analysis of engine cooling waterpump of car & significance of its

International Journal of Mechanical Engineering and Technology (IJMET), ISSN 0976 –

6340(Print), ISSN 0976 – 6359(Online) Volume 4, Issue 3, May - June (2013) © IAEME

100

ANALYSIS OF ENGINE COOLING WATERPUMP OF CAR &

SIGNIFICANCE OF ITS GEOMETRY

Bhavik M.Patel1, Ashish J. Modi

2, Prof. (Dr.) Pravin P. Rathod

3

1(PG Student, Mechanical Engineering Department, Government Engineering College, Bhuj)

2(Assistant Professor, Mechanical Engineering Department, Government Engineering

College, Bhuj) 3(Associate Professor, Mechanical Engineering Department, Government Engineering

College, Bhuj)

ABSTRACT

To study behaviour of flow in cooling water pumps, we done extensive search and

gone through numerous research paper and blogs.We found that many researchers carried out

their analysis on other cooling system components like radiator, cooling water jacket and

fans. But it is very difficult to find researchers worked on cooling water pumps. However

cooling system consists of centrifugal pump which is widely used in other industry. After

reviewing all research paper on centrifugal pumps we found that most of the problems are

related to cavitationand low efficiency.Some researchers give importance to improvement of

blade angle and blade design to reduce cavitation effect while some researches concentrates

on efficiency of the pump irrespective of cavitation effect mostly in the industry where

cavitation effect is negligible. After analyzing some old water pumps of various vehicles we

found that major problem that pump is facing is due to cavitation effect on blades at High

RPM. This research is aimed to analyze the role of centrifugal water pump in automobile

engine cooling system and to obtain relation between pump geometry and pump flow

characteristics.

Keywords: Water pump, Engine cooling system, simulation, CFD, ANSYS, Cooling water

pump Geometry, cavitation, coolant flow, flow characteristics

INTERNATIONAL JOURNAL OF MECHANICAL ENGINEERING

AND TECHNOLOGY (IJMET)

ISSN 0976 – 6340 (Print)

ISSN 0976 – 6359 (Online)

Volume 4, Issue 3, May - June (2013), pp. 100-107

© IAEME: www.iaeme.com/ijmet.asp Journal Impact Factor (2013): 5.7731 (Calculated by GISI) www.jifactor.com

IJMET

© I A E M E



101

INTRODUCTION

Automobile Cooling pump is the key part of the Automobile cooling system that keep

circulate the coolant throughout it and takes away excess heat from engine at different Engine

rpm and torque conditions. Also it's surrounding atmospheric conditions can vary coolant

characteristics. This research involves the investigations on the existing coolant pump of car

(Maruti SUZUKI Alto), to understand the flow characteristics. The research is carried out in

three approaches to understand the behavior of fluid. The first one is "Theoretical approach"

in which Empirical relations are used. It describes how the desired pump operating

parameters such as flow rate, specific speed of pump etc. can be derived. It also describes the

coolant characteristics & understanding of flow characteristics in the closed, pressurized

automobile cooling system. The another one is "Practical approach" in which flow rate and

fluid pressure of pump flow are measured on existing coolant pump of Maruti SUZUKI Alto

at different engine rpm. The third approach involvesthe “Computational Fluid Dynamics" of

pump flow, which itself provides graphical representation of the relations between flow

characteristics and pump geometry. The "Result discussion" section provides brief discussion

on the results which are derived after these three approaches.

THEORITICAL APPROACH

Below steps has been carried out to obtain desired coolant flow rate.

• Obtained heat rejection data for specific engine model and rating. This information is

available from the engine technical data sheet. Maximum heat rejection (nominal +

tolerance) values are used.

• Obtained density and specific heat values for coolant. Table 1 provides these values

for the specific coolant.

• Using these values in Empirical equations we can calculate coolant flow rate as

below.

Heat Rejection by Engine Calculation

Before a coolant flow rate can be calculated, we must calculate how much heat is

being rejected through the engine. The heat input to the engine equals the sum of the heat and

work outputs. From following equation, heat input values are derived with the use of Power -

Torque - Speed curve. As per SAE papers, the total heat output of engine is the sum of total

exhaust heat, heat loss to the surroundings, total heat dissipated by engine coolant and total

heat dissipated by engine oil. It is also assumed that approximately one third of total heat

output is equal to the total heat dissipated by the engine coolant. The total heat input can be

calculated as follows:

Heat input to engine�KW� �Brake Power�BP� � 100

Thermal Ef�iciency�%�

International Journal of Mechanical Engineering and Technology (IJMET), ISSN 0976

6340(Print), ISSN 0976 – 6359(Online) Volume 4, Issue 3, May

Coolant Flow Calculation

The coolant flow required for different heat load from the engine

can be calculated using the following equation:

Power - Engine RPM - Torque Curve

SAE 2001 paper states that conventional coolant flow rate on smaller engines with

mechanically driven water pumps vary between 2.0 to 2.6 L/min/Kw. The flow rate derived

from the above equation falls under this criteria.

curve based on above equations.

