Design And Analysis Of Centrifugal Pump GUIDED BY: Assistant Professor Jayendra B. Patel PRESENTED BY: Makwana Hardik Modh Hiren Patel Gaurang Patel Dhaval 1
Introduction It Convert the mechanical energy into hydraulic energy by centrifugal force on the liquid Used to move liquids through a piping system Components: 1. Stationary componets, casing, casing cover and bearings 2. Rotating components, impeller and shaft Classification: Radial Flow -A centrifugal pump in which the pressure is developed wholly by centrifugal force. Mixed Flow -A centrifugal pump in which the pressure is developed partly by centrifugal force and partly by the lift of the vanes of the impeller on the liquid. Axial Flow -A centrifugal pump in which the pressure is developed by the propelling or lifting action of the vanes of the impeller on the liquid. 2
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Working Simplest piece of equipment in any process plant Energy changes occur by virtue of impeller and volute Liquid is fed into the pump at the center of a rotating impeller and thrown outward by centrifugal force The conversion of kinetic energy into pressure energy supplies the pressure difference between the suction side and delivery side of the pump 4
Components of centrifugal pump 5
Shaft Impeller Casing Suction and discharge nozzle Bearing housing Seal Chamber and Stuffing Box 6
1.Shaft The basic purpose of a centrifugal pump shaft is to transmit the torques encountered when starting and during operation while supporting the impeller and other rotating parts. Pump shafts are usually protected from erosion, corrosion, and wear at the seal chambers, leakage joints, internal bearings, and in the waterways by renewable sleeves. 7
2.Impeller The impeller is the main rotating part that provides the centrifugal acceleration to the fluid. Closed impellers require wear rings and these wear rings present another maintenance problem. Open and semi-open impellers are less likely to clog, but need manual adjustment to the volute or back-plate to get the proper impeller setting and prevent internal re-circulation. 8
Casing Casings are generally of two types: volute and circular. The impellers are fitted inside the casings. Volute casings build a higher head; circular casings are used for low head and high capacity. Circular casing have stationary diffusion vanes surrounding the impeller periphery that convert velocity energy to pressure energy. 9
Suction and discharge nozzle 1. End suction/top discharge- The suction nozzle is located at the end of and concentric to the shaft. This pump is always of an overhung type and typically has lower NPSH because the liquid feeds directly into the impeller eye. 2. Top suction Top discharge nozzle -The suction and discharge nozzles are located at the top of the case perpendicular to the shaft. This pump can either be an overhung type or between-bearing type but is always a radial split case pump. 3. Side suction / Side discharge nozzles - The suction and discharge nozzles are located at the sides of the case perpendicular to the shaft. This pump can have either an axially or radial split case type. 10
Advantages and disadvantages of centrifugal pump Advantages Simple in construction and cheap Handle liquid with large amounts of solids No metal to metal fits No valves involved in pump operation Maintenance costs are lower Disadvantages Cannot handle highly viscous fluids efficiently Cannot be operated at high heads Maximum efficiency holds over a narrow range of conditions 11
Problems of centrifugal pumps 1.Cavitations the NPSH of the system is too low for the selected pump Reduces the pump capacity Causes : metal removal reduced flow loss in efficiency and noise To avoid cavitation NPSH 12
2.Wear of the Impeller suspended solids can be worsened by 3.Corrosion inside the pump caused by the fluid properties 4.Overheating due to low flow 5.Leakage along rotating shaft 6.Lack of prime centrifugal pumps must be filled (with the fluid to be pumped) in order to operate 7.Surge 13
Wen-Guang Li:- centrifugal pump performances are tested by using water and viscous oil as working fluids whose kinematic viscosity is 1 and 48 mm 2 /s, respectively, The flows in the centrifugal pump impeller are also measured accurately by using a two-dimensional LDV in best efficiency and part-loading points as the pump handling two kinds of the working fluids. The effects of the viscosity on the performance and flow pattern within the impeller are investigated based 14
The high viscosity results in rapid increases in the disc friction losses over outsides of the impeller shroud and hub as well as the hydraulic losses in flow channels of the pump. The flow patterns near the impeller outlet are little affected by the viscosity of the fluids, but those near the impeller inlet are greatly affected by the viscosity. There is a wide wake near the blade suction side of the centrifugal pump impeller. 15
Slawomir Dykas And Andrzej Wilk:- Research on the flow characteristic of a high- rotational centrifugal pump by means of CFD method numerical analysis of the flow through a centrifugal pump working at high rotational speed. This kind of a pump is characterized by a high delivery head and a low discharge. The considered pump is a one-stage centrifugal pump with a rotational speed of 12000 rpm. 16
The main purpose of the presented research has been to determine the flow characteristic of the pump by means of CFD methods. To this end the commercial CFD code, ANSYS CFX 13, has been used. The obtained numerical results have shown high usefulness of the CFD methods for the flow machinery design process. In the next step the obtained flow characteristic will be compared with the experimental investigations. 17
John S. Anagnostopoulos:- After estimating the additional hydraulic losses in the casing and the inlet and outlet sections of the pump, the performance of the pump can be predicted using the numerical results from the impeller section only. The regulation of various energy loss coefficients involved in the model pump. The predicted overall efficiency curve of the pump was found to agree very well with the corresponding experimental data. 18
