Experimental Investigation of the Complete Characteristics of Rotodynamic Pumps

2009 ◽  
Author(s):  
Erkan Ayder ◽  
Ayhan N. Ilikan ◽  
Mete S¸en ◽  
Cahit O¨zgu¨r ◽  
Levent Kavurmacıog˘lu ◽  
...  
Keyword(s):  
Measurement Techniques ◽  
Pipeline System ◽  
Mixed Flow ◽  
Pump Design ◽  
Pump Failure ◽  
Undesirable Event ◽  
Measuring Devices ◽  
Essential Parameter ◽  
Specific Speed ◽  
Unsteady Conditions

Pump failure in a pipeline system can occur for several reasons and this undesirable event causes waterhammer phenomenon. While designing a pipeline system, minimum and maximum pressures caused by waterhammer and the variation of the pressure along the pipeline with respect to time must be determined. In order to calculate the time variation of the pressure, complete characteristics of a pump is used as one of the boundary conditions. In these unsteady conditions, the pump may turn in normal or reverse directions which define eight different working zones called pump, turbine, brake and booster. Specific speed is an essential parameter which affects characteristics of pumps. In the literature, for many years there have been only three complete pump characteristics obtained with the assistance of 1960’s measuring devices and techniques. Each one of those corresponds to pumps having centrifugal (nsq = 35), mixed flow (nsq = 147) or axial impeller (nsq = 261). Recently additional complete pump characteristics that belong to 14 different specific speeds have been published in the literature. By considering improvements in pump design during half a century and innovations in measurement techniques, the present study is performed to repeat experiments of complete characteristics of different specific speeds existing in the literature, and to obtain complete pump characteristics for different specific speeds. The complete characteristics of seven pumps with specific speeds of nsq = 20 – 23 – 33 – 55 – 105 – 209 and 261 are obtained experimentally. The results show that the complete characteristics of a pump is not only function of specific speed but also function of pump design. The number of the complete pump characteristics available in the literature is increased in this study. The obtained results revealed that, unlike the existing approach in the literature, the complete characteristics of pump that is used in the pipeline, must be used in the calculation of waterhammer pressures in the design of pipelines.

Experimental and Numerical Investigation of a Counter-Rotating Mixed-Flow Single Stage Pump

2015 ◽  
Author(s):  
Stefano Tosin ◽  
Jens Friedrichs ◽  
Andreas Dreiss
Keyword(s):  
Characteristic Curve ◽  
Speed Ratio ◽  
Centrifugal Pumps ◽  
Mixed Flow ◽  
Pump Design ◽  
Machine Performance ◽  
Novel Approach ◽  
Specific Speed ◽  
Definition Of ◽  
New Generation

A prototype of a new generation of centrifugal pumps has been developed, with aim to improve typical weaknesses like narrow operable range due to slip and incidence losses in off-design conditions. The peculiarity of this pump is the absence of any stator blade, which has been substituted with a counter-rotating radial impeller. According to an exhaustive literature survey, the usage of a mixed flow impeller as a front rotor, followed by a radial-flow impeller seems to be a novel approach in pump design. The combination of a high specific speed impeller with a low specific speed rotating diffuser produces a flexible adaptability against aforementioned limits. Keep on adding energy to the fluid instead of just diffusing the flow, permits to reach a downsized hydraulics and an increased entire machine power density. The characteristic of such a pump needs to be analyzed as 3D-surface, both speeds are actually independent and for a fixed discharge the head rise and efficiency become surfaces. A new definition of optimized characteristic curve, with variable speed ratio, could be identified based on those performance maps. A special test rig has been built to measure the machine performance, distinguishing the mechanical losses of both shafts separately with no-load measurements. The sensitivity of the system on speed ratio variation has been explored. The experiments show the presence of different best speed ratios which maximize alternately the head or the efficiency. Additionally, the results confirm the possibility to expand the working range acting on the rotational speeds. Head rise and efficiency curves with varying speed ratio, as functions of the flow rate are finally shown using several diagrams, highlighting the advantages of this new design.