Specific Speed Specific speed is a number characterizing the type of impeller in a unique and coherent

manner. Specific speed are determined independent of pum

comparing different pump designs. The specific speed identifies the geometrically similarity

of pumps.

Typical values for specific speed

• radial flow - 500 < Ns< 4000

vanes - double and single suction. Francis vane impellers in the upper range

• mixed flow - 2000 < Ns< 8000

pumps

• axial flow - 7000 < Ns< 20000

By calculation, the specific speed value falls between 1000

condition. So it suggestsusing radial vane impeller pump and the

cars also proves true that the car coolant pumps are centrifugal pumps with radial


6359(Online) Volume 4, Issue 3, May - June (2013) © IAEME

102

The coolant flow required for different heat load from the engine components to the radiators

can be calculated using the following equation:

Torque CurveRequired Pump RPM - Pump Flow Rate Curve



under this criteria. Graph 1 represents Pump rpm v/s flow rate

Specific speed is a number characterizing the type of impeller in a unique and coherent

manner. Specific speed are determined independent of pump size and can be useful


Typical values for specific speed - Ns - for different designs in US units (US gpm, ft)

< 4000 - typical for centrifugal impeller pumps with radial

double and single suction. Francis vane impellers in the upper range

< 8000 - more typical for mixed impeller single suction

< 20000 - typical for propellers and axial fans

peed value falls between 1000-2000 under different operating

radial vane impeller pump and the actual pump used in existing

car coolant pumps are centrifugal pumps with radial

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0 2000

Pu

mp

Flo

w R

ate

(Kg

/s)

Pump RPM


June (2013) © IAEME

components to the radiators

Pump Flow Rate Curve



Pump rpm v/s flow rate

Specific speed is a number characterizing the type of impeller in a unique and coherent

p size and can be useful


(US gpm, ft)

typical for centrifugal impeller pumps with radial

double and single suction. Francis vane impellers in the upper range

more typical for mixed impeller single suction

under different operating

actual pump used in existing

car coolant pumps are centrifugal pumps with radial vanes.

2000 4000

Pump RPM



103

Typical Coolant Characteristics

The engine’s cooling system is designed to meet specific guidelines. The proper

coolant/antifreeze will provide the following functions:

• Adequate heat transfer

• Compatibility with the cooling system’s components such as hoses, seals, and piping

• Protection from water pump cavitation

• Protection from other cavitation erosion

• Protection from freezing and from boiling

• Protection from the build-up ofcorrosion, sludge, and scale

Following graph represents the Engine coolant saturation pressure at different fluid

temperature. Though cavitation is the phenomenon of "constant temperature boiling due to

low pressure" that is due to sudden increase in the fluid velocity at pump inlet when impeller

suck the fluid so there is sudden pressure drop of fluid. Table 1 show the coolant properties

when the fluid temperature is 80 deg. C.

Engine Coolant Saturation Pressure in psi Table 1

Pump Flow Characteristics

Pump inlet pressure is higher compare to saturation pressure at different temperature to

reduce cavitation effect at inlet side.

The cooling system and its components must meet both criteria.

A) Maximum pressure design limits. At any point in the cooling system that exceed the

maximum pressure for the local components such as radiators etc. and

B) The minimum pressure at any location in the cooling system shall not fall below the vapor

pressure of the coolant to prevent low pressure boiling. A minimum pressure/head is also

required at the pump inlet to avoid cavitation, minimize metal erosion and noise.

