Influence of non-uniform inflow on unsteady internal flow characteristics of waterjet pump

2021 ◽  
Author(s):  
Chao Liu ◽  
Hongxun Chen ◽  
Zheng Ma
Keyword(s):  
High Speed ◽  
Pressure Pulsation ◽  
Guide Vane ◽  
Flow Characteristics ◽  
Internal Flow ◽  
Energy Performance ◽  
Hydrodynamic Characteristics ◽  
Area Formula ◽  
Low Speed ◽  
Waterjet Pump

Waterjet propulsion has many advantages when operating at high-speed conditions. As a special way of navigation, it is mostly used in high-speed ships and shallow draft ships. In this paper, a mixed-flow waterjet pump was taken as the research object. For the two cases of non-uniform inflow and uniform inflow, a modified RANS/LES method was adopted for unsteady calculation of the whole channel, aiming at investigating the influence mechanism of the non-uniform inflow on the energy performance and pressure pulsation characteristics of the waterjet pump. The hydrodynamic characteristics of the waterjet pump were comprehensively analyzed such as head, efficiency, axial-force, internal flow and pressure pulsation. It is found that the non-uniform inflow will reduce the external characteristics of the waterjet pump and lead to the huge fluctuation of energy performance with time. Low-speed swirls occur locally in the intake duct for non-uniform inflow, in which condition the vorticity is much higher than that for uniform inflow. In terms of the low-speed area, [Formula: see text] and [Formula: see text], the values under non-uniform inflow condition are generally larger than those under uniform flow condition when in the impeller and guide vane zone. The dominant frequencies of pressure pulsation are, respectively, [Formula: see text], 7[Formula: see text] and 4[Formula: see text] in the intake duct, impeller and diffuser, which are almost consitent for the two cases. However, the frequency features are more diverse, and the amplitudes corresponding to the same frequencies are more intense for non-uniform inflow.

scholarly journals Analysis of Internal Flow Characteristics of a Startup Pump Turbine at the Lowest Head under No-Load Conditions

2021 ◽  
Vol 9 (12) ◽  
pp. 1360
Author(s):  
Wei Wang ◽  
Xi Wang ◽  
Zhengwei Wang ◽  
Mabing Ni ◽  
Chunan Yang
Keyword(s):  
High Speed ◽  
Pressure Pulsation ◽  
Working Condition ◽  
Guide Vane ◽  
Flow Characteristics ◽  
Internal Flow ◽  
Operating Conditions ◽  
Small Range ◽  
Pressure Balance ◽  
Pump Turbine

The instability of the no-load working condition of the pump turbine directly affects the grid connection of the unit, and will cause vibration and damage to the components of the unit in severe cases. In this paper, a three-dimensional full flow numerical model including the runner gap and the pressure-balance pipe was established. The method SST k-ω model was used to predict the internal flow characteristics of the pump turbine. The pressure pulsation of the runner under different operating conditions during the no-load process was compared. Because the rotation speed, flow rate, and guide vane opening of the unit change in a small range during the no-load process, the pressure pulsation characteristics of the runner are basically the same. Therefore, a working condition was selected to analyze the transient characteristics of the flow field, and it was found that there was a high-speed ring in the vaneless zone, and a stable channel vortex was generated in the runner flow passage. Analyzing the axial water thrust of each part of the runner, it was found that the axial water thrust of the runner gap was much larger than the axial water thrust of the runner blades, and it changed with time periodically. It was affected by rotor stator interaction. The main frequency was expressed as a multiple of the number of guide vanes, that is, vanes passing frequency, 22fn. During the entire no-load process, the axial water thrust of the runner changed slowly with time and fluctuated slightly.

scholarly journals Dynamic simulation of inner flow in a photovoltaic pump based on Simulink and CFD

