exhaust manifold design

7/25/2019 Exhaust manifold design

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DESIGN & ANALYSIS OF INDIVIDUAL EXHAUST SYSTEM

IMPROVING TRANSIENT RESPONSE OF

A TURBO DIESEL ENGINE

BY

ISHAN DEV

PARIKSHIT BAJPAI

PUSHKAR SHUKLA

SANDEEP KR. MISHRA

JSS MAHAVIDYAPEETHA

JSS ACADEMY OF TECHNICAL EDUCATION, NOIDA

DEPARTMENT OF MECHANICAL ENGINEERING

2014-2015


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Introduction

Turbo-diesel refers to any diesel engine equipped with a turbocharger

Turbo-diesels in auto!obiles offer a higher refine!ent le"els than their naturcounterparts

In power boosting of engines# the application of con"entional turbochargers could

li!ited i!pro"e!ent because it is effecti"e in a narrow flow range

%ne of the !ain handicaps of turbocharged diesel engines is their low dyna!ic re

low speed range# co!pared with spar& ignition ones


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%b'ecti"e and (olution %ptions

I!pro"ing the dyna!ic perfor!ance of turbocharged diesel engine# by energy sa"ing

in the turbocharger acceleration by engine perfor!ance !odelling during transient

operation with indi"idual e)haust configurationThe possible solutions *

(upple!ent the usual e)haust-dri"en turbo with another turbo dri"en by an

electric !otor

+sing "ariable-no$$le or twin-scroll turbochargers

+sing a turbocharger spool "al"e to increase e)haust gas flow speed to the

turbine

,. Inta&e .)haust /anifold e!odeling

%ur (olution * e!odeling the e)isting e)haust syste! as an indi"idual e)haust

!anifold in collector configuration


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The Theory of Turbocharging

Basically# the power output of an engine depends on the a!ount of energy# in the

fuel# with which its cylinders can be charged

In a naturally aspirated engine# at!ospheric pressure forces the air in The press

air ulti!ately in the cylinder is lower than at!ospheric (o also# therefore is its de

onsequently# any !easure such as supercharging# turbocharging or cooling the

increase its density !ust be the &ey to increasing power output per unit of si$e an

of the engine


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The Theory of Turbocharging

, turbocharger is a co!pressor dri"en by a turbine powered by e)haust gas ewhich would otherwise be wasted

This !ethod of forced induction is so!eti!es referred to as ressure harging

Turbochargers are effecti"e o"er a relati"ely narrow speed range# and therefore h

be carefully !atched to the engine


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Types of Turbocharging

There are two basic approaches

onstant ressure Turbocharging

ulse Turbocharging

ulse turbocharging# despite the fact that turbine efficiency is reduced by pulsat

"irtually uni"ersal for auto!oti"e applications


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onstant ressure Turbocharging

.ntails discharging the e)haust gas into a large !anifold# in effect a plen

substantially the !agnitude of the pulsations before it is deli"ered to the turbine

The efficiency of energy con"ersion within the turbine in this way is significan

that of pulse turbocharging

The penalty is a loss of !uch of the &inetic energy of the gas as it lea"es the e)hau

+nless the large !anifold is ther!ally insulated# the heat losses fro! it !ay be co


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ulse Turbocharging

The principal disad"antage of pulse turbocharging is that# because the flow int

pulsating# with alternating periods of $ero flow fro! indi"idual cylinders# i

inherently lower

In !ulti-cylinder engines# howe"er# this disad"antage can be largely ob"iated

e)haust !anifold design

It can be offset by the a"ailability of a high proportion of &inetic# in addition

energy# for con"ersion into wor& in the turbine

To ta&e !a)i!u! ad"antage of the pulse energy# the turbocharger should be spossible to the engine e)haust ports# so that the "olu!es of the passages fro! th

the turbocharger are s!all

This helps to ensure rapid response in transient conditions


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ulse Turbocharging

Front Upp

Front Low

ulse effect for a single-cylinder engine with a short pipe between

the e)haust "al"e and the turbine

,s the e)haust "al"e crac&s open# at ,# the pressure drop acrossit is abo"e the critical "alue so no pressure rise is apparent up to