Coolant Property Value with

UNIT

Molar Mass 0.07343 Kg/mol

Density 1.03 Kg/m^3

Specific Heat 3579.71 J/Kg*K

Thermal

Conductivity

0.4153 W/m*K

Dynamic Viscosity 2.8 Centipoise

0

5

10

15

0 20 40 60 80 100 120

Satu

rati

on

Pre

ssu

re (

psi

)

Temp in deg. C



104

PRACTICAL APPROACH

After determining the required coolant flow rate, pump performance establishes the

maximum allowable external resistance. Piping and heat transfer equipment resist water flow,

causing an external pressure head which opposes the engine driven pump. The water flow is

reduced as the external pressure is increases. The total system resistance must be minimized

in order to ensure adequate flow. A cooling system with excessive external pressure heads

will require pumps with additional pressure capacity. With Practical approach, the pressure

drop in the fluid flow can be measured by totaling the pressure drop in each of the system's

components.

CFD ANALYSIS OF ENGINE COOLING WATER PUMP

Define Goals From theoretical and practical approach, pump design parameter are obtained which affects

the pump flow characteristic. To study pump flow characteristic, Ansys CFX is used which

will provide results with graphical representation of flow characteristic like pressure,

velocity, mass flow rate etc. at different location of pump.

Flow Geometry and Mesh Creation The pump model geometry is complex and asymmetric due to the blade and volute shape.

The 3D CAD software was usedto extractpump fluid profile geometry from pump modelThe

pump model specification is given bellow in table 3. An Optimized mesh is used for analysis.

The model is divided into twodomains i.e. rotating and stationary.



Mesh - Stationary and

Identify Domain and Boundary Condition

In steady state type analysis,

& Stationary. The rotating domain includes the fluid profile which

impeller while the rest of the fluid region is defined as

defined for the fluid flow at impeller inlet, impeller outlet, Inlet and outlet of pump with

General connection and conservat

mixture of Ethylene Glycol & water is defined with required properties for the solver

equation in material library. The ma

investigated for cavitation effect in pump

Impeller Specification

Hub Dia 19.35 mm

Impeller Outside Dia 56 mm

Suction Dia Impeller OD

Flow Type Radial Flow

Blade Type Circular 2D

No of Blade 7 (CCW)

Total Height 23.47 mm



105

Pump Geometry 1

tationary and Rotating domain of pump flow

Boundary Condition

In steady state type analysis, Non Buoyant, two fluid domains are defined

rotating domain includes the fluid profile which is in contact with the

est of the fluid region is defined as Stationary domain. Interfaces are


General connection and conservative interface flux in fluid flow.Engine coolant, a 50/50 %


The mass transfer model is set to cavitation and the results are

effect in pump at different pump rpm.

19.35 mm

56 mm

Impeller OD

Radial Flow

Circular 2D

7 (CCW)

23.47 mm



two fluid domains are defined - Rotating

in contact with the

Stationary domain. Interfaces are


Engine coolant, a 50/50 %


and the results are



RESULT

Above results shows contour plots of velocity and pressure on different planes. Below graph

shows flow rate vs. head at different engine RPM. By carefully studying each case, it can be

concluded that at very low RPM, flow is turbulent. Also

cavitation is achieved at medium engine speed.

SIGNIFICANCE OF PUMP GEOMETRY

A common misconception about cooling systems is that if the coolant flows too

quickly through the system, it will not have time to cool properly.

cooling systems are a closed loop, coolant allowed to stay in the radiator longer will also

stay in the engine block longer producing increased coolant temperatures. This can easily lead to ‘hot spots’ and ultimately, engine failure.

increases velocity by reducing pressure with providing sudden reduction in cross se

at outlet of pump. Sudden reduction also result into turbulent flow at the outlet which

contradictory helps in maintaining engine block temperatures which we can

above results also.

However turbulent flow at inlet leads to less pump

below vapor pressure of coolant then it leads to pump cavitation. From above results we can

conclude that venturi effect at the inlet of the pump helps in avoiding cavitation by increasing

inlet fluid pressure above vapor pressure at normal speed



106

0

2

4

6

8

0 20 40

HE

AD

(ft

)

FLOW RATE (GPM)

3000 RPM 2625 RPM



concluded that at very low RPM, flow is turbulent. Also best pump efficiency with less

cavitation is achieved at medium engine speed.

GEOMETRY


quickly through the system, it will not have time to cool properly. Because automotive


stay in the engine block longer producing increased coolant temperatures. This can easily lead to ‘hot spots’ and ultimately, engine failure. To avoidthesecentrifugal pump

velocity by reducing pressure with providing sudden reduction in cross se


contradictory helps in maintaining engine block temperatures which we can

However turbulent flow at inlet leads to less pump efficiency and also if pressure falls

low vapor pressure of coolant then it leads to pump cavitation. From above results we can

effect at the inlet of the pump helps in avoiding cavitation by increasing

apor pressure at normal speed and decreasing velocity of fluid.