2021 ◽  
Author(s):  
Xianfang Wu ◽  
Heyu Ye ◽  
Minggao Tan ◽  
Houlin Liu
Keyword(s):  
Solar Radiation ◽  
Pressure Pulsation ◽  
Transient Flow ◽  
Guide Vane ◽  
Flow Characteristics ◽  
Internal Flow ◽  
Maximum Error ◽  
Pump System ◽  
Impeller Outlet ◽  
Pump Flow Rate

Abstract To study the internal flow characteristics of the photovoltaic pump under the transient change of the solar radiation, the simulation algorithm of the photovoltaic pump system was established by MATLAB/Simulink and CFD for the first time and the results were validated by the test. Firstly, the change rule of pump flow rate and rotation speed under transient solar radiation was obtained by Simulink. Then the results of the change rule were transformed into the boundary condition of CFD by CEL function and the transient flow field in the photovoltaic pump was obtained. The internal flow characteristics and pressure pulsation in the pump were analyzed when the solar radiation increases or decreases transiently. The results demonstrate that the numerical calculation can provide accurate prediction for the characteristics of internal flow in the pump. The numerical results are closed to experimental results, the minimum error of pressure is 0.93% and the maximum error is 1.78%. When the solar radiation increases transiently, the low pressure area at the impeller inlet gets larger obviously and the jet-wake at the impeller outlet becomes more obvious. The pressure pulsation in impeller gradually increases and becomes stable after 0.6 s. The pressure from the impeller outlet to guide vane outlet is stable at 123 kPa. When the solar radiation decreases transiently, the pressure in the impeller takes 1.6 s to be stable. Larger pressure pulsation occurs from the impeller outlet to the guide vane inlet and the maximum differential pressure is 10 kPa. Compared with the transient increase of solar radiation, the pressure in the impeller takes more 0.2 s to stabilize when the solar radiation transient decreases. Meanwhile, the results in this paper can provide references for other transient characteristics research.

scholarly journals Numerical and Experimental Investigation of External Characteristics and Pressure Fluctuation of a Submersible Tubular Pumping System

Processes ◽  
2019 ◽  
Vol 7 (12) ◽  
pp. 949 ◽  
Author(s):  
Yan Jin ◽  
Xiaoke He ◽  
Ye Zhang ◽  
Shanshan Zhou ◽  
Hongcheng Chen ◽  
...  
Keyword(s):  
Numerical Simulation ◽  
Pressure Fluctuation ◽  
High Efficiency ◽  
Pressure Pulsation ◽  
Guide Vane ◽  
Measurement Data ◽  
Flow Characteristics ◽  
Measuring Point ◽  
Pumping System ◽  
Impeller Outlet

This paper presents an investigation of external flow characteristics and pressure fluctuation of a submersible tubular pumping system by using a combination of numerical simulation and experimental methods. The steady numerical simulation is used to predicted the hydraulic performance of the pumping system, and the unsteady calculation is adopted to simulate the pressure fluctuation in different components of a submersible tubular pumping system. A test bench for a model test and pressure pulsation measurement is built to validate the numerical simulation. The results show that the performance curves of the calculation and experiment are in agreement with each other, especially in the high efficiency area, and the deviation is minor under small discharge and large discharge conditions. The pressure pulsation distributions of different flow components, such as the impeller outlet, middle of the guide vane, and guide vane outlet and bulb unit, are basically the same as the measurement data. For the monitoring points on the impeller and the wall of the guide vane especially, the main frequency and its amplitude matching degree are higher, while the pressure pulsation values on the wall of the bulb unit are quite different. The blade passing frequency and its multiples are important parameters for analysis of pressure pulsation; the strongest pressure fluctuation intensity appears in the impeller outlet, which is mainly caused by the rotor–stator interaction. The farther the measuring point from the impeller, the less the pressure pulsation is affected by the blade frequency. The frequency amplitudes decrease from the impeller exit to the bulb unit.

