BASIC OF GENERATING SWIRL ACTION BY MODIFYING PISTON CROWN......AND SELECTING THE OPTIMUM DESIGN FOR PISTON CROWN FOR FABRICATING THE GROOVES

1. COMBUSTION IMPROVEMENT ON A DIRECT
INJECTION DIESEL ENGINE BY IMPLEMENTING
TANGENTIAL SWIRLING GROOVES
By:
RITESH KUMAR
(121116145)
KARTIKPALIWAL
(121116139)
Faculty advisor:-
Dr. RAJESH GUPTA

2. INTRODUCTION
The development of a fuel efficient and less polluting engine is an important aspect of today's
requirement in the area of engine research to reduce emissions and improve fuel efficiency.
TURBULENCE
FASTER
FLAME
TRAVEL
BETTER
COMBUSTION
BETTER FUEL
EFFICIENCY
This can be achieved in two ways:
• By designing the combustion chamber
• Providing the intake system so as to impart a
swirl motion to the incoming air. TURBULENCE
ROTATION
TUMBLE
SQUISH
SWIRL
Piston modification can de done to produce
• Swirl MOTION( INDUCTION /COMPRESSION SWIRL)
• SQUISH MOTION
• TUMBLE Action
Some of the concerning problems with DI Diesel engines are:
• More Brake Specific fuel Consumption & Lesser brake thermal efficiency:
• More Exhaust gases temperature:
• Longer ignition delay period:
• Pressure rise are less
• High emission rate of the oxides of Nitrogen(𝑁𝑂𝑥):

3. HOW ?

4. SWIRL SQUISH TUMBLE
1 DEFINITION
It is the rotational motion of the fluid
mass within the cylinder
It is the radial flow occurring at the end
of the Compression stroke
Squish motion generates a Secondary
flow. Rotation occurs about a
circumferential axis
2 ADVANTAGE
• Homogeneous mixture
• rapid spreading of flame front
Homogeneous mixture Homogeneous mixture
3 METHOD OF GENRATION
A) INDUCTION SWIRL
B )COMPRESSION SWIRL
Generated by the upward movement
of the piston toward TDC in
compression stroke
By the circumferential grove
provided in the center of piston
crown
4 TECHNOLOGY USED
ASFS
“ADVANCED SWIRL FLOW SYSTEM”
ATFT
“ADVANCED TUMBLE FLOW
TECHNOLOGY”
Fluid Motion in Combustion Chamber

5. WHY ONLY SWIRL ?

6. 1 FLOW IN CYLINDER
2 Mercury Marine for information obtained from Service Training Publications
Al piston technology is currently used in applications with up to 420 °C. And piston used
nowadays are generally flat crown based pistons in the trucks which lead to improper
and insufficient combustion
3 http://indian2wheels.blogspot.in/2010/10/what-do-hero-hondas-apdv-asfs-and-atft.html
Nowadays "Advanced Swirl Flow Induction System" which according to my understanding
means that the "air+fuel" mixture creates "Swirl" into the combustion chamber in the engine,
which should aid better burning of fuel
LITERATURE SURVEY AND REVIEW

7. PROJECT WORK
• From the experimental investigations and CFD analysis as done by Ballapu Harshavardhan, J.M.
Mallikarjuna on two-valve DI engine at an engine speed of 1000 rev/min., using PIV (particle image
velocimetry) and CFD with different piston shapes
• We use the case study as THE BASE OF SELECTION OF THE PISTON CROWN DESIGN FOR MAKING TANGENTIAL GROOVES
The observations and comparison parameters for different types of piston shape were categorized on
the basis of:
• Tumble ratio(TR)
• TKE
• Evaporation
• Velocity
Compared Four different design
Flat crown piston Inclined piston Flat centre bowl piston Inclined Flat bowl piston

8. A) Comparison of TR and TKE at various crank angles from CFD and PIV analysis with different piston
shapes at an engine speed of 1000 rev/min
A.Flat Head Piston B. Flat-with-central-bowl
piston
C. Inclined piston D. Inclined piston-bowl
piston
From the above we get the analysis bar chart
The bowl in the piston helps air jet to travel more
distance while accelerating, giving rise to higher kinetic
energy, higher TR would be dissipated into higher TKE.
The TR and TKE in FBP are more by about
58.3 and 21.6% respectively than those of IP.

