2009 International Symposium on Computing, Communication, and Control (ISCCC 2009)
Proc .of CSIT vol.1 (2011) © (2011) IACSIT Press, Singapore
Experimental Investigation of Direct Air Injection Scavenged Two
Stroke Engine
M. Ayaz Afsar 1, Mr. Prafulla V. Pawar 2 Mr.Pratik Dahule3,Mr.S.Papinwar4 +
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Lecturer in Mechanical Deptt.B.N.College of Engg. Pusad(INDIA)
Final year student, Mechanical Deptt. B.N.College of Engg. Pusad(INDIA)
Abstract. In view of better utilization of payload capacity, a rapid shift towards use of 2 wheelers for
individual transportation is clearly seen in recent years & the rate of production of such 2 wheelers is sharply
rising up in our country. 2 stroke engines have the advantage of low specific weight, simplicity of operation
& less cost. However it has inherent drawbacks of poor scavenging & relatively high exhaust emissions. The
concept of making hole in transfer port by direct injection of air stream is an attractive proposition for
eliminating those drawbacks. In this paper an attempt has been made to study performance & emissions
characteristics of a single cylinder direct injection using scavenging. The variation of BSFC, NOx, Smoke &
particulate emission with brake power have been studied for both scavenging and without scavenging and
results of work shows an improvement in the performance and emissions characteristics of engine with
scavenging. This paper reports a comparative analysis of experimental investigations carried out on a single
cylinder 2 stroke S.I.Engine in carburetor with and without scavenging.
Keywords: scavenging, two stroke S.I. engine, BSFC, DAI
1. Introduction
A two stroke engine is one which complete its cycle of operation in one revolution of the crankshaft or in
two strokes of the piston. In many two stroke engines the mechanical construction is greatly simplified by
using the piston as a slide valve in conjunction with intake and exhaust ports cut in the side of the cylinder.
Two stroke engines are most simple in construction as there are very few moving parts and but more difficult
to analyze because of overlapping the inlet and exhaust. As there are only two strokes for performing four
basic operations, the overlapping processes cannot be avoided. During the downward stroke, expansion is
carried out during part of stroke and during remaining part of stroke; the exhaust and charging are carried out
simultaneously. This process is also continued during the upward motion of the piston for part of stroke, and
for remaining part of stroke, the compression is carried out. However, when applied to spark ignition engine
the two stroke cycle has certain disadvantages which have restricted its use to small engines suitable for
motor cycles, scooter, lawn movers, outboard engines, etc. In spark ignition engine the charge consists of
mixture of air and fuel. During scavenging, as both inlet and outlet ports are open simultaneously for some
time, some part of the fresh charge containing fuel escapes with exhaust. This results in high fuel
consumption or lower thermal efficiency.
2. Problem Identification
The gas exchange or scavenging process is common to all internal combustion engines. Its function is to
effect expulsion of the products of combustion from the engine cylinder and their replacement by fresh air
charge in preparation for the next working cycle. Here problem occurring is the power loss due to poor
scavenging which may rise by the short circuiting scavenging process. Also it results in reduction of fuel
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Corresponding author. Tel.: + (091- 9423654442);.
E-mail address: ( ayazafsar123 @rediffmail.com).
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efficiency. In which the fresh charge coming from the scavenge manifold directly goes out of the exhaust
ports without removing any residual gas. This is a dead loss and its occurrence must be avoided.
3. Problem Formulation
A detailed knowledge of the scavenging process becomes necessary during the development process,
when the performance and in particular the emission output of two-stroke engines needs to be qualified and
evaluated. In order to improve the performance of I.C.Engine shorcircuiting should be avoided.This is
possible only when air provide a barrier for the fresh charges to be mixed with the residual gases.In this
paper an attempt is made to regulate the natural flow of air for scavenging This paper presents an
experimental approach to describe the composition of the flow at the exhaust port by means of flow
visualization and to quantify the relative changes of the scavenging losses imposed
4. Methodology
• Modification of engine for the purpose of scavenging A drill was made in the engine for the air
passage to avoid short circuiting phenomenon in the engine.