Numerical and Experimental Study of Inner Flow and Hydraulic Performance of the Mixed-Flow Pump With Low Specific Speed

2018 ◽  
Author(s):  
Jianping Yuan ◽  
Meng Fan ◽  
Yanjun Li ◽  
Yanxia Fu ◽  
Rong Lu
Keyword(s):  
Rapid Development ◽  
Internal Flow ◽  
Fluctuation Analysis ◽  
Market Demand ◽  
Mixed Flow ◽  
Pump Design ◽  
Flow Rates ◽  
Low Specific Speed ◽  
Specific Speed ◽  
Flow Pump

Mixed flow pumps are very suitable for market demand with the rapid development of urbanization, especially for low specific speed mixed flow pumps which has been widely used in various fields [1–3]. In this study, the calculations of the incompressible 3D internal flow of the mixed-flow pump with low specific speed was carried out by using CFD technique based on the N-S equation coupled with the standard k-ε turbulence model at different flow rates. The hydraulic performances of the mixed-flow pump as well as the inner flow were analyzed in comparison with the corresponding experimental data. Meanwhile, the static pressure and relative velocity distribution on blades were studied at low, design as well as large flow rates, respectively. Finally, it can obtain that the predicted pump performance curves based on numerical simulation have a good agreement with the experimental results, which verify the numerical method applied in this work accurate in a certain extent. Furthermore, the results also provide some references to hydraulic forces and pressure fluctuation analysis and the performance improvement for the mixed-flow pump design.

Experimental Investigation of a Counter-Rotating Mixed-Flow Single Stage Pump Under Cavitation Conditions

2015 ◽  
Author(s):  
Stefano Tosin ◽  
Jens Friedrichs ◽  
Andreas Dreiss ◽  
Bruno Schiavello ◽  
Kariem Elebiary
Keyword(s):  
Pressure Coefficient ◽  
Speed Ratio ◽  
Manufacturing Cost ◽  
Variable Speed ◽  
Centrifugal Pumps ◽  
Mixed Flow ◽  
Pump Design ◽  
Cavitation Inception ◽  
Radial Pump ◽  
Specific Speed

The increase in power per unit volume in modern pumps has been driven by manufacturing cost reduction. The first prototype of a new generation of centrifugal pumps has been experimentally and numerically investigated. It presents a particular and novel design characterized by the absence of any stator blade, which has been substituted with a counter-rotating radial impeller. According to an exhaustive literature survey, the usage of a mixed-flow impeller as a front rotor, followed by a radial-flow impeller seems to be a novel approach in pump design. The combination of a high specific speed impeller with a low specific speed counter-rotating diffuser produces flexible adaptability against varying working conditions. It also gives a rise to an increase of pressure coefficient values beyond limits of similar volute envelope. Applying the counter-rotating design principle to a radial pump increases power density, however cavitation-related issues remains a limiting factor. Counter-rotating design also features an additional degree of freedom to the system due to the independency of motor speeds of one another. This aspect improved cavitation inception characteristics especially at overload capacities. Moreover, such an arrangement required building a special test rig in order to accommodate for the double motor configuration. In this study, the NPSH3% -curve and the NPSHic cavitation inception characteristics have been measured. The system dependency on speed ratio variation has been also investigated along with the influence of the speed ration on the cavitation. Results of the cavitation inception visualizations were obtained using an endoscope at front rotor in order to analyze the behaviour of the pump under cavitation conditions. Test results showed two distinct speed ratios where maximum head and best cavitiaiton behavior were achieved. Additionally, results also confirmed that the cavitaion-free range can be optimized by using different speed ratios. A head drop-efficiency curve with variable speed ratios, which have been progressively adjusted for several flow capacities, is developed. This curve highlights the advantage of this new design compared to a conventional pump particularly under off-design conditions. It is clearly evident that delaying head deterioration, due to low inlet available suction energy, is solely attributed to the variable speed ratio of the runners.

