scholarly journals Multiobjective Optimization of Low-Specific-Speed Multistage Pumps by Using Matrix Analysis and CFD Method

2013 ◽  
Vol 2013 ◽  
pp. 1-10 ◽  
Author(s):  
Qiaorui Si ◽  
Shouqi Yuan ◽  
Jianping Yuan ◽  
Chuan Wang ◽  
Weigang Lu
Keyword(s):  
Multiobjective Optimization ◽  
Optimization Problems ◽  
Guide Vane ◽  
Matrix Analysis ◽  
Optimal Plan ◽  
Impeller Blade ◽  
Setting Angle ◽  
Shaft Power ◽  
Low Specific Speed ◽  
Specific Speed

The implementation of energy-saving and emission-reduction techniques has become a worldwide consensus. Thus, special attention should be provided to the field of pump optimization. With the objective of focusing on multiobjective optimization problems in low-specific-speed pumps, 10 parameters were carefully selected in this study for anL27(310) orthogonal experiment. The parameters include the outlet width of the impeller blade, blade number, and inlet setting angle of the guide vane. The numerical calculation appropriate for forecasting the performance of multistage pumps, such as the head, efficiency, and shaft power, was analyzed. Results were obtained after calculating the two-stage flow field of the pump through computational fluid dynamics (CFD) methods. A matrix method was proposed to optimize the results of the orthographic experiment. The optimal plan was selected according to the weight of each factor. Calculated results indicate that the inlet setting angle of the guide vane influences efficiency significantly and that the outlet angle of blades has an effect on the head and shaft power. A prototype was produced with the optimal plan for testing. The efficiency rating of the prototype reached 58.61%; maximum shaft power was within the design requirements, which verifies that the proposed method is feasible for pump optimization.

scholarly journals Automotive Research Compressor Experience

1989 ◽  
Author(s):  
R. C. Pampreen
Keyword(s):  
Gas Turbine ◽  
Centrifugal Compressor ◽  
Performance Characteristic ◽  
Lessons Learned ◽  
Impeller Blade ◽  
Blade Loading ◽  
Aerodynamic Loading ◽  
Development Experience ◽  
Low Specific Speed ◽  
Specific Speed

The design features and development experience of an advanced automotive gas turbine centrifugal compressor are presented. The compressor was designed with moderately low specific speed, high blade aerodynamic loading and design point on the choke characteristic. A cascade diffuser was used; a new design approach brought about an unusual performance characteristic. The influence of impeller blade loading on performance is presented. Lessons learned are summarized.

scholarly journals On the Rotor Stator Interaction Effects of Low Specific Speed Francis Turbines

2019 ◽  
Vol 2019 ◽  
pp. 1-11 ◽  
Author(s):  
Einar Agnalt ◽  
Igor Iliev ◽  
Bjørn W. Solemslie ◽  
Ole G. Dahlhaug
Keyword(s):  
Guide Vane ◽  
Pressure Fluctuations ◽  
Angular Position ◽  
Pressure Sensors ◽  
Pump Turbine ◽  
Blade Loading ◽  
Loading Case ◽  
Rotor Stator Interaction ◽  
Low Specific Speed ◽  
Specific Speed

The rotor stator interaction in a low specific speed Francis model turbine and a pump-turbine is analyzed utilizing pressure sensors in the vaneless space and in the guide vane cascade. The measurements are analyzed relative to the runner angular position by utilizing an absolute encoder mounted on the shaft end. From the literature, the pressure in the analyzed area is known to be a combination of two effects: the rotating runner pressure and the throttling of the guide vane channels. The measured pressure is fitted to a mathematical pressure model to separate the two effects for two different runners. One turbine with 15+15 splitter blades and full-length blades and one pump-turbine with six blades are investigated. The blade loading on the two runners is different, giving different input for the pressure model. The main findings show that the pressure fluctuations in the guide vane cascade are mainly controlled by throttling for the low blade loading case and the rotating runner pressure for the higher blade loading case.

