scholarly journals Development and Numerical Performance Analysis of a Pump Directly Driven by a Hydrokinetic Turbine

Energies ◽  
2019 ◽  
Vol 12 (22) ◽  
pp. 4264
Author(s):  
Daqing Zhou ◽  
Huixiang Chen ◽  
Yuan Zheng ◽  
Kan Kan ◽  
An Yu ◽  
...  
Keyword(s):  
Centrifugal Pump ◽  
Degrees Of Freedom ◽  
Draft Tube ◽  
Model Tests ◽  
Cross Sectional ◽  
Practical Applications ◽  
Plain Area ◽  
Pump Head ◽  
Cfd Method ◽  
River Current

Marine and hydrokinetics (MHK) represent an emerging industry with hundreds of potentially viable technologies, such as potential extractable energy from plain area rivers where the water level differences are very small and the traditional water turbine pump (WTP) cannot be used. A suitable WTP, composed of a tubular turbine directly driving a centrifugal pump, was designed and developed based on computational fluid dynamics (CFD) and model tests. Two general design schemes of such river-current (RC)-driven WTP are presented here, obtaining the desired operating parameters of discharge and pump head. A CFD analysis of Scheme B, which employs a radial outlet, allowing additional degrees of freedom for the dimensions of the centrifugal pump, was carried out and verified experimentally by model tests. The minimum deviation of pump head is within ±5%, and the trend of other working conditions is consistent, so the results of the numerical simulation and model tests show good agreement, demonstrating the feasibility of the CFD method for practical applications. Then, using the CFD method, the optimum rotational speed for the turbine was determined, and the turbine draft tube was improved further. With a turbine runner diameter of 0.5 m, the results show best performance at n = 350 r/min. The straight conical draft tube was changed to an elbow draft tube with multiple exits. Additionally, four different cross-sectional shapes were designed for the pump volute, and their effects on the performance of the WTP were analyzed. Finally, the round shape was selected, because of its best performance. The turbine unit has the highest efficiency of 81.2%, at an inlet velocity v = 2.4 m/s, while the pump exhibits the best efficiency of 90.2% at the design discharge and head of 30 l/s and 4.45 m respectively. Overall, the RC-driven WTP makes good use of the kinetic energy of the river current as a power source, solving the inapplicability of traditional WTP in plain areas.

Modeling Viscous Oil Cavitating Flow in a Centrifugal Pump

2015 ◽  
Vol 138 (1) ◽  
Author(s):  
Wen-Guang Li
Keyword(s):  
Centrifugal Pump ◽  
Volume Ratio ◽  
Cavitating Flow ◽  
Liquid Volume ◽  
Cavitation Model ◽  
Gas Concentration ◽  
Noncondensable Gas ◽  
Cavitation Performance ◽  
Pump Head ◽  
Cfd Method

Properly modeling cavitating flow in a centrifugal pump is a very important issue for prediction of cavitation performance in pump hydraulic design optimization and application. As a first trial, the issue is explored by using computational fluid dynamics (CFD) method plus the full cavitation model herein. To secure a smoothed head-net positive suction head available (NPSHa) curve, several critical techniques are adopted. The cavitation model is validated against the experimental data in literature. The predicted net positive suction head required (NPSHr) correction factor for viscosity oils is compared with the existing measured data and empirical correlation curve, and the factor is correlated to impeller Reynolds number quantitatively. A useful relation between the pump head coefficient and vapor plus noncondensable gas-to-liquid volume ratio in the impeller is obtained. Vapor and noncondensable gas concentration profiles are illustrated in the impeller, and a “pseudocavitation” effect is confirmed as NPSHa is reduced. The effects of exit blade angle on NPSHr are presented, and the contributions of liquid viscosity and noncondensable gas concentration to the increase of NPSHr at a higher viscosity are identified.

scholarly journals Numerical Investigation on the Mechanism of Double-Volute Balancing Radial Hydraulic Force on the Centrifugal Pump

Processes ◽  
2019 ◽  
Vol 7 (10) ◽  
pp. 689
Author(s):  
Yuan ◽  
Yuan ◽  
Tang
Keyword(s):  
Centrifugal Pump ◽  
Cross Sections ◽  
Performance Test ◽  
Flow Characteristics ◽  
Radial Force ◽  
Transient Pressure ◽  
Force Magnitude ◽  
Hydraulic Force ◽  
Pump Head ◽  
Cfd Method