A Study on Improvement of Aerodynamic Performance for 100HP Axial Fan Blade and Guide Vane Using Response Surface Method

2019 ◽  
Author(s):  
Young-Seok Choi ◽  
Yong-In Kim ◽  
Sung Kim ◽  
Seul-Gi Lee ◽  
Hyeon-Mo Yang ◽  
...  
Keyword(s):  
Objective Function ◽  
Response Surface ◽  
Response Surface Method ◽  
Guide Vane ◽  
Three Dimensional ◽  
Flow Characteristics ◽  
Internal Flow ◽  
Aerodynamic Performance ◽  
Axial Fan ◽  
Surface Method

Abstract This paper describes the numerical optimization of an axial fan focused on the blade and guide vane (GV). For numerical analysis, three-dimensional (3D) steady-state Reynolds-averaged Navier-Stokes (RANS) equations with the shear stress transport (SST) turbulence model are discretized by the finite volume method (FVM). The objective function is enhancement of aerodynamic performance with specified total pressure. To select the design variables which have main effect to the objective function, 2k factorial design is employed as a method for design of experiment (DOE). In addition, response surface method (RSM) based on the central composite design applied to carry out the single-objective optimization. Effects on the components such as bell mouth and hub cap are considered with previous analysis. The internal flow characteristics between base and optimized model are analyzed and discussed.

scholarly journals A Comparative Study on Centrifugal Pump Designs and Two-Phase Flow Characteristic under Inlet Gas Entrainment Conditions

Energies ◽  
2019 ◽  
Vol 13 (1) ◽  
pp. 65 ◽  
Author(s):  
Qiaorui Si ◽  
Gérard Bois ◽  
Minquan Liao ◽  
Haoyang Zhang ◽  
Qianglei Cui ◽  
...  
Keyword(s):  
Pressure Pulsation ◽  
Two Phase Flow ◽  
Three Dimensional ◽  
Flow Characteristics ◽  
Internal Flow ◽  
Phase Flow ◽  
Water Mixture ◽  
Centrifugal Pumps ◽  
Two Phase ◽  
Void Fractions

Capability for handling entrained gas is an important design consideration for centrifugal pumps used in petroleum, chemistry, nuclear applications. An experimental evaluation on their two phase performance is presented for two centrifugal pumps working under air-water mixture fluid conditions. The geometries of the two pumps are designed for the same flow rate and shut off head coefficient with the same impeller rotational speed. Overal pump performance and unsteady pressure pulsation information are obtained at different rotational speeds combined with various inlet air void fractions (α0) up to pump stop condition. As seen from the test results, pump 2 is able to deliver up to 10% two-phase mixtures before pump shut-off, whereas pump 1 is limited to 8%. In order to understand the physics of this flow phenomenon, a full three-dimensional unsteady Reynolds Average Navier-Stokes (3D-URANS) calculation using the Euler–Euler inhomogeneous method are carried out to study the two phase flow characteristics of the model pump after corresponding experimental verification. The internal flow characteristics inside the impeller and volute are physically described using the obtained air distribution, velocity streamline, vortex pattern and pressure pulsation results under different flow rates and inlet void fractions. Pump performances would deteriorate during pumping two-phase mixture fluid compared with single flow conditions due to the phase separating effect. Some physical explanation about performance improvements on handing maximum acceptable inlet two phase void fractions capability of centrifugal pumps are given.

scholarly journals Internal flow characteristics in scaled pressure-swirl atomizer

2018 ◽  
Vol 180 ◽  
pp. 02059 ◽  
Author(s):  
Milan Malý ◽  
Marcel Sapík ◽  
Jan Jedelský ◽  
Lada Janáčková ◽  
Miroslav Jícha ◽  
...  
Keyword(s):  
High Speed ◽  
Laser Doppler Anemometry ◽  
Flow Characteristics ◽  
Internal Flow ◽  
Liquid Sheet ◽  
Wide Range ◽  
Swirl Atomizer ◽  
Pressure Swirl ◽  
Pressure Swirl Atomizer ◽  
Working Liquid