Finally, a numerical optimization algorithm based on the unconstrained gradient approach is developed and combined with the evaluation software in order to find the impeller geometry that maximizes the pump efficiency, using as free design variables the blade angles at the leading and the trailing edge. The results verified that the optimization process can converge very fast and to reasonable optimal values. 19
M.H. Shojaeefard, M. Tahani, M.B. Ehghaghi, M.A. Fallahian, M. Beglari:- Research on Numerical study of the effects of some geometric characteristics of a centrifugal pump impeller that pumps a viscous fluid The performance of centrifugal pumps drops sharply during the pumping of viscous fluids. Changing some geometric characteristics of the impeller in these types of pumps improve their performance. In this investigation, the 3-D flow in centrifugal pump along with the volute has been numerically simulated. 20
This numerical solution has been carried out for different cases of primary geometry, and for the changes made to the outlet angle and passage width of the impeller, and also for simultaneous modifications of these parameters. The flow analysis indicates that with the modification of the original geometry of the pump, at the 30 outlet angle and the passage width of 21 mm, the pump head and efficiency increases compared to the other cases; this improvement is due the reduction of losses arising from the generation of eddies in the passage and outlet of the impeller. 21
Drawing of impeller 22
Drawing of casing 23
Original shape of impeller 24
Original shape of casing 25
Fluid model of impeller 26
Fluid model of casing 27
Simulation of centrifugal pump CFD It would be particularly helpful for modifying or improving the existing designs of the centrifugal pump. Simulation facilitated to reduce cost and time of the experiment. If once centrifugal pump is simulated then it would be easy to check the performance of the centrifugal pump at any condition. Computational fluid dynamics is the branch of engineering used for solution of problem related to fluid dynamics, heat transfer, hydraulics machines such as pumps, turbines and have many more applications in engineering. 28
GENERATION OF FLUID MODEL Fluid model is considered for numerical solution. Fluid model is having different topology compared to actual model. This fluid model is generated using software ANSYS 13.0 Fluid model for one centrifugal pump with specific speed 53.87rpm 29
MESHING OF FLUID MODEL In the numerical solution the working domain is divided into small sub domains. These sub domains are called as mesh. Governing equations are then descretised and solved in each of these sub domains. There are two types of mesh; structured and unstructured. A structured mesh is characterized by regular connectivity that can be expressed as a two or three dimensional array. An unstructured mesh is characterized by irregular connectivity is not readily expressed as a two or three dimensional array in computer memory. 30
Mesh report Mesh Information for CFX Domain Nodes Elements casing 768747 4094405 impeller 109653 571652 solid 1234 5337 All domains 879634 4671394 31
Meshing of centrifugal pump casing Meshing of impeller of centrifugal pump 32
Steps performed in CFX while solving the fluid centrifugal pump models. Step 1 flow analysis for given fluid model steady state analysis type is considered. Present fluid model has two fluid domains i.e. impeller and casing. For casing, stationary domain motion is considered. For impeller, rotating type domain motion is considered. Step 2 interface conditions First interface is defined in between casing and impeller. In this outlet of casing and inlet of impeller are interfaced to each other. In this interface impeller has rotating motion whereas casing is stationary part, so frozen rotor is considered for mixing model. 33
Step 3 Solver. In basic solver controls, high resolution for advection term and first order turbulence numeric is considered. In fluid time scale controls, physical time scale controls are taken as per calculations Step 4 Post processing Given fluid model has constant speed, varying mass flow rate and pressure. Therefore in the Post processing velocity contours, pressure contours and mass flow rate are studied for each case. 34
Result and conclusion:- Centrifugal pump of 53.83rpm specific speed is simulated for constant speeds of 1400rpm with variation in mass flow rate and pressure. Hex dominant mesh structure is used with 879634 node points and 4671394 elements for this centrifugal pump. After simulation of centrifugal pump result is that the mass flow rate is constant with the value of 0.118 m 3 /s 35
Pressure is maximum at suction eye which is shown in red color and minimum at volute casing which shown in green color Here red color denote maximum pressure and green color denote minimum pressure 36
Velocity is minimum at suction eye which is shows in blue color and maximum at volute casing and is shown in red color Minimum pressure is shown in blue color and maximum pressure is shown in red color 37
Total pressure inside the centrifugal pump 38
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Reference 1. John Richards (1894). Centrifugal pumps: an essay on their construction and operation, and some account of the origin and development in this and other countries. The Industrial Publishing Company. pp. 40 41. 2. Igor, J., Joseph, P., and Charles, C. 2001. Pump Hand Book. USA: McGraw-Hill Company. 3. Baha Abulnaga (2004). Pumping Oil sand Froth. 21st International Pump Users Symposium, Baltimore, Maryland. Published by Texas A&M University, Texas, USA. 4. Acosta, A.J., 1954. An experimental and theoretical investigation of two-dimensional centrifugal pump impellers. 5. Larry Bachus., and Angel Custodio. 2003. Known and Understand Centrifugal Pump. Japan: Bachus Company. Tokyo 113. 40
Thank you 41