scholarly journals Investigations of drilled and multi-piped impellers cavitation performance

2019 ◽  
Vol 9 (1) ◽  
pp. 246-252
Author(s):  
Janusz Skrzypacz ◽  
Marcin Bieganowski
Keyword(s):  
High Efficiency ◽  
Static Pressure ◽  
Low Flow ◽  
Test Rig ◽  
Static Pressure Distribution ◽  
Cavitation Performance ◽  
Low Specific Speed ◽  
Cavitation Behavior ◽  
Nonstandard Approach ◽  
Industry Needs

AbstractThe industry needs the rotodynamic pumps operating with ultra-low specific speed and relatively low flow rate more often. Designing of such structures on acceptable efficiency level is extremely difficult and require nonstandard approach to design as for example: drilled impeller or patented by author multi-piped impeller. Such pump elements are very easy to manufacture and operate with relatively high efficiency, but cavitation behavior is unknown.This paper focuses on experimental research in order to determine the cavitation characteristics of the drilled impellers and multi-piped impellers. The test rig was presented. Impeller models were made by means of SLS Rapid Prototyping methods. Additionally, CFD calculations were presented in order to determine static pressure distribution in the inlet sections of the investigated impellers.

The Influence of the Regulator Diameter and Injection Nozzle Geometry on the Flow Structure in Pneumatic Dimensional Control Systems

1997 ◽  
Vol 119 (3) ◽  
pp. 609-615 ◽  
Author(s):  
C. Crnojevic ◽  
G. Roy ◽  
A. Bettahar ◽  
P. Florent
Keyword(s):  
Control Systems ◽  
Static Pressure ◽  
Separated Flow ◽  
Nozzle Geometry ◽  
Internal Diameter ◽  
Test Rig ◽  
Injection Nozzle ◽  
Static Pressure Distribution ◽  
Jet Nozzle ◽  
Experimental Findings

The present paper describes an experimental investigation of the various parameters affecting the operation of industrial pneumatic controllers based on the jet nozzle principle. A test rig was built to monitor supply pressure, air temperature, airflow characteristics, and the static pressure distribution over the flat plate on which the jet impinges. The results demonstrate the existence of a low pressure, separated flow zone, subject to fouling, which subsequently was eliminated by appropriate changes of the injection nozzle geometry. The previous experimental findings were also confirmed by numerical simulation of the flow. Experimental results also show that the internal diameter of the regulator, situated inside the measuring branch, has an important influence on the sensitivity of the apparatus, as well as influencing its range.

Effect of axial matching between inducer and centrifugal pump suction chamber on cavitation performance

2019 ◽  
Vol 234 (7) ◽  
pp. 947-956
Author(s):  
Xiaorui Cheng ◽  
Aimin Zhang
Keyword(s):  
Centrifugal Pump ◽  
Static Pressure ◽  
Three Dimensional ◽  
Axial Direction ◽  
Unit Weight ◽  
Axial Distance ◽  
Distribution Law ◽  
Pump Design ◽  
Static Pressure Distribution ◽  
Cavitation Performance

According to the design requirements of a booster centrifugal pump, the full three-dimensional numerical calculation of the model pump is carried out based on the RNG k-ɛ turbulence model and the Rayleigh–Plesset cavitation model to analyze the influence of the axial matching of the inducer and the suction chamber (i.e. the degree of the axial extension of the inducer into the suction chamber) on the cavitation performance of the centrifugal pump. Five sets of centrifugal pump design schemes were selected respectively with the ratio of the axial direction of the inducer into the suction chamber and the axial distance of the inducer hub were 0 (original scheme), 1.6%, 3.2%, 4.8%, and 6.4% to compare the distribution of axial static pressure of the inducer and the suction chamber, the variation of cavitation characteristics, head (energy of a fluid per unit weight obtained by working with a pump expressed in the form of height) and efficiency of the centrifugal pump, the distribution of bubbles in the inducer and the impeller, and the static pressure distribution law of the inducer in the runner. According to the results, what are illustrated are that the cavitation performance of the centrifugal pump can be improved by inserting the inducer into the suction chamber to a certain extent, and the cavitation performance is better with the increase of the axial indentation degree, but it tends to be stable after reaching a certain degree. At the same time, it was found that the vapor bubbles in the inducer and the impeller first appeared in the low pressure region at the inlet rim of the blade.

