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Design And Analysis Of CentrifugalPump

GUIDED BY:

Assistant ProfessorJayendra B. Patel

PRESENTED BY:

Makwana Hardik

Modh Hiren

Patel Gaurang

Patel Dhaval

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Introduction

• It Convert the mechanical energy into hydraulic energy bycentrifugal 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 isdeveloped partly by centrifugal force and partly by the lift of thevanes of the impeller on the liquid.

• Axial Flow -A centrifugal pump in which the pressure isdeveloped by the propelling or lifting action of the vanes of theimpeller 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 impellerand thrown outward by centrifugal force

• The conversion of kinetic energy into pressure energy suppliesthe pressure difference between the suction side and deliveryside of the pump

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• Components of centrifugal pump

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• Shaft

• Impeller

• Casing

• Suction and discharge nozzle

• Bearing housing

• Seal Chamber and Stuffing Box

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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.

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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.

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• Casing

• Casings are generally of two types: volute and circular. Theimpellers are fitted inside the casings.

• Volute casings build a higher head; circular casings are usedfor low head and high capacity.

• Circular casing have stationary diffusion vanes surroundingthe impeller periphery that convert velocity energy to pressureenergy.

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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.

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• Advantages and disadvantages of centrifugalpump

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 ofconditions

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• 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

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2.Wear of the Impeller can be worsened by

suspended solids

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

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Wen-Guang Li:-

• centrifugal pump performances are tested by usingwater and viscous oil as working fluids whose kinematicviscosity is 1 and 48 mm2/s, respectively,

• The flows in the centrifugal pump impeller are alsomeasured accurately by using a two-dimensional LDV inbest efficiency and part-loading points as the pumphandling two kinds of the working fluids.

• The effects of the viscosity on the performance andflow pattern within the impeller are investigated basedon the experimental results.

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• The high viscosity results in rapid increases in the discfriction losses over outsides of the impeller shroud andhub as well as the hydraulic losses in flow channels ofthe pump.

• The flow patterns near the impeller outlet are littleaffected by the viscosity of the fluids, but those nearthe impeller inlet are greatly affected by the viscosity.

• There is a wide wake near the blade suction side of thecentrifugal pump impeller.

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• 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.

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• 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.

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John S. Anagnostopoulos:-

• After estimating the additional hydraulic losses in thecasing and the inlet and outlet sections of the pump, theperformance of the pump can be predicted using thenumerical results from the impeller section only.

• The regulation of various energy loss coefficients involvedin the model pump.

• The predicted overall efficiency curve of the pump wasfound to agree very well with the correspondingexperimental data.

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• 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.

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M.H. Shojaeefard, M. Tahani, M.B. Ehghaghi, M.A.Fallahian, M. Beglari:-

• Research on Numerical study of the effects of somegeometric characteristics of a centrifugal pumpimpeller that pumps a viscous fluid

• The performance of centrifugal pumps drops sharplyduring the pumping of viscous fluids. Changing somegeometric characteristics of the impeller in these typesof pumps improve their performance.

• In this investigation, the 3-D flow in centrifugal pumpalong with the volute has been numerically simulated.

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• This numerical solution has been carried out for differentcases of primary geometry, and for the changes made tothe outlet angle and passage width of the impeller, and alsofor simultaneous modifications of these parameters.

• The flow analysis indicates that with the modification of theoriginal geometry of the pump, at the 30 outlet angle andthe passage width of 21 mm, the pump head and efficiencyincreases compared to the other cases; this improvement isdue the reduction of losses arising from the generation ofeddies in the passage and outlet of the impeller.

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• Drawing of impeller

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• Drawing of casing

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• Original shape of impeller

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• Original shape of casing

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• Fluid model of impeller

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• Fluid model of casing

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• 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.

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• 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

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• 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.

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• Mesh reportMesh Information for CFX

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Domain Nodes Elements

casing 768747 4094405

impeller 109653 571652

solid 1234 5337

All domains 879634 4671394

• Meshing of

centrifugal

pump casing

• Meshing of

impeller of

centrifugal

pump32

• 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.

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• 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 massflow rate and pressure. Therefore in the Postprocessing velocity contours, pressure contours andmass flow rate are studied for each case.

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• 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 m3/s

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• 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

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• 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

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• Total pressure inside the centrifugal pump

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‹#›

• Reference1. 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.

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Thank you

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