Design Impeller Using Solidworks And Cfd.pdf

See discussions, stats, and author profiles for this publication at: https://www.researchgate.net/publication/285055176

Design and development of centrifugal pump impeller for performance enhancement Technical Report · November 2015 DOI: 10.13140/RG.2.1.4023.4329

CITATIONS

READS

0

13,864

1 author: Mohamad hazeri Ismail Universiti Malaysia Pahang 5 PUBLICATIONS   1 CITATION    SEE PROFILE

All content following this page was uploaded by Mohamad hazeri Ismail on 29 November 2015. The user has requested enhancement of the downloaded file.

Design and development of centrifugal pump impeller for performance enhancement M.Hazeri Ismail Faculty of Mechanical Engineering, Universiti Malaysia Pahang (UMP), 26600 Pekan, Pahang, Malaysia, Phone: +0199947294 Email: [email protected]

ABSTRACT There is an ever increasing use of centrifugal pumps in applications which require the pumping of liquids containing solids, and liquids other than water. The application in industry nowadays such as oil and gas with the increasing use of centrifugal pumps for applications of this type, it becomes important to be able to predict pump characteristics and create efficient design. Design changes will be suggested in an attempt to improve the performance of the impeller used in the pump. This project consists of the detailed study of a model of the centrifugal pump and also consists of the detailed to identify, observe and determine the pattern of velocity profile and pressure distribution by using CFD simulation program. This project will definitely provide much helpful information while contributing to the knowledge about the design and characteristics of centrifugal pumps. Keywords: impeller; centrifugal pump design; pump performance; CFD Analysis; Simulation ANSYS

INTRODUCTION A pump is a mechanical device for moving a fluid from a lower to a higher location, or from a lower to a higher pressure area. Mechanical energy will be given to the pump and it later converted into hydraulic energy of fluid. Pumps produce negative pressure at the pressure at the inlet so that the atmospheric pressure pushes the fluid towards the pump[1, 2]. The fluid coming into the pump is pushed towards the outlet mechanically where positive pressure is generated. Pumps are classified in number of the ways based on their purpose, specifications, design, environment etc.[3]. The fluid enters the pump impeller along or near to the rotating axis and is accelerated by the impeller, flowing radially outward or axially into a diffuser or volute chamber, from where it exits into the downstream piping system. Centrifugal pumps are typically used for large discharge through smaller heads[1, 4].

Figure 1: Liquid flow path inside a centrifugal pump

Computational fluid dynamics (CFD) analysis is being increasingly applied in the design of centrifugal pumps. With the aid of the CFD approach, the complex internal flows in water pump impellers, which are not fully understood, can be well predicted, to speed up the pump design procedure[5, 6]. Thus, CFD is any important tool for pump designers. The use of CFD tools in turbo machinery industry is quite common today. Recent advances in computing power, together with powerful graphics and interactive 3D manipulation of models have made the process of creating a CFD model and analysing results much less labour intensive, reducing time and, cost. As a result of these factors, Computational Fluid Dynamics is now an established industrial design tool, helping to reduce design time scales and improve processes throughout the engineering world [7].

EXPERIMENTAL SETUP Centrifugal pump design The design of centrifugal pump is focus to Impeller Design. The detailed procedure of impeller design can be found in different literature; in this paper for the design of centrifugal pump, the design parameters and specification has be given in table 1. Table 1: Design speciation No 1 2 3 4 5 6 7 8 9 10 11 12 13

parameters Specific speed Power input to the pump Shaft diameter Hub diameter Outer diameter of impeller Velocity of fluid at the impeller inlet Eye diameter of impeller Inner diameter of impeller Inlet blade angle Impeller outlet area Impeller width at inlet Blade angle at outlet Number of blades

model 973 rpm 15.21 hp 17.69 mm 25 mm 0.2 m 4.103 m/s 76 mm 74 mm 20.3 degree 5943.5 mm2 9.905 mm 24 degree 6

Experimental Procedure Three-dimensional model of an impeller was first created in Solid works 2014 software and exported into STEP files. The STEP files were then imported into fluid flow simulation, the mesh generator[5, 8]. The fluid volume was split into a rotating fluid volume, a scroll volume, an inlet cone volume, and an inlet/outlet duct volume. The inlet and outlet ducts were intentionally set to simulate the actual measuring situation and to provide better boundary conditions for simulations [1, 9]. The flow was assumed fully developed when leaving the inlet and outlet ducts. The impeller wheel volume was defined as a rotating reference frame with constant speed, and other blocks were defined in a stationary frame. This setup is referred to as a frozen rotor model[10].

Figure 2: impeller 3D solid works Solution initialization Initialization in Ansys is done by give initial guess values to solve the governing equation so that the flow field variables can be solved by iteration toward the solution. The default automatic initialization for the velocity and static pressure is used to provide a start point to the solution[7]. Analysis setup Design points for a parametric study can be specified using the required duty of the pump in the setup steps: Input Material: Material is also assigned to the parts of the pump as: Casing and Impeller (Aluminium alloy), Hydraulic Region (Water), Rotating part (Rotating region) Boundary Conditions: Boundary conditions are applied to the inlet and outlet of the pump i.e. Velocity of fluid at the impeller inlet 4.103 m/s, and Specific speed 973 rpm.