B because all the energy due to e)pansion is lost in turbulent

!i)ing

Between B and # the pressure rises increasingly steeply#

though has no effect on turbine speed

The !ain rise# between and 3# occurs because the flow of gasinto the pipe is greater than that escaping through the turbine

ro! 3 to .# the pressure falls down to at!ospheric as all the

e)hausted gas is discharged through the turbine


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, disad"antage of turbocharging is what is ter!ed turbocharger lag

This arises because of the need# as the de!and of torque fluctuates# to ac

decelerate the rotor to and fro! e)tre!ely high speeds

or a diesel engine# turbocharged "ersions require a supply of e)tra air as wel

producing the e)tra power

onsequently# the fuel supply has to be increased progressi"ely with the air supplbeing in'ected al!ost instantaneously with pedal angle change

The roble! * Turbocharger ag


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The (olution * .)haust /anifold e!odelling

+sing a ollector onfiguration Indi"idual .)haust (yste! instead of the og.)haust

educes Turbulence and .nergy osses in the e)haust !anifold

/ini!u! !odification required in the e)isting setup of turbocharged diesel en

o require!ent of additional parts and !odification in other co!ponents of th

.asy pac&aging and low cost co!pared to other options


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og (tyle /anifold * .ach e)haust port in the cylinder head discharges its e)ha

long single tube running the length of the !anifold

ollector (tyle /anifold * &eeps each cylinder6s e)haust pulse separate until t

single point called a 7collector8

9hile co!pactness and econo!ical !anufacturing are ad"antages to the log design# there are !ultiple perfor!ance disad"antages

The Turbo /anifolds * og and ollector Types


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og (tyle /anifold

In a og style e)haust# at each !erge point# the"elocity of the indi"idual e)haust pulse as it

tra"els toward the turbine is disrupted by the

inco!ing e)haust pulse fro! another cylinder

The energy found in the secondary path of the

!anifold is !ade up of the energy co!bined

fro! the pulses tra"eling down each of thepri!ary paths

In a log design# energy is lost at point , due to

the turbulence created fro! the two pulses

!erging

.)haust low aths o

/anifold


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ollector (tyle /anifold

%n a collector style !anifold# the e)haust

pulse fro! each cylinder tra"els fro! the

cylinder head# down each !anifold pri!ary

tube# and to the !anifold collector The

pulses then !erge and tra"el down the

!anifold secondary tube to the turbine side

of the turbo

The basic idea behind &eeping each e)haust

pulse separate to the collector is to controland !ini!i$e the turbulence created when

the e)haust pulses !erge

9ith a design that creates turbulence inside

the !anifold# energy is wasted# creating

heat instead of spinning the turbine

.)haust low aths of a ol

/anifold


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ollector :s og (tyle /anifolds

In a collector !anifold style# turbulence is li!ited to one point instead of two# !

energy potential to the turbo

This results in faster turbo spool up# and potentially !ore energy to create boost

the fuel in'ection co!puter

;owe"er# reducing turbulence also has another desirable effect< the creation of

e)haust path for the engine

, less turbulent e)haust path !eans less wor& the engine has to do to 7e)pel8 the

fro! the co!bustion cha!ber# which results in !ore energy going to the creation


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.)haust /anifold 3esign onsiderations

unner :olu!e * 9hile a larger runner dia!eter does facilitate lower e)haust bacfor better flow on the top-end# it does cause a lower e)haust "elocity , lowe

"elocity will cause longer spool ti!es# and less transient response out of the turbo

unner ength * .qual length runners will !a&e sure that the e)haust pulses will

out e"enly and arri"ing at the turbine wheel on the turbo at there own ti!e in

order , longer runner !anifold will ha"e better flow up top# while a shorter !ayield a faster spool# with also less transient lag


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.)haust /anifold 3esign onsiderations

(urface ,rea - ,s e)haust gas heat energy is lost# the gasses slow down anconsequently hit the turbine hit less force =eeping the surface area of the !anifo

to a !ini!u! will &eep heat loss to a !ini!u!