Pressure-swirl atomizers are used in a wide range of industrial applications, e.g.: combustion, cooling, painting, food processing etc. Their spray characteristics are closely linked to the internal flow which predetermines the parameters of the liquid sheet formed at the discharge orifice. To achieve a better understanding of the spray formation process, the internal flow was characterised using Laser Doppler Anemometry (LDA) and high-speed imaging in a transparent model made of cast PMMA (Poly(methyl methacrylate)). The design of the transparent atomizer was derived from a pressure-swirl atomizer as used in a small gas turbine. Due to the small dimensions, it was manufactured in a scale of 10:1. It has modular concept and consists of three parts which were ground, polished and bolted together. The original kerosene-type jet A-1 fuel had to be replaced due to the necessity of a refractive index match. The new working liquid should also be colourless, non-aggressive to the PMMA and have the appropriate viscosity to achieve the same Reynolds number as in the original atomizer. Several liquids were chosen and tested to satisfy these requirements. P-Cymene was chosen as the suitable working liquid. The internal flow characteristics were consequently examined by LDA and high-speed camera using p-Cymene and Kerosene-type jet A-1 in comparative manner.

Influence of blade leaning on hydraulic excitation and structural response of a reversible pump turbine

2021 ◽  
pp. 095765092110349
Author(s):  
Jinhui Ouyang ◽  
Yongyao Luo ◽  
Ran Tao
Keyword(s):  
High Efficiency ◽  
Pressure Pulsation ◽  
Guide Vane ◽  
Equivalent Stress ◽  
Structural Response ◽  
Internal Flow ◽  
Pressure Side ◽  
Pump Mode ◽  
Runner Design ◽  
Turbine Mode

Blade leaning is commonly seen in the runner design of reversible pump turbines which operate under varying conditions. However, there is no certain law in determine the leaning mode and level. Considering performance, hydraulic excitation and structural response, five runners with strong rotational (RL+), rotational (RL), strong counter-rotational (CL+), counter-rotational (CL) and without (NL) blade leaning are compared under high-efficiency condition in pump mode and turbine mode. The head, efficiency, internal flow pressure pulsation and runner stress are comparatively studied. Among the five runners, CL+ runner is found has the highest efficiency as pump when RL+ runner has the highest efficiency as turbine. Pressure pulsation results show that the rotor-stator interaction region is the strongest pulsation source especially for runner and blade frequencies. In pump mode, pressure pulsation intensity decreases when blade leaning mode gradually changes from rotational to counter-rotational. In turbine mode, the NL runner has the strongest pressure pulsation intensity in runner and guide vane. Both rotational and counter-rotational leaning will reduce pressure pulsation. Velocity contours indicate that blade leaning will affect the velocity uniformity especially along rotational direction and cause stronger or weaker local hydraulic excitation. Under hydraulic excitation, RL+ runner suffers the highest equivalent stress as pump while CL runner suffers the highest equivalent stress as turbine. From rotational to counter-rotational blade leaning, the maximum stress moves on the crown from low pressure side to high pressure side. Considering hydraulic excitation and structural response, the strong counter-rotational leaning blade is found better in reversible runner design.

scholarly journals Investigation on the Transient Characteristics of Self-Priming Pumps with Different Hub Radii

Machines ◽  
2021 ◽  
Vol 9 (12) ◽  
pp. 311
Author(s):  
Hao Chang ◽  
Shiming Hong ◽  
Chuan Wang ◽  
Guangjie Peng ◽  
Fengyi Fan ◽  
...  
Keyword(s):  
Pressure Pulsation ◽  
Flow Characteristics ◽  
Internal Flow ◽  
Radial Force ◽  
Force Distribution ◽  
Surface Load ◽  
Blade Surface ◽  
Load Pressure ◽  
Transient Characteristics ◽  
Power Capability

Self-priming pumps, important fluid equipment, are widely used in the disaster relief and emergency fields. Meanwhile, the impeller is the only rotational unit of the self-priming pump, which plays an essential part in the power capability of the pump. In this paper, impellers with different hub radii are proposed; by comparing the internal flow characteristics, blade surface load, pressure pulsation characteristics, and radial force distribution of each scheme, the relationship between transient characteristics and hub radius is obtained. The results present that the impeller with a large hub radius can not only weaken the pressure pulsation, blade surface load, and radial force distribution, but also improve the ability of the blade to work on the internal flow field. Finally, the relevant hydraulic experiment is conducted, with the difference between the experiment and calculation below 3%, which ensures the accuracy of the calculation results.