Double-volute is an effective technique to reduce radial hydraulic force on the centrifugal pump and thereby mitigate the pump-casing vibration induced by unsteady flow characteristics. The mechanism of the double-volute structure balancing radial force on the impeller and volute was investigated on the basis of volute cross-sections by using Computational Fluid Dynamics (CFD) method. The tested performances and simulated inner-flow characteristics of two pumps with single-volute and double-volute were compared in this paper. The performance-test results verify the veracity of CFD method and illustrate that double-volute pump has some losses in terms of pump head and operation efficiency. The numerical simulations reveal that double-volute pump has smaller radial-force magnitude than single-volute pump on the abnormal conditions. Steady pressure field and transient pressure variations of pumps were explored to account for radial-force characteristics of double-volute pump. Compared with the single-volute structure, obvious pressure increases were found in the upper chamber (single part) of the double-volute, while the static pressure decreased in the lower chamber (double chambers). This situation reduces the pressure difference between two volute cross-sections in the collinear radial direction, resulting in smaller radial hydraulic force. Moreover, the transient simulations present the same phenomenon. The radial-forces distribute more uniformly in the double-volute pump, which can alleviate some vibrations.

Diagnostics of metal samples using the results of experimental and theoretical study of positively charged microparticles formed upon sample destruction

2018 ◽  
Vol 84 (10) ◽  
pp. 23-28
Author(s):  
D. A. Golentsov ◽  
A. G. Gulin ◽  
Vladimir A. Likhter ◽  
K. E. Ulybyshev
Keyword(s):  
Experimental Data ◽  
Early Stage ◽  
Experimental Studies ◽  
Material Model ◽  
Total Charge ◽  
Cross Sectional ◽  
Practical Applications ◽  
Mechanical And Electrical Properties ◽  
Order Of Magnitude ◽  
Using Data

Destruction of bodies is accompanied by formation of both large and microscopic fragments. Numerous experiments on the rupture of different samples show that those fragments carry a positive electric charge. his phenomenon is of interest from the viewpoint of its potential application to contactless diagnostics of the early stage of destruction of the elements in various technical devices. However, the lack of understanding the nature of this phenomenon restricts the possibility of its practical applications. Experimental studies were carried out using an apparatus that allowed direct measurements of the total charge of the microparticles formed upon sample rupture and determination of their size and quantity. The results of rupture tests of duralumin and electrical steel showed that the size of microparticles is several tens of microns, the particle charge per particle is on the order of 10–14 C, and their amount can be estimated as the ratio of the cross-sectional area of the sample at the point of discontinuity to the square of the microparticle size. A model of charge formation on the microparticles is developed proceeding from the experimental data and current concept of the electron gas in metals. The model makes it possible to determine the charge of the microparticle using data on the particle size and mechanical and electrical properties of the material. Model estimates of the total charge of particles show order-of-magnitude agreement with the experimental data.

Effect of semi-open impeller side clearance on centrifugal pump cavitation inception

2018 ◽  
Vol 1 (2) ◽  
pp. 24-39
Author(s):  
A. Farid ◽  
A. Abou El-Azm Aly ◽  
H. Abdallah
Keyword(s):  
Centrifugal Pump ◽  
Static Pressure ◽  
Rotation Speed ◽  
Centrifugal Pumps ◽  
Severe Condition ◽  
Cavitation Inception ◽  
Total Input ◽  
Input Pressure ◽  
Pump Head ◽  
Pump Pressure

Cavitation in pumps is the most severe condition that centrifugal pumps can work in and is leading to a loss in their performance.  Herein, the effect of semi-open centrifugal pump side clearance on the inception of pump cavitation has been investigated.  The input pump pressure has been changed from 80 to 16 kPa and the pump side clearance has been changed from 1 mm to 3 mm at a rotation speed of 1500 rpm. It has been shown that as the total input pressure decreased; the static pressure inside the impeller is reduced while the total pressure in streamwise direction has been reduced, also the pump head is constant with the reduction of the total input pressure until the cavitation is reached. Head is reduced due to cavitation inception; the head is reduced in the case of a closed impeller with a percent of 1.5% while it is reduced with a percent of 0.5% for pump side clearance of 1mm, both are at a pressure of 20 kPa.   Results also showed that the cavitation inception in the pump had been affected and delayed with the increase of the pump side clearance; the cavitation has been noticed to occur at approximate pressures of 20 kPa for side clearance of 1mm, 18 kPa for side clearances of 2mm and 16 kPa for 3mm.