Loss Mechanisms in Shear-Force Pump With Multiple Corotating Disks

2014 ◽  
Vol 136 (8) ◽  
Author(s):  
Baotong Wang ◽  
Koji Okamoto ◽  
Kazuo Yamaguchi ◽  
Susumu Teramoto
Keyword(s):  
Numerical Simulation ◽  
Flow Field ◽  
Shear Force ◽  
High Efficiency ◽  
Internal Flow ◽  
Flow Coefficient ◽  
Low Flow ◽  
Test Rig ◽  
Pump System ◽  
Low Flow Coefficient

In a shear-force pump with multiple corotating disks, the pressure gain is obtained by utilizing the shear force produced on the surfaces of the rotating disks. Thus, it is expected to have advantages as a microfluid device compared to a conventional bladed compressor or pump, which suffers greatly from viscous loss. However, in previous studies, a shear-force pump could not achieve high efficiency in experiments, even though very good efficiencies were predicted in numerical and analytical studies on the flow field between corotating disks. Therefore, the objective of the present work was to investigate the internal flow dynamics and clarify the loss mechanisms in a complete shear-force pump device consisting of both rotor and stationary components. In order to achieve this goal, a numerical simulation using an independent rotor analysis was first performed on the internal flow field between two corotating disks to evaluate the isentropic efficiency and pressure coefficient that could be achieved. Then, an experimental test rig for a shear-force pump was designed and built, and an experiment was carried out to determine the performance of a complete pump device with the same corotating disk design as the independent rotor analysis. In addition, a numerical simulation was executed for the flow field of a pump system consisting of both rotor and stationary components based on the present test rig to investigate the flow field and loss factors of this device. The results of this independent rotor analysis showed that the corotating disks can achieve a fairly high efficiency at a low flow coefficient with a high dynamic pressure, and the flow direction is extremely close to the tangential direction at the disk outlet, which caused difficulties in the design of the diffuser and scroll. In the experimental test, the high total pressure loss in the parallel diffuser and scroll parts was observed. This was found to be the result of the significant friction loss caused by the long flow path due to strong recirculation in the diffuser and scroll volute, which was found in the simulation results for the internal flow in the whole pump system. In addition, a reverse flow appeared in the rotor part at a low flow coefficient, which significantly deteriorated the rotor performance. These conclusions provided some clues for improving the performance of a shear-force pump device in future work.

Suppression of Cavitation in a Francis Turbine Runner by Application of 3D Inverse Design Method

2002 ◽  
Author(s):  
Hidenobu Okamoto ◽  
Akira Goto
Keyword(s):  
High Efficiency ◽  
Static Pressure ◽  
Design Method ◽  
Three Dimensional ◽  
Inverse Design ◽  
Francis Turbine ◽  
Blade Loading ◽  
Static Pressure Distribution ◽  
Turbine Runner ◽  
Inverse Design Method

This paper describes a new design method of blade geometry for a Francis turbine runner by using a three-dimensional inverse design method and the Computational Fluid Dynamics (CFD) technique. The design objectives are the suppression of cavitation by reducing the area in which static pressure is lower than the vapor pressure while keeping the efficiency high. In the inverse design method, it is possible to optimize the static pressure distribution in the runner by controlling blade loading parameters and/or stacking condition, which is related to a blade lean angle, for the same design specification. A Francis turbine runner was re-designed by the inverse design method for different blade loading and stacking conditions, and the flow fields were evaluated by applying CFD. It was confirmed that the present design method is very practical and effective to control low pressure region and achieve high efficiency for Francis turbine runners.

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.