MATHEMATICAL MODELLING Performance parameter Efficiency, head, capacity, power, net positive suction head, and specific speed are parameters that have describe a centrifugal pump performance. These parameters will be discussed in the following sections. The head (H) is the net work done on a unit weight of water by the pump[11]. It is given by

H=

d

-

s

(1)

The power imparted to the water by the pump is called water power. Equation below is used to compute water power (WP)

WP = (

(2)

Pump efficiency (Ep) is the per cent of power input to the pump shaft (the brake power) that is transferred to the water. Ep can be computed using Equation below

Ep = 100(

(3)

Specific speed (Ns) is an index to pump performance derived using dimensional analysis. It consolidates a pumps speed, design capacity, and head into one term. Ns is computed from

Ns =

(4)

RESULTS AND DISCUSSION CFD RESULTS After analysis has been implemented the following results are obtained. The results are taken only when the convergence is obtained for the solution. As the solution iterated 1000 times and the pump impeller completed a full turn. Following results are taken from different axis and cross-sections.

Figure 3: Experiment result (a) Efficiency diagram (b) pressure diagram

Figure 3: Experiment result (a) velocity diagram (b) flow diagram

CONCLUSIONS Pump impeller is designed for the given specification and numerical analysis is carried out in fluid flow simulation package. Contour plots are also obtained for the distribution of static pressure, velocity and wall shear stress. From that the design and analysis methods lead to completely very good flow field predictions. This makes the methods useful for general performance prediction. In this way, the design can be optimized to give reduced energy consumption, lower head loss, prolonged component life and better flexibility of the system, before the prototype is even built.

REFERENCE 1.

2.

3.

4.

5. 6. 7. 8. 9.

10. 11.

Byskov, R.K., C.B. Jacobsen, and N. Pedersen, Flow in a Centrifugal Pump Impeller at Design and Off-Design Conditions—Part II: Large Eddy Simulations. Journal of Fluids Engineering, 2003. 125(1): p. 73-83. Pierret, S. and R.A. Van den Braembussche, Turbomachinery Blade Design Using a Navier– Stokes Solver and Artificial Neural Network. Journal of Turbomachinery, 1999. 121(2): p. 326332. Zangeneh, M., A. Goto, and T. Takemura, Suppression of Secondary Flows in a Mixed-Flow Pump Impeller by Application of Three-Dimensional Inverse Design Method: Part 1—Design and Numerical Validation. Journal of Turbomachinery, 1996. 118(3): p. 536-543. Asuaje, M., et al., Numerical modelization of the flow in centrifugal pump: volute influence in velocity and pressure fields. International journal of rotating machinery, 2005. 2005(3): p. 244-255. Dawes, W.N., et al., Reducing Bottlenecks in the CAD-to-Mesh-to-Solution Cycle Time to Allow CFD to Participate in Design. Journal of Turbomachinery, 2000. 123(3): p. 552-557. Ramasamy, D., M. Samykano, and K. Kadirgama, Design Of Compressed Natural Gas Mixer Using Computational Fluid Dynamics. 2010. Majidi, K., Numerical Study of Unsteady Flow in a Centrifugal Pump. Journal of Turbomachinery, 2005. 127(2): p. 363-371. Chen, S.-L. and W.-T. Wang, Computer aided manufacturing technologies for centrifugal compressor impellers. Journal of Materials Processing Technology, 2001. 115(3): p. 284-293. Gurupranesh, P., R. Radha, and N. Karthikeyan, CFD Analysis of centrifugal pump impeller for performance enhancement. IOSR Journal of Mechanical and Civil Engineering (IOSR-JMCE) eISSN: p. 2278-1684. Goto, A., ‘Prediction of Diffuser Pump Performance Using a 3-D Viscous Stage Calculation. ASME Fluids, 1997. 97. Yedidiah, S. An alternate method for calculating the head developed by a centrifugal impeller. in ASME/JSME Fluids Engineering Conference. 1991.

12.

Langthjem MA, Olhoff N (2004). A numerical study of flow-induced noise in a twodimensional centrifugal pump. Journal of Fluids and Structures.

13.

Dawes WN, Dhanasekaran PC, Kellar WP, Savill AM (2001). Reducing bottlenecks in the CADto-Mesh-to-Solution cycle time to allow CFD to participate in design. Journal of Turbo machinery

14.

Lewis RI (1996). Turbomachinery Performance Analysis. John Wiley, New York.

15.

THE SIMULATION OF BIOGAS COMBUSTION IN A MILD BURNER “M. M. Noor1,3, Andrew P. Wandel1 and Talal Yusaf2”

16.

Lin BJ, Hung CI, Tang EJ (2002). An optimal design of axial-flow fan blades by the machining method and an artificial neural network. Proceedings of the Institution of Mechanical Engineers. Part C, Journal of Mechanical Engineering Science.

17.

Medvitz RB, Kunz RF, Boger DA, Lindau JW, Yocum AM (2002). Performance analysis of cavitating flow in centrifugal pumps using multiphase CFD. Journal of Fluids Engineering.

18.

Yedidiah S (1991). An alternate method for calculating the head developed by a centrifugal impeller. ASME/JSME Fluids Engineering Conference

19.

Oh HW, Chung MK (1999). Optimum values of design variables versus specific speed for Centrifugal pumps. Proceedings of the Institution of Mechanical Engineers. Part A, Journal of Power and Energy.

20.

Pierret S, Van den Braembussche RA (1999) Turbomachinery blade design using a NavierStokes solver and artificial neural network. Journal of Turbomachinery.

View publication stats