombic directions are measured at flow rates ranging from 0 to 110% of nominal flow rate, as well as the startup and shut down periods. And careful analysis of radial forces under various steady and unsteady conditions is carried out combining with the experimental results. The results show that the value of the shaft displacement obviously increases as the flow rate decreases, especially on the operating conditions with the flow rates below 87% of the design flow rate for the drive end side. The absolute value of the shaft displacement is 0.37mm, which is more than 3 times as large as that at nominal operating condition. There exit a lasting time of large shaft displacements during pump startup and shutdown periods, and the largest value of shaft displacement at the drive end side happens during the pump startup process, which can be increase to 0.95mm. There exists relative large radial force, and the direction of which is exactly the same with the pump shaft displacement at the flow rate from 0.73Qn to 0.32Qn, and also meet the wear locations of the impeller seal rings.

Flow Instability in Off Design Condition of Vaned and Vaneless Diffuser Centrifugal Pump

2015 ◽  
Author(s):  
Hideto Hiramatsu ◽  
Akiha Shibata ◽  
Shutaro Komaki ◽  
Kazuyoshi Miyagawa ◽  
Takeshi Sano
Keyword(s):  
Centrifugal Pump ◽  
Pressure Loss ◽  
Total Pressure ◽  
Internal Flow ◽  
Leading Edge ◽  
Propagation Speed ◽  
Rotating Stall ◽  
Total Pressure Loss ◽  
Speed Ratio ◽  
Vaneless Diffuser

In this study, the performance and the internal flow of one stage model centrifugal pump with both vaned and vaneless diffuser were investigated. To measure the internal flow of the diffuser and the impeller easily, air was used in this pump test. As a result of measuring pressure fluctuation, the rotating stall was observed in the vaned and vaneless diffuser. We clarified the generating mechanism and characteristics of the rotating stall in the diffuser and the difference between the unsteady flow fields in both diffusers. In case of the vaned diffuser, the number of rotating stall cells were 4 in the diffuser and the cell propagation speed ratio was about 5 percent of the impeller rotating speed. On the other hand, in case of the vaneless diffuser, the cell number was 2, and the propagation speed ratio was about 10 percent of that. These phenomena in both diffuser pumps were simulated by unsteady 2D and 3D CFD computations. By using these computations, the vortex at the trailing edge of the diffuser vanes blocked the flow and induced separate flow at the leading edge resulted in the rotating stall. This research indicated that these vortices induced the total pressure loss increasing. Also, the rotating stall was found not only in the diffuser but also in the impeller by the flow simulation of the vaneless diffuser. And it was confirmed that the vortices at the impeller trailing edge and leading edge in the stall cells cause the total pressure loss.

Effect of the honeycomb tip with injection on the aerodynamic performance in a 1.5-stage turbine

2020 ◽  
pp. 1-25
Author(s):  
Jianyang Yu ◽  
Yabo Wang ◽  
YanPing Song ◽  
Fu Chen
Keyword(s):  
Mass Flow Rate ◽  
Mass Flow ◽  
Flow Rate ◽  
Pressure Loss ◽  
Total Pressure ◽  
Total Pressure Loss ◽  
Navier Stokes ◽  
Total Efficiency ◽  
Cavity Depth ◽  
Tip Leakage

Abstract Three kinds of rotor tip configurations have been investigated numerically in the LISA 1.5-stage turbine, including the flat tip, the honeycomb tip and the honeycomb tip with injection. The effect of the cavity depth and the injection mass flow rate on the turbine performance is studied in detail, evaluated by the isentropic total-to-total efficiency and the tip leakage mass flow rate. The Reynolds-averaged Navier-Stokes (RANS) method and the k-ω turbulence model are adopted in all the present computations. The numerical results show that the first stage efficiency is increased by up to 0.66% and the tip leakage mass flow rate is reduced by about 1.87% of the main flow. The pressure field and the flow feature inside the gap are explored. The flow structures and the total pressure loss contours in the rotor passage are presented. Finally, the total pressure loss is newly defined by considering the injection effect. It is indicated that the injection mass flow rate should be carefully determined for excellent overall performance.