Experimental and Computational Analyses of Pressure Differentials in Flexible Ducts With Different Bent Angles

2007 ◽  
Author(s):  
Ray R. Taghavi ◽  
Wonjin Jin ◽  
Mario A. Medina
Keyword(s):  
Pressure Drop ◽  
Static Pressure ◽  
Complex Geometry ◽  
Analysis Data ◽  
Secondary Flows ◽  
Low Flow ◽  
Pressure Drops ◽  
Pressure Distributions ◽  
Geometrical Effects ◽  
Cfd Analyses

A set of experimental analyses was conducted to determine static pressure drops inside non-metallic flexible, spiral wire helix core ducts, with different bent angles. In addition, Computational Fluid Dynamics (CFD) solutions were performed and verified by comparing them to the experimental data. The CFD computations were carried out to produce more systematic pressure drop information through these complex-geometry ducts. The experimental setup was constructed according to ASHRAE Standard 120-1999. Five different bent angles (0, 30, 45, 60, and 90 degrees) were tested at relatively low flow rates (11 to 89 CFM). Also, two different bent radii and duct lengths were tested to study flexible duct geometrical effects on static pressure drops. FLUENT 6.2, using RANS based two equations - RNG k-ε model, was used for the CFD analyses. The experimental and CFD results showed that larger bent angles produced larger static pressure drops in the flexible ducts. CFD analysis data were found to be in relatively good agreement with the experimental results for all bent angle cases. However, the deviations became slightly larger at higher velocity regimes and at the longer test sections. Overall, static pressure drop for longer length cases were approximately 0.01in.H2O higher when compared to shorter cases because of the increase in resistance to the flow. Also, the CFD simulations captured more pronounced static pressure drops that were produced along the sharper turns. The stronger secondary flows, which resulted from higher and lower static pressure distributions in the outer and inner surfaces, respectively, contributed to these higher pressure drops.

Static pressure distribution in the free turbulent jet

1957 ◽  
Vol 3 (1) ◽  
pp. 1-16 ◽  
Author(s):  
David R. Miller ◽  
Edward W. Comings
Keyword(s):  
Static Pressure ◽  
Longitudinal Velocity ◽  
Fluid Motion ◽  
Mean Velocity ◽  
Free Jet ◽  
Static Pressure Distribution ◽  
Two Dimensional Flow ◽  
The Common ◽  
Jet Theory ◽  
Made In

Measurements of mean velocity, turbulent stress and static pressure were made in the mixing region of a jet of air issuing from a slot nozzle into still air. The velocity was low and the two-dimensional flow was effectively incompressible. The results are examined in terms of the unsimplified equations of fluid motion, and comparisons are drawn with the common assumptions and simplifications of free jet theory. Appreciable deviations from isobaric conditions exist and the deviations are closely related to the local turbulent stresses. Negative static pressures were encountered everywhere in the mixing field except in the potential wedge region immediately adjacent to the nozzle. Lateral profiles of mean longitudinal velocity conformed closely to an error curve at all stations further than 7 slot widths from the nozzle mouth. An asymptotic approach to complete self-preservation of the flow was observed.

Simulation on Linear-Motor-Driven Water Hydraulic Reciprocating Plunger Pump

2013 ◽  
Vol 842 ◽  
pp. 530-535 ◽  
Author(s):  
Zeng Meng Zhang ◽  
Yong Jun Gong ◽  
Jiao Yi Hou ◽  
Han Peng Wu
Keyword(s):  
Flow Rate ◽  
Deep Sea ◽  
High Efficiency ◽  
Control Method ◽  
Sea Water ◽  
Linear Motor ◽  
Low Flow ◽  
Flow Pulsation ◽  
Plunger Pump ◽  
Water Hydraulic