Automated Anthropometric Measuring Devices for Use in Mass-Screening

2000 ◽  
Vol 44 (38) ◽  
pp. 719-722
Author(s):  
William F. Moroney
Keyword(s):  
Mass Screening ◽  
State Of The Art ◽  
Measurement Techniques ◽  
The State ◽  
Anthropometric Measurement ◽  
Review Of The Literature ◽  
Measuring Devices ◽  
Measurement Devices ◽  
Electro Magnetic

The purpose of this paper is to describe the state of the art in anthropometric measuring devices used for mass screening. In addition, technologies which could be used for automated mass screening are identified and described. A review of the literature identified only two operational anthropometric measurement devices currently used for mass screening. A variety of potentially applicable measurement techniques including acoustic, light, electro-magnetic, potentiometric/electro-optical (including digitizing arms) technologies were identified and described. Data describing the capabilities and limitations of these systems are also provided.

Study on Electromagnetic Vibration Pump

2013 ◽  
Vol 774-776 ◽  
pp. 312-315
Author(s):  
Zhan Xiong Lu
Keyword(s):  
Research Field ◽  
Pump Design ◽  
Positive Displacement ◽  
Low Viscosity ◽  
Electromagnetic Vibration ◽  
Displacement Pump ◽  
Small Flow ◽  
Working Principle ◽  
Low Specific Speed ◽  
Specific Speed

Electromagnetic vibration pump is one type of first proposed new household positive displacement pump.It is mainly used to transport water and other low viscosity liquid. It has many advantages including small flow, high head, simple structure,good self-priming performance. Electromagnetic driving method was combined with displacement pump in vibration pump for the first time. Its specific speed can reach below 10,and this is a breakthrough in super-low specific speed pump design. The working principle of electromagnetic vibration pump and its performance were studied in the paper. each of these problems is further discussed and explained in order to point out the research field for the development of electromagnetic vibration pump later.

A comparative study of the performance of the mixed flow and radial flow variable geometry turbines for an automotive turbocharger

2018 ◽  
Vol 233 (8) ◽  
pp. 2696-2712 ◽  
Author(s):  
K Ramesh ◽  
BVSSS Prasad ◽  
K Sridhara
Keyword(s):  
Mass Flow ◽  
Flow Parameter ◽  
Radial Flow ◽  
Velocity Ratio ◽  
Variable Geometry ◽  
Flow Variable ◽  
Mixed Flow ◽  
Turbine Efficiency ◽  
Variable Geometry Turbine ◽  
Specific Speed

A new design of a mixed flow variable geometry turbine is developed for the turbocharger used in diesel engines having the cylinder capacity from 1.0 to 1.5 L. An equivalent size radial flow variable geometry turbine is considered as the reference for the purpose of bench-marking. For both the radial and mixed flow turbines, turbocharger components are manufactured and a test rig is developed with them to carry out performance analysis. Steady-state turbine experiments are conducted with various openings of the nozzle vanes, turbine speeds, and expansion ratios. Typical performance parameters like turbine mass flow parameter, combined turbine efficiency, velocity ratio, and specific speed are compared for both mixed flow variable geometry turbine and radial flow variable geometry turbine. The typical value of combined turbine efficiency (defined as the product of isentropic efficiency and the mechanical efficiency) of the mixed flow variable geometry turbine is found to be about 25% higher than the radial flow variable geometry turbine at the same mass flow parameter of 1425 kg/s √K/bar m2 at an expansion ratio of 1.5. The velocity ratios at which the maximum combined turbine efficiency occurs are 0.78 and 0.825 for the mixed flow variable geometry turbine and radial flow variable geometry turbine, respectively. The values of turbine specific speed for the mixed flow variable geometry turbine and radial flow variable geometry turbine respectively are 0.88 and 0.73.