Effect of the Double-Slot Injection on the Leakage Flow Control in a Honeycomb-Tip Turbine Cascade

2019 ◽  
Author(s):  
Yabo Wang ◽  
Yanping Song ◽  
Jianyang Yu ◽  
Fu Chen
Keyword(s):  
Flow Control ◽  
Mass Flow Rate ◽  
Mass Flow ◽  
Flow Rate ◽  
Pressure Loss ◽  
Total Pressure ◽  
Total Pressure Loss ◽  
Leakage Flow ◽  
Turbine Cascade ◽  
Tip Leakage

Abstract The effect of five arrangements of the double-slot injections on the leakage flow control is studied in a honeycomb-tip turbine cascade numerically. The honeycomb tip is covered with 67 intact honeycomb cavities, since the uneven tip is wearable and the cavity vortex could realize the aerodynamic sealing for the leakage flow. Then in the present study, a pair of injection slots is arranged blow each cavity, aiming to enhance the leakage flow suppression by modifying the cavity vortex. According to the orientation of the two slots, five designs of the double-slot injections are proposed. In detail, the two slots are opposite to each other or keep tangential to the original cavity vortex roughly. The three dimensional calculations were completed by using Reynolds-averaged Navier-Stokes (RANS) method and the k-ω turbulence model in the commercial software ANSYS CFX. The estimation of these tip designs is mainly according to the tip leakage mass flow rate and the total pressure loss. Firstly, the injection structures induced by the slots can be divided into X- and T-types inside the cavity. The results show that the T-type structure is more effective in reducing the tip leakage mass flow rate, with the maximum reduction up to 48.2%. Then the effect on the flow field inside the gap and the secondary flow in the upper passage is analyzed. Compared with the flat tip, the span-wise position of the tip leakage vortex core drops within the cascade and the range of the affected loss region expands. At the cascade exit, the tip leakage vortex moves toward the passage vortex near the casing, while the latter’s core rises. The position changes of the secondary vortices eventually determine the total pressure loss contour downstream the cascade. Finally, the injection total pressure and the upper casing motion are investigated. Interestingly, the injection intensity (mass flow rate) increases with the injection total pressure but this value decreases as the casing speed increases. The tip leakage mass flow rate decreases linearly as increasing the injection total pressure or the casing speed. Yet the averaged total pressure loss downstream the cascade increases with the injection total pressure but appears a nonlinear distribution against the casing speed.

Experimental Measurements of Pressure Losses in the Inter-Turbine Duct of a Gas Turbine

2015 ◽  
Vol 789-790 ◽  
pp. 540-548 ◽  
Author(s):  
Cleopatra Florentina Cuciumita ◽  
Daniel Olaru ◽  
Valeriu Vilag ◽  
Ionut Porumbel ◽  
Sergiy Riznyk ◽  
...  
Keyword(s):  
Gas Turbine ◽  
Mass Flow Rate ◽  
Flow Rate ◽  
Rotational Speed ◽  
Pressure Loss ◽  
Total Pressure ◽  
Operating Regime ◽  
Total Pressure Loss ◽  
Experimental Measurements ◽  
Pressure Losses

The paper presents the total pressure experimental measurements carried out at the Romanian Research and Development Institute for Gas Turbines COMOTI in order to determine the total pressure losses in the Inter - Turbine Duct of a two spools gas turbine, as a function of the gas turbine operating regime (mass flow rate) and rotational speed. The Inter - Turbine Duct experimental assembly has been designed, manufactured and tested at COMOTI. The total pressures were measured as a function of the pre-swirling angle, which simulates the influence of the high pressure turbine rotational speed located upstream of the Inter turbine duct in the real gas turbine, as well as for three operational regimes, without the pre-swirlers modules. The results indicate that the total pressure loss along the Inter - Turbine Duct is of maximum 0.9 %. The lowest overall total pressure loss occurs at 0o pre-swirling angle, around 0.8%, while along the ITD struts, the lowest pressure loss is obtained for a 15o pre-swirling, below 0.1%. The influence of the operating regime on the total pressure loss was found to be linearly, the pressure loss increasing with the reduced mass flow rate, between 1% and 1.9% overall, and between about 0.1% and 0.4 % along the struts.

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