Systematic Synthesis and Applications of Novel Multi-Degree-of-Freedom Differential Systems

1992 ◽  
Author(s):  
Sridhar Kota ◽  
Srinivas Bidare
Keyword(s):  
Degrees Of Freedom ◽  
Building Blocks ◽  
Degree Of Freedom ◽  
Differential Systems ◽  
Practical Applications ◽  
Epicyclic Gear ◽  
Differential Mechanism ◽  
Long Time ◽  
Gear Trains ◽  
Drive Systems

Abstract A two-degree-of-freedom differential system has been known for a long time and is widely used in automotive drive systems. Although higher degree-of-freedom differential systems have been developed in the past based on the well-known standard differential, the number of degrees-of-freedom has been severely restricted to 2n. Using a standard differential mechanism and simple epicyclic gear trains as differential building blocks, we have developed novel whiffletree-like differential systems that can provide n-degrees of freedom, where n is any integer greater than two. Symbolic notation for representing these novel differentials is also presented. This paper presents a systematic method of deriving multi-degree-of-freedom differential systems, a three and four output differential systems and some of their practical applications.

scholarly journals Program Quality and Developmental Outcomes Related to Youth Volleyball in Ethiopia: Assessing Relationships and Variations

2021 ◽  
Vol 11 (4) ◽  
pp. 1388-1405
Author(s):  
Abdulaziz Mussema ◽  
Tefera Tadesse ◽  
Zelalem Melkamu
Keyword(s):  
Developmental Outcomes ◽  
Central Zone ◽  
Youth Sport ◽  
Program Quality ◽  
Cross Sectional Survey ◽  
Cross Sectional ◽  
Practical Applications ◽  
The Mean ◽  
Project Site

This study aims to assess program quality and developmental outcomes of a youth volleyball project in one of the regional states in Ethiopia, and further examine variations between groups across gender and project site zones. We applied a cross-sectional survey design, collecting quantitative data from youth volleyball players (n = 215) with a mean age of 16.18 years (SD = 0.69) through a self-reported questionnaire. The results indicated that young players’ perceptions did not vary significantly across gender, except for the mean score of the perceived experience variable for girls (M = 2.68, SD = 0.318) was significantly higher than the mean score of boys (M = 2.58, SD = 0.258). One-way (project site zone) analyses of variance (ANOVAs) identified that youth volleyball projects in the central zone were consistently rated higher than those in the western zone, except for the current practice rating. Moreover, correlation analysis results indicated the presence of a significant relationship, both within and between program quality and developmental outcome variables. Furthermore, the results of regression analysis indicated that the program quality variables together predicted each of the developmental outcomes, accounting for 18.9% to 31.7% of the variances. It is concluded that the quality of the youth volleyball program in Ethiopia varies considerably across the project site zones and the program quality variables significantly relate to the developmental outcomes measured with differential effects. The data from this study reveals several practical applications for Ethiopia and beyond in terms of guiding youth volleyball projects. Moreover, the findings of the study showed that youth sport and the manner in which it is structured and delivered to youth players influences the attainment of positive developmental outcomes. These results suggest that contextual differences really do have an effect on the quality of youth sport program processes and developmental outcomes.

scholarly journals ANALISA PERHITUNGAN DAYA POMPA SENTRIFUGAL DI GEDUNG UNIVERSITAS 17AGUSTUS 1945 JAKARTA

2019 ◽  
Vol 4 (1) ◽  
pp. 7-14
Author(s):  
M Fajri Hidayat ◽  
Nor Fajri
Keyword(s):  
Pump Power ◽  
Centrifugal Pump ◽  
Water Requirement ◽  
Clean Water ◽  
Pump Head ◽  
Pump Shaft ◽  
Specific Speed