Optimum Design and Experimental Study of a Very Low-Specific-Speed Centrifugal Blower Blade

2009 ◽  
Author(s):  
Xinwei Shu ◽  
Chuangang Gu ◽  
Tong Wang ◽  
Bo Yang
Keyword(s):  
High Pressures ◽  
Operating Cost ◽  
Experimental Studies ◽  
Approximate Model ◽  
Optimization Approach ◽  
Centrifugal Blower ◽  
Reference Case ◽  
Impeller Blade ◽  
Low Specific Speed ◽  
Specific Speed

Low-specific-speed centrifugal blowers are widely used in industries for compressing gases to high pressures at low flows. They have relatively low manufacturing and operating cost. However, their efficiency is fairly low as a result of relatively high leakage, disc friction and passage friction pressure loss. The purpose of this paper is to show how the performances can be improved by properly reshaping its blade profile using a developed multipoint optimization approach. The core of this approach is to build an approximate model mapping the correlation between certain blade shape parameters and corresponding aerodynamic performances. The approach is implemented by the combining a blade parameterization code, a three-dimensional viscous flow solver and several improved numerical optimization algorithms. A very low-specific speed industrial centrifugal blower with parallel hub and shroud has been selected as a reference case. The superior performances of the optimized impeller blade are demonstrated by comparing the performance improvement with that of the original blade. This is then confirmed by experimental studies.

Effects of Blade Wrap Angle Influencing a Pump as Turbine

2012 ◽  
Vol 134 (6) ◽  
Author(s):  
Sun-Sheng Yang ◽  
Fan-Yu Kong ◽  
Hao Chen ◽  
Xiang-Hui Su
Keyword(s):  
Theoretical Analysis ◽  
Pressure Head ◽  
Hydraulic Loss ◽  
Impeller Blade ◽  
Loss Distribution ◽  
Performance Change ◽  
Shaft Power ◽  
Wrap Angle ◽  
Specific Speed ◽  
Blade Wrap Angle

A pump is not ideally designed to operate as a turbine. To improve the efficiency of a pump as turbine (PAT), the redesign of the PAT, according to the flow of the turbine, is required. The blade wrap angle is one of the main geometric parameters in impeller design. Therefore, an investigation into the blade wrap angle to the PAT’s influence can be useful. In order to understand blade wrap angle to the influence of the PAT, this paper numerically investigated three different specific speeds of PATs with different blade wrap angles. The validity of numerical simulation was first confirmed through a comparison between numerical and experimental results. The performance change of the PATs with the blade wrap angle was acquired. A detailed hydraulic loss distribution and a theoretical analysis were performed to investigate the reasons for performance changes caused by the blade wrap angle. The results show that there is an optimal blade wrap angle for a PAT to achieve the highest efficiency and the optimal blade wrap angle decreases with an increasing specific speed. A performance analysis shows the PAT’s flow versus pressure head (Q-H) and flow versus generated shaft power (Q-P) curves are lowered with the decrease of the blade wrap angle. The hydraulic loss distribution and theoretical analysis illustrate that it is the decrease of hydraulic loss within the impeller, together with the decrease of the theoretical head, that results in the performance decrease. The decrease of hydraulic loss within the impeller is attributed to the shortened impeller blade passage and the reduced velocity gradient within the impeller flow channel. With the decrease of the blade wrap angle, the slip factor of the PAT’s impeller is decreased; therefore, its theoretical head is also decreased.

scholarly journals Numerical investigation on the effects of leakage flow from Guide vane-clearance gaps in low specific speed Francis turbines

2020 ◽  
Vol 1608 ◽  
pp. 012016
Author(s):  
Saroj Gautam ◽  
Ram Lama ◽  
Sailesh Chitrakar ◽  
Hari Prasad Neopane ◽  
Biraj Singh Thapa ◽  
...  
Keyword(s):  
Numerical Investigation ◽  
Guide Vane ◽  
Leakage Flow ◽  
Low Specific Speed ◽  
Specific Speed

Non-Overload Design of Low Specific Speed Submersible Pump

2010 ◽  
Author(s):  
Wei-dong Shi ◽  
Fei Long ◽  
Yue Li ◽  
Hong-fei Leng ◽  
Ping-ping Zou
Keyword(s):  
Pump Power ◽  
Geometrical Parameter ◽  
Input Power ◽  
Geometrical Parameters ◽  
Submersible Pump ◽  
Maximum Value ◽  
Shaft Power ◽  
Low Specific Speed ◽  
Specific Speed

Based on the design of low specific speed submersible pump, the influence of impeller geometrical parameter on shaft power of pump is analyzed in this paper. Under the condition of the maximum value of shaft power being no more than the input power of matching electromotor, the method of reducing the maximum value of pump power is researched further in order to reduce the power of the matching electromotor. Then the design correlation formula of the geometrical parameters of impeller is presented. The value of shaft power was predicted by the software FLUENT. The results show that the ratio of maximum power of pump to the power at designing condition is less than 1.2 when the correlation formula presented is used. The experimentation of prototype shows that the maximum value of shaft power of pump reduces greatly whilst every parameter meets the rated requirements. The results demonstrated the guiding role of the discriminated formula in practice, so the desired aim was achieved.