The water hydraulic reciprocating plunger pump driven by linear motor is suitable to deep sea application with high efficiency and variable control. Aiming to study the principle structure and working characteristics of the pump, two patterns of valve and piston distribution were designed. And the control method and the performance were analyzed by simulation based on the AMESim model. The results show that the pressure and flow pulsation of piston type pump are much smaller than the valve type, even though the piston type is large in scale and works at low flow rate. Compared with a valve distribution tri-linear-motor reciprocating plunger pump (VDTLMP), as the flow rate of the piston distribution double linear motor reciprocating plunger pump (PDDLMP) is decreased from 36.7 L/min to 21.2 L/min theoretically, the pressure pulsation amplitude is decreased from 46% to 2%, and the flow pulsation rate is also decreased from 0.266 to 0.007. These results contribute to the research on deep-sea water hydraulic power pack and direct drive pump with high efficiency and energy conservation.

Ingestion Into the Upstream Wheelspace of an Axial Turbine Stage

1994 ◽  
Vol 116 (2) ◽  
pp. 327-332 ◽  
Author(s):  
T. Green ◽  
A. B. Turner
Keyword(s):  
Pressure Distribution ◽  
Static Pressure ◽  
Three Dimensional ◽  
Computer Code ◽  
Rotor Blades ◽  
Rotor Speed ◽  
Turbine Stage ◽  
Flow Rates ◽  
Static Pressure Distribution ◽  
Axial Clearance

The upstream wheelspace of an axial air turbine stage complete with nozzle guide vanes (NGVs) and rotor blades (430 mm mean diameter) has been tested with the objective of examining the combined effect of NGVs and rotor blades on the level of mainstream ingestion for different seal flow rates. A simple axial clearance seal was used with the rotor spun up to 6650 rpm by drawing air through it from atmospheric pressure with a large centrifugal compressor. The effect of rotational speed was examined for several constant mainstream flow rates by controlling the rotor speed with an air brake. The circumferential variation in hub static pressure was measured at the trailing edge of the NGVs upstream of the seal gap and was found to affect ingestion significantly. The hub static pressure distribution on the rotor blade leading edges was rotor speed dependent and could not be measured in the experiments. The Denton three-dimensional C.F.D. computer code was used to predict the smoothed time-dependent pressure field for the rotor together with the pressure distribution downstream of the NGVs. The level and distribution of mainstream ingestion, and thus the seal effectiveness, was determined from nitrous oxide gas concentration measurements and related to static pressure measurements made throughout the wheelspace. With the axial clearance rim seal close to the rotor the presence of the blades had a complex effect. Rotor blades in connection with NGVs were found to reduce mainstream ingestion seal flow rates significantly, but a small level of ingestion existed even for very high levels of seal flow rate.

scholarly journals Performance Assessment of an Annular S-Shaped Duct

1995 ◽  
Author(s):  
D. W. Bailey ◽  
K. M. Britchford ◽  
J. F. Carrotte ◽  
S. J. Stevens
Keyword(s):  
Shear Stress ◽  
Static Pressure ◽  
Compressor Blade ◽  
Turbine Engines ◽  
Pressure Gradients ◽  
Gas Turbine Engines ◽  
Entry Length ◽  
Static Pressure Distribution ◽  
Flow Curvature ◽  
Inlet Conditions

An experimental investigation has been carried out to determine the aerodynamic performance of an annular S-shaped duct representative of that used to connect the compressor spools of aircraft gas turbine engines. For inlet conditions in which boundary layers are developed along an upstream entry length the static pressure, shear stress and velocity distributions are presented. The data shows that as a result of flow curvature significant streamwise pressure gradients exist within the duct, with this curvature also affecting the generation and suppression of turbulence. The stagnation pressure loss within the duct is also assessed and is consistent with the measured distributions of shear stress. More engine representative conditions are provided by locating a single stage compressor at inlet to the duct. Relative to the naturally developed inlet conditions the flow within the duct is less likely to separate, but mixing out of the compressor blade wakes increases the measured duct loss. With both types of inlet conditions the effect of a radial strut, such as that used for carrying loads and engine services, is also described both in terms of the static pressure distribution along the strut and its contribution to overall loss.

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