9. B) Comparison of in-cylinder velocity vector plots with FP, FBP, IP AND IBP
• It may be because of the bowl in the piston which would
create a strong vortex motion throughout the compression
stroke .
• This strong vortex motion enhances the mixing and makes
the mixture almost uniform.
• the central bowl in piston tries to confine the vortex in it.
• Secondly greater cylinder space leads to higher angular
velocity of the vortex.
• However, increased dissipation of vortex in case of FBP as
compared To FP engine leads to higher turbulence
• Therefore, it is concluded that, in case of IBP, the mixture
distribution and range of TR are much better as compared
to those of IP.

10. C) VARIATION OF PERCENTAGE OF FUEL EVAPORATION
AT THE TIME OF IGNITION WITH VARIOUS PISTON SHAPES
The percentage of fuel evaporation is higher in case of pistons with bowl as compared to those of
pistons without bowl.
• Pistons with bowl result in higher TR and TKE. Because of higher TR and TKE, liquid fuel droplets
might be held in air rather than allowing them to go to walls, causing higher evaporation.
• Shows fuel evaporation rate from the beginning of fuel injection with various piston shapes. It is
observed that, fuel evaporation rate is more with FBP and IBP engines as compared to those of with
FP and IP engines.

11. CONCLUSION
Hence from above case study it is clear that flat bowl piston is best in all cases
Hence we select flat crown piston with centre bowl as our piston design
FLAT HEAD CENTRE BOWL PISTON
VELOCITY VECTOR
The flat-with-center-bowl piston engine gives higher in cylinder air
velocities at the end of suction stroke as compared to those of other
engines with different piston shapes considered. It gives about 12.3%
higher in-cylinder air velocity as compared to that of flat piston engine
TR & TKR
The TR and TKE with flat-with-center-bowl piston engine are higher at
the time of injection and ignition as compared to other engines with
different piston shapes considered. They are about 51.9 and 8.9% higher
at 540 CAD and 51.2 and 20.9% respectively as compared to those of flat
piston engine.
EVAPORATION RATE
Air-fuel mixing is better (i.e., ER is about one at the spark plug location)
in case of pistons with bowl as compared to pistons without bowl CFD Comparison Of flow pattern in FP
and IBP

12. WHAT WE HAVE DESINGED?
&
WHY ONLY THIS DESIGN?

13. OUR DESIGN OF FLAT WITH CENTER BOWL PISTON WITH TANGENTIAL
SWIRLING GROOVES
STEPS FOR DESIGNING THE FLAT CROWNED TANGENTIAL GROOVED PISTONS:
1 Initially piston with prescribed dimensions was designed i.e. 34cc. or 87.5mm bore.
2 Later on tangential swirling grooves were designed over top face i.e. 5.5mm, 6.5mm and 7.5mm.
3 Depth of groove is taken 2mm in each case.
4 Now the increase in cubic capacity had been observed which is paid by
Reducing the hemispherical bowl radius of the piston.
Thus the compression ratio was matched between the modified and conventional engine.

14. Experimental steps
1. Designing of the tangential groove piston
2. Importing the designed file to AVL fire and doing the in
cylinder flow simulation
3. Taking the optimum result
4. Performance, emission and combustion characteristics of
engine on AVL FIRE SUITE CFD analysis with diesel fuel and
piston with swirling groove of 2mm depth and 5.5 mm width
5. Performance, emission and combustion characteristics of
engine with the same approach and piston with swirling
groove of 2mm depth and 6.5 mm width.
6. Performance, emission and combustion characteristics of
engine with the same approach and piston with swirling
groove of 2mm depth and 7.5 mm width.

15. Conclusions
 Shapes of the head of piston has a major effect on different parameters of a DI Diesel engine. Different
shapes includes FP, FBP, BP and IBP has its effect on Tumble ratio and TKE. All the changes in head design
are mostly for attaining turbulence of flow mixture which causes better air-fuel mixing.
 A modified proposed design of tangential swirling groove on piston head having varied depth and 2mm
thickness are analyzed on AVL and it has more swirling action as compared to all other piston head design.
 This modified head design has major effects on increasing the BSFC, Brake thermal efficiency, pressure
inside chamber and outlet air temperature.
 Also proper combustion will reduce the emission of toxic gases.
 Thus this newly modified design of tangential swirling groove on piston head of a DI diesel engine has
major effect on the properties of DI engine.
Future Scope:
 Utilizing the fossil fuels in efficient manner.
 Increase in the mileage of DI Engines
 Use of highly advanced and more efficient automobiles.
 Reduction of environmental pollution caused by highly toxic gases coming out of Engines.
 Economy prospect.

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REFRENCE