60

FLOW RATE (GPM)

2250 RPM



best pump efficiency with less


Because automotive


stay in the engine block longer producing increased coolant temperatures. This can centrifugal pump

velocity by reducing pressure with providing sudden reduction in cross section area


contradictory helps in maintaining engine block temperatures which we can see through

efficiency and also if pressure falls

low vapor pressure of coolant then it leads to pump cavitation. From above results we can

effect at the inlet of the pump helps in avoiding cavitation by increasing

and decreasing velocity of fluid.



107

CONCLUSION

The summary of the present research paper as follows

1. By studying different design points carefully it can be concluded that the existing

pump of Alto car is designed for best performance at normal car speed. Pump

geometry at inlet (venturi effect) avoids cavitation phenomenon and increase pump

efficiency significantly.

2. However at low and high speed of car, pump is subject to more cavitation. So there is

scope to improve that.

3. Sudden reduction at pump outlet is observed in existing pump, which is generally to

be avoided while designing the pump. But it helps in avoiding hot zones by increasing

velocity and making flow turbulent.

REFERENCES

[1] Rodrigo Lima Kagami, Edson LuizZaparoli, Cláudia Regina de Andrad, “ Cfd Analysis

of An Automotive Centrifugal Pump”, 14th Brazilian Congress of Thermal Sciences

and Engineering, October18-22, 2012

[2] Munish Gupta, Satish Kumar, Ayush Kumar, “Numerical Study of Pressure and

Velocity Distribution Analysis of Centrifugal Pump”, International Journal of Thermal

Technologies, ISSN 2277 – 4114,Vol.1, No.1 (Dec. 2011) ,pp-118-121.

[3] R.Ragoth Singh, M.Nataraj “Parametric Study and Optimization of Centrifugal Pump

Impeller by Varying The Design Parameter Using Computational Fluid Dynamics: Part

I”, Journal of Mechanical and Production Engineering (JMPE) ISSN 2278-3512 Vol.2,

Issue 2, Sep 2012 ,pp-87-97

[4] E.C. Bacharoudis, A.E. Filios, M.D. Mentzos1 and D.P. Margaris,“Parametric Study of

a Centrifugal Pump Impeller by Varying the Outlet Blade Angle”, The Open

Mechanical Engineering Journal, 2008, 2, pp-75-83

[5] Mohammed Khudhair Abbas “Cavitation In Centrifugal Pumps”, Diyala Journal of

Engineering Sciences, ISSN 1999-8716, 22-23 December. 2010, pp. 170-180

[6] AbdulkadirAman, SileshiKore and Edessa Dribssa ,“Flow Simulation and Performance

Prediction of Centrifugal Pumps Using CFD-Tool”, Journal of EEA, Vol. 28, 2011,

pp-59-65.

[7] Weidong Zhou, Zhimei Zhao, T. S. Lee, and S. H.Winoto ,“Investigation of Flow

Through Centrifugal Pump Impellers Using Computational Fluid Dynamics”,

International Journal of Rotating Machinery, 9(1): 49–61, 2003,pp-49-61.

[8] S.Rajendran and Dr.K.Purushothaman,“Analysis of a Centrifugal Pump Impeller Using

ANSYS-CFX”, International Journal of Engineering Research & Technology (IJERT)

Vol. 1 Issue 3, May – 2012,ISSN: 2278-0181,pp-1-6.

[9] http://www.engineeringtoolbox.com/specific-speed-pump-fan-d_637.html

[10] Manish Dadhich, Dharmendra Hariyani and Tarun Singh, “Flow Simulation (Cfd) &

Fatigue Analysis (Fea) of a Centrifugal Pump”, International Journal of Mechanical

Engineering & Technology (IJMET), Volume 3, Issue 3, 2012, pp. 67 - 83, ISSN Print:

0976 – 6340, ISSN Online: 0976 – 6359.

[11] Kapil Chopra, Dinesh Jain, Tushar Chandana and Anil Sharma, “Evaluation of Existing

Cooling Systems for Reducing Cooling Power Consumption”, International Journal of

Mechanical Engineering & Technology (IJMET), Volume 3, Issue 2, 2012,

pp. 210 - 216, ISSN Print: 0976 – 6340, ISSN Online: 0976 – 6359.

analysis of engine cooling waterpump of car & significance of its

Documents

cooling water pump geometry

pump flow characteristics

cooling water pumps

cooling water jacket

desired pump

cooling system components

coolant flow

role of centrifugal