ollector ,ngle * The collector angle is i!portant in dialling in how the e)hau

gasses will co!e together and !erge before the turbo The less the angle the bett

the flow# but often ti!es the space you ha"e to wor& with will dictate the collectdesign


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.)haust /anifold 3esign

Inside 3ia!eter

ri!ary ipe 3ia!eter

cc > ylinder :olu!e in cc

> ri!ary ength

(econdary ipe 3ia!eter

I3 > ri!ary ipe 3ia!eter

Tailpipe Internal 3ia!eter

cc > ylinder :olu!e in cc

> ri!ary ength


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.)haust /anifold 3esign

ri!ary ipe ength

/ > The engine speed to which the e)haust is being tuned

.3 > 1?0@ plus the nu!ber of degrees the e)haust "al"e opens before B3

> ri!ary pipe length Aon a 4-1 !anifold# or ri!ary pipe length plus (

pipe length Aon a 4-2-1 !anifold

ollector ength

> 3ia!eter of ollector Inlet

> 3ia!eter of ollector %utlet

C > ,ngle of ollector Taper AD@ to ?@

Total ength of ollector and Tailpipe

> ri!ary ipe ength


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(toc& .)haust /anifold


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/odelled .)haust /anifold

Fig: Collector Type Exhaust Manifold

Fig: Isometric Vie


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low ,nalysis of the !odelled e)haust !anifold

Number of cells in X 26Number of cells in Y 12Number of cells in Z 12

Total cells 47599Fluid cells 14920

Solid cells 16050Partial cells 16629Irreular cells 0Trimmed cells 0

alculation /esh Basic /esh 3i!ensions

u!ber %f ells


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R'()*'Flow Analysis: Velocity Variation of a collector style


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Flow Analysis: Velocity Variation of a log style


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Flow Analysis: ress!re Variation of a collector style


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,ni!ation


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Flow Analysis: ress!re Variation of a log style

Flow Analysis: "emperat!re Variation of a collector style


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lt (


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Name !inimum !a"imumPressure #Pa$ #1#$2%21 2451$0%&&Tem%erature #&$ &$$%44 996%2$

'ensit( #)*m+,$ 0%2# 0%-elocit( #m*s$ 0 6$2%&24-elocit( .X/ #m*s$ '$05%4&5 2&2%0#5-elocit( .Y/ #m*s$ '6$2%4$6 11&%#46-elocit( .Z/ #m*s$ '1&0%61$ $##%$1#Tem%erature .Fluid/

#&$

&$$%44 996%2$

-orticit( #0*s$ 21%$04 1$6#&5%1&S1ear Stress #Pa$ 0 &50%44elati3e Pressure#Pa$

'29592%#9 14$&05%&&

eat Transferoecient #*m+2*&$

0 0

Surface eat Flu" 0 0

esults (u!!ary


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eferences

Earett T=# ewton = and (teeds 9# The /otor :ehicle# Butterworth ;eine!ann# on ;eisler# ;ein$# ,d"anced .ngine Technology# (,.# Ereat Britain# 1FF5 ;eywood# Gohn B# Internal o!bustion .ngine unda!entals# /cEraw-;ill# Inc ew Y /orrison# Gohn and (!ith# hilip ;# (cientific 3esign of .)haust and Inta&e (yst

/,# obert Bentley ublishers# 1FD2 9ren# and % Gohnson# 7Eas 3yna!ics (i!ulation for the 3esign of Inta&e and .)

atest Techniques8 (,. aper o F51HDT E Blair# 3 /ac&ey# / ,she# and E hatfield 7.)haust Tuning on a ou

.)peri!entation and (i!ulation8 (,. aper o 2001 01 1DFDK421? G i# Lhou# 3 Giang# and = an 7requency ,nalysis Technique for Inta&e and .

3esign8 (,. aper o F520D0 /atus# 7/odeling of .)haust (yste!s with 38 (,. aper o F410?2 icardo (oftware 9a"e :51 Basic /anual Burr idge# Illinois# +(, A200H icardo (oftware 9a"e :51 .ngine /anual Burr idge# Illinois# +(, A200H

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