Experimental and Numerical Researches in a Four-Stage Low Speed Research Compressor Facility

2020 ◽  
Author(s):  
Mingmin Zhu ◽  
Xiaoqing Qiang ◽  
Zhenzhou Ju ◽  
Yuchen Ma ◽  
Jinfang Teng
Keyword(s):  
Guide Vane ◽  
Axial Compressor ◽  
Internal Flow ◽  
Flow Fields ◽  
Inlet Guide Vane ◽  
External Diameter ◽  
Low Speed ◽  
Single Passage ◽  
Overall Performance ◽  
Inlet Conditions

Abstract The flow fields in rear stages of multi-stage axial compressor is difficult to measure in detail owing to the limited height and space. Thus, low speed research compressor (LSRC) facilities which are modelled from rear stages have been widely used to explore the internal flow fields and improve compressor design. A newly-designed vertical LSRC facility is established and put into used in Shanghai Jiao Tong University. The construction and design features of this LSRC facility are introduced in this paper. A cantilevered stage has been tested in this test rig. Compressor performance, inter-stage parameters distributions and contours are measured at design point and near stall point. Steady single passage simulations for four-stage compressor are carried out to validate numerical methods and further interpret the internal flow fields in test stages. This vertical LSRC facility consists of inlet guide vane (IGV) and four repeated stages with an external diameter of 1.5 meter and a rotating speed of 900 RPM. The third stage is the mainly tested one, while the first and second stages provide the inlet conditions and the fourth stage provides the outlet conditions. Complete measuring methods and systems are established for this newly-built LRSC facility. The measurements of overall performance and inter-stage flow fields are carried out for test stage with cantilevered stator rows. The simulation for four-stage compressor are also performed for cantilevered configuration. The results of steady single-passage simulation have a similar trend with experimental ones, in terms of overall performance and parameters distributions.

New Centrifugal Pump in Very Low Specific Speed Range

2011 ◽  
Author(s):  
Shusaku Kagawa ◽  
Junichi Kurokawa
Keyword(s):  
Centrifugal Pump ◽  
High Speed ◽  
Cfd Simulation ◽  
Flow Characteristics ◽  
Internal Flow ◽  
Rotating Disk ◽  
Capacity Curve ◽  
Speed Range ◽  
Low Specific Speed ◽  
Specific Speed

In the range of very low specific speed, such as ns < 80 [min.−1, m3/min., m], or Ns < 533 [min.−1, USGPM, ft.], stable head-capacity curve is one of the most important issues. The head-capacity curve of a conventional closed impeller tends to be unstable with a positive slope characteristic in such a very low ns range. To solve this problem, a new type of centrifugal pump “J-groove pump” is proposed and tested in this study. The J-groove pump is composed of a rotating disk mounted with many shallow radial grooves and a circular casing. The experimental results reveal that the proposed J-groove pump is quite effective in the very low specific speed range. The pump head is about 1.2 times higher than that of a conventional centrifugal pump and the head-capacity curve is almost stable, though the efficiency becomes a little lower because of a large friction power of the stationary wall. The cavitation performance is also measured and is shown to be almost same as that of a conventional centrifugal pump. This pump is applicable to high speed pump, as it has no small clearance, high strength due to simple impeller configuration, and easy to assemble. In order to determine the internal flow characteristics of the J-groove pump, CFD simulation is carried out. It is revealed that the high head of the J-groove pump is caused by a strong vortex flow existing in both clearances near the impeller tip over the whole flow range.

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