Investigation of the Flow Instabilities of a Low Specific Speed Pump-Turbine: Part 1 — Experimental and Numerical Analysis

2020 ◽  
Author(s):  
Sabri Deniz ◽  
Armando Del Rio ◽  
Martin von Burg ◽  
Manuel Tiefenthaler
Keyword(s):  
Experimental Data ◽  
Guide Vane ◽  
Turbulence Models ◽  
Operating Mode ◽  
Rotating Stall ◽  
Flow Instabilities ◽  
Pump Turbine ◽  
Flow Features ◽  
Low Specific Speed ◽  
Specific Speed

Abstract This is the first part of a two-part paper focusing on the flow instabilities of low-specific pump turbines. In this part, results of the CFD simulations and experiments of the research carried out on a low specific speed model pump-turbine at HSLU (Lucerne University of Applied Sciences) Switzerland are presented. The requirements of a stable and reliable pump-turbine operation under continuously expanding operating ranges, challenges the hydraulic design and requires new developments. Previous research at the HSLU [1] analyzed the instabilities of a medium specific speed (i.e. nq = 45) pump turbine. This paper presents the results of experimental (model pump-turbine at the test rig) and numerical (CFD) investigations of the pump-turbine instabilities of a low specific speed (nq = 25) pump-turbine in the turbine operating mode in the region of S-shaped characteristics (that is where the pump-turbine is synchronized and oscillations may occur during load rejection). The four-quadrant characteristics of a low specific speed model pump-turbine with two similar runners differentiating in the size (diameter) are measured. Testing of both runners with the same guide vane system provided information about the effects of the increased vaneless space (the distance between the guide vanes and runner) on the pump-turbine performance and stability both in turbine- and pump operating modes. A CFD methodology by using different numerical approaches and applying several turbulence models is developed in order to accurately predicting the characteristics of the reversible pump-turbines in the S-shaped region (speed no load conditions) as well as analyzing the flow features especially at off-design conditions. This CFD model is validated against the experimental data at 6° and 18° guide vane openings in turbine operating mode. With the measured data of the unsteady pressure measurements and detailed investigation of unstable ranges on the pump-turbine characteristics, flow instabilities in the low-specific speed model pump-turbine are analyzed. Relevant frequencies such as rotating stall, steady and unsteady vortex formations are determined. Based on the analysis of the experimental data and CFD results focusing especially on the flow features in the vaneless space and at the runner inlet, the onset and development of the flow instabilities are explored.

Investigation of Interaction Between Tip Leakage Flow Generated by Unshrouded Impeller and Diffuser Internal Flow

2018 ◽  
Author(s):  
Asuma Ichinose ◽  
Norio Kimura ◽  
Mamiko Yoshimura ◽  
Tomoyuki Hayashi ◽  
Kazuyoshi Miyagawa
Keyword(s):  
Pressure Distribution ◽  
Experimental Verification ◽  
Cfd Simulation ◽  
Internal Flow ◽  
Leakage Flow ◽  
Tip Leakage Flow ◽  
Impeller Blade ◽  
Tip Leakage ◽  
Low Specific Speed ◽  
Specific Speed

Rocket turbo pumps and industrial pumps such as water feed pumps are required to work under high pressure conditions, therefore low specific speed pumps are needed in spite of high rotational speed. In recent years, unshrouded impellers were used because of easy manufacturing and cost reduction. However, when low specific speed unshrouded impellers are used in such conditions, complex tip leakage flow occur and decrease impeller performance. In addition, splitter blades are often used, the internal flow becomes even more complicated. Therefore, such the internal flow of the unshrouded impeller must be clarified. In this research, we have studied such a centrifugal pump, and we have analyzed the internal flow using experiments and CFD (Computational Fluid Dynamics) simulations. The experimental verification was carried out by measuring the total pressure distribution on the outlet of the impeller and the diffuser. The unsteady static pressure distribution at the shroud side of the impeller was measured to confirm pump performance. We used two types of CFD simulation to evaluate the internal flow in detail. In the first CFD simulation, the unsteady internal flow of an impeller was evaluated by carrying out DES (Detached Eddy Simulation) with a periodic boundary condition that does not contain the diffuser. In the second CFD simulation, interaction between the impeller leakage flow and the diffuser internal flow was evaluated by DES with the whole impeller and diffuser. From the experimental verification and CFD simulation, it was confirmed that a large-scale vortex structure caused by the tip leakage flow and the secondary flow was observed in the impeller blade-to-blade. And the influence of the impeller leakage flow on the diffuser internal flow and the diffuser performance was evaluated. From the above studies, it was confirmed that the tip leakage flow has a large influence on the impeller internal flow and the diffuser performance.

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