Performance of a Mixed Flow Pump with Varying Tip Clearance: Part 2

1996 ◽  
Vol 210 (4) ◽  
pp. 319-327 ◽  
Author(s):  
S Soundranayagam ◽  
T K Saha
Keyword(s):  
Close Agreement ◽  
Tip Clearance ◽  
Pump Efficiency ◽  
Centrifugal Pumps ◽  
Mixed Flow ◽  
Loss Distribution ◽  
Specific Speed ◽  
Flow Pump ◽  
Relative Flow

Measurements in a mixed flow pump of non-dimensional specific speed k = 1.89 [ NS = 100 r/min (metric)] are analysed to give loss distribution and local hydraulic efficiencies at different flowrates and values of tip clearance. Fairly close agreement is obtained between the relative flow angles leaving the blading as predicted by simple deviation and slip models and derived from the measurements. The head developed is broken up into two parts: that contributed by Coriolis action and that associated with blade circulation. It is suggested that lift coefficients based on blade circulation are of limited value in selecting blade profiles. The variation of pump efficiency with tip clearance is greater than that reported for centrifugal pumps.

Unsteady Flow at the Outlet of the High Specific Speed Centrifugal Compressor Impeller

1984 ◽  
Author(s):  
Fumikata Kano ◽  
Takafumi Shirakami
Keyword(s):  
Unsteady Flow ◽  
Centrifugal Compressor ◽  
Coal Gasification ◽  
Three Dimensional ◽  
Axial Direction ◽  
Navier Stokes ◽  
Meridional Plane ◽  
Mixed Flow ◽  
Navier Stokes Equation ◽  
Specific Speed

The unsteady flow at the outlet of the high specific speed mixed flow Impeller was studied. The specific speed is 500 (m3/min)1/2 · rpm · m−3/4. The flow is strongly influenced by the impeller blading. The other hand, the flow influences the performance of the stationary vanes downstream of the impeller. The flow path at the outlet of the mixed flow impeller is inclined to the axial direction and is curved in the meridional plane. The study was carried out to develop the 30 MW centrifugal compressor. This compressor is used in the field of the coal gasification, the geothermal power generation, etc. The distributions of flow velocity, pressure and temperature of three dimensional flow were measured using a high sensitive pressure transducer and a total temperature probe. The flow was surveyed across the entire passage at about ten axial locations including endwall boundary layer. A theoretical analysis was also carried out using the linearized Navier-Stokes equation.

Case Study of Multi-Stage Impeller with Guidevane

2005 ◽  
Author(s):  
Takuji Tsugawa
Keyword(s):  
Velocity Ratio ◽  
Optimum Shape ◽  
Hydraulic Efficiency ◽  
Mixed Flow ◽  
Shape Factors ◽  
Flow Angle ◽  
Multi Stage ◽  
Absolute Flow ◽  
Specific Speed

In the previous paper, the optimum meridian profile of impeller was obtained for various specific speed by means of eight shape factors, that is, inlet relative flow angle β1, turning angle Δβ, axial velocity ratio kc = Cm2/Cm1, impeller diameter ratio kd = D1c/D2c, outlet hub-tip ratio ν2, tip solidity σtimp, mid span solidity σcimp and hub solidity σhimp. In this paper, the optimum meridian profile of multi-stage impeller with guidevane was obtained by means of twelve shape factors. The additional four shape factors are guidevane tip solidity σtgv, mid span solidity σcgv, hub solidity σhgv and coefficient of peripheral velocity at impeller inlet or guidevane outlet kCu1c. In the optimum method, the hydraulic efficiency and suction specific speed are calculated by diffusion factor. In the optimum condition, the best hydraulic efficiency or the best suction specific speed is obtained. In the cyclic flow condition of multi-stage impeller with guidevane, the absolute flow velocity of guidevane outlet is equal to that of impeller inlet, and the diameter of guidevane outlet is equal to that of impeller inlet. In this calculation, the diameter of impeller outlet is equal to that of guidevane inlet. The total calculation number of case study is very large, so the number of each parameter is about between four and seven. The best 1000 optimum meridian profiles and the best design parameter are selected for few kinds of specific speed using twelve dimensional optimum method. As the result of this calculation, the optimum meridian profile of multi-stage impeller and guidevane. The more detailed optimum multi-stage mixed flow impeller and guidevane profile is drawn. For, example, the 1000 specific speed is selected for case study of multi-stage mixed flow impeller. At first, the approximate optimum shape factors are present shape factors. And the optimum shape factors which have better efficiency are tried to find near the present shape factors. Then the study of shape factor changes is the objective of this paper.

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