AbstrakPompa adalah suatu alat atau mesin untuk memindahkan cairan dari satu tempat ketempat lain melalui suatu media perpipaan dengan cara menambahkan energi pada cairan yang dipindahkan dan berlangsung secara terus menerus. Pompa yang digunakan dalam analisa ini yaitu Pompa Sentrifugal yang terdapat di gedung Universitas 17 Agustus 1945 Jakarta. Tujuan dari analisa ini yaitu untuk mengetahui kebutuhan air pada gedung Universitas 17 Agustus 1945 Jakarta. Kebutuhan air pada gedung Universitas 17 Agustus 1945 Jakarta dihitung berdasarkan luas lantai gedung dan pemakaian setiap dosen, karyawan, mahasiswa, dan rektorat di Universitas 17 Agustus 1945 Jakarta. Hasil analisa di dapatkan total kebutuhan air bersih pada gedung Universitas 17 Agustus 1945 Jakarta adalah 1.7910 Liter/hari. Kapasitas pompa sebesar 0.06 m3/s. Head total pompa sebesar 31.99 m. Putaran poros pompa yaitu 1500 rpm. Daya pompa sebesar 0.817 kW. Kecepatan spesifik sebesar 48.51 rpm. Dari hasil analisa dapat dinyatakan bahwa Pompa Sentrifugal yang berada di gedung Universitas 17 Agustus 1945 Jakarta sudah layak untuk digunakan. Kata Kunci : Kebutuhan air, kapasitas pompa, pompa sentrifugal Abstract          A pump is a device or a machine to move liquids from one place to another via a piping medium by adding energy to the fluid that is moved and continuous. The pump used in this analysis is the Centrifugal Pump contained in the building University 17 August 1945 Jakarta. The purpose of this analysis is to determine the needs of water in the building University 17 August 1945 Jakarta. Water requirement at University building August 17, 1945 Jakarta is calculated based on building floor and usage of every lecturer, staff, student, and rectorate in University 17 August 1945 Jakarta. The result of the analysis in obtaining the total clean water requirement at the building University 17 August 1945 Jakarta is 1.7910 Liter / day. The pump capacity is 0.06 m3 / s. The total pump head is 31.99 m. The rotation of the pump shaft is 1500 rpm. The pump power is 0.817 kW. Specific speed of 48.51 rpm. The results of the analysis can be stated that the Centrifugal Pump located in the building University 17 August 1945 Jakarta is feasible to use. Keywords : Water requirement, pump capacity, centrifugal pump

Model Tests for Safe-Return-to-Port of a Damaged Ship in Waves

2015 ◽  
Author(s):  
Jeonghwa Seo ◽  
Cristobal Santiago Bravo ◽  
Shin Hyung Rhee
Keyword(s):  
Degrees Of Freedom ◽  
Feedback System ◽  
Model Tests ◽  
Measurement Unit ◽  
Test Model ◽  
Motion Response ◽  
Six Degrees Of Freedom ◽  
Heading Angle ◽  
Wave Conditions ◽  
Damaged Ship

A series of tests using a course-keeping model ship with an autopilot system were carried out in a towing tank for research on Safe-Return-to-Port (SRTP). The autopilot system controls the rudder angle and propeller revolution rate by a feedback system. The variation of the heading angle of the test model with different control parameters was investigated first, to ensure that the test model had sufficient course-keeping maneuverability in severe wave conditions. The wave conditions and propeller revolution rate were selected based on SRTP regulations. Tests were conducted in wave conditions corresponding to sea states 4 to 6. The six-degrees-of-freedom motion response of the test model was measured by a wireless inertial measurement unit and gyro sensors to achieve fully wireless model tests. The advance speed and motion response in various wave conditions were measured and analyzed to investigate the effects of flooding behavior in a damaged condition and of waves on the propulsion and maneuvering performance of the damaged ship model.

Anthropometry-Based Surface Modeling of the Human Torso

1994 ◽  
Author(s):  
Peng Li ◽  
Peter R. M. Jones
Keyword(s):  
Human Body ◽  
Computer Aided Design ◽  
Three Dimensional ◽  
Human Growth ◽  
Surface Model ◽  
Cross Sectional ◽  
Practical Applications ◽  
Garment Design ◽  
Aided Design ◽  
Reference Body

Abstract There is an increasing need for computerized surface model of the human body in human growth, garment design and ergonomics. However, there is a shortage of three-dimensional (3-D) models of the human body in practical applications. This paper presents a new approach for constructing a 3-D surface model of the human torso using anthropometry. The torso is created by from a reference body of average shape which is represented by a family of cross-sectional curves. The shape and size of the reference body can be modified according to anthropometric data. This approach has been implemented on a personal computer. The resulting 3-D model is a parametric surface based on non-uniform B-splines and can easily be exported to other computer aided design applications.

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