• Development of Test-Rig i.e.design of various components such as frame, air box and dynamometer
• Performance evaluation of 2Stroke Engine without Direct air injection and calculation of the various
engine parameters such as brake power, brake specific fuel consumption, brake thermal efficiency
• Performance evaluation of 2Stroke Engine with Direct air injection and calculation of the various
engine parameters such as brake power, brake specific fuel consumption, brake thermal efficiency
5. Experimental Setup
The experimental setup for performance evaluation of direct air injection scavenged engine is as shown
in fig1.
Fig.1. Experimental Setup
1-Engine Frame, 2-Crank Case, 3-Caburettor, 4-Air Box, 5-Fuel Tank, 6-Burrete, 7-Exhaust Of Engine,
8-Puc Machine Setup, 9-Rope Brake Dynamometer, 10-Air Box Stand, 11-Machine Stand, 12-Hole Provided
For Direct Air Injection, 13-Tachometer
6. Observation
•
•
•
•
•
•
Diameter of orifice = 32mm
Swept volume = 150cc
Cv of fuel = 42500kj/kg
Specific gravity of fuel = 0.8
Cp of water = 4.1868kj/kgk
Diameter of brake drum = 30cm
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• Speed of engine = 1500 rpm
• Room temp = 302k
Table 1. Comparative Performance Evaluation Of Various Parameters On Varing Load
Sr.
No.
1
2
3
4
Load
Load
(Kg)
00
0.5
1
1.5
Speed
(RPM)
Without
DAI
115
110
106
102
Mass Of Fuel
(Kg/Sec)
Without With
DAI
DAI
BSFC
(Kg/KWhr)
Without With
DAI
DAI
Thermal
Efficiency
With
DAI
Brake Power
(Watt)
Without With
DAI
DAI
Without
DAI
With
DAI
170
160
151
154
00
8.48
16.3
23.6
9.34
8.77
8.69
8.62
00
0.037
0.019
0.013
00
2.25
4.37
6.36
00
3.304
6.27
9.69
00
12.3
23.3
35.6
9.17
8.67
8.62
8.54
00
0.025
0.013
0.009
Table 2.Exhaust Emmisions
Sr. No.
Emmisions
1
2
CO (% by Vol)
HC (ppm)
Without DAI
Scavenging
1.43
1840
With DAI Scavenging
1.21
1156
7. Result
The performance of the engine and the combustion parameters of engine by using petrol as a fuel are
represented as below.
7.1. Combustion Parameter
There is increase in BP of the engine because of injection of outside air in to the cylinder.
7.2. Exhaust Emission
The emissions of hydrocarbons are decreased by almost 38% where as carbon monoxide emission
decrease by 18%.
This shows that the modified engine can be more esuriently.
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8. Conclusion
The significant conclusion from the present experimetal investigation are summarized as follows:• The engine can be successful operated with the modified engine having a direct air injection upto the
maximum speed of 5500 rpm.
• Improvement in BSFC and more complete combustion of the modified engine were observed as
compares to the conventional engine.
• The CO and UBHC emissions levels were less than conventional engine. The CO emissions were
reduced by 18% at rated power output & UBHC emissions were reduced by 38% at rated power
output.
9. Acknowledgement
We are thankful to the Principal, Prof.N.M.Gatphane, for providing all the facilities. We are indeed thankful to
Prof.A.M.Wankhade, H.O.D. of Mechanical Engg. Department for his time to time suggestions and other faculty
members who gave necessary help as required.
10. References
[1]
Bryan Willson, Justin Mick and Stephanie Mick. “Development of an Externally-Scavenged Direct-Injected
Two- Stroke Cycle Engine”, Colorado State University, SAE International, International Off- Highway &
Powerplant
Congress & Exposition Milwaukee,. September 11-13, 2000 Wisconsin.
[2] CUDINAM.( 2004) “Model testing the two-phase scavenging system in a two-stroke petrol engine”, Proceedings
of the Institution of Mechanical Engineers. Part D, Journal of automobile engineering, vol. 218.
[3] David Shawcross, Colin Pumphrey and David Arnall.( March 6–9, 2000) “A Five-Million Kilometer, 100-Vehicle
Fleet Trial, of an Air-Assist Direct Fuel Injected, Automotive 2-Stroke Engine”, Orbital Engine Co. Pt. Ltd., SAE
2000 World Congress Detroit, Michigan.
[4] Miles, P. C.; Green, R. M.; Witze, P. O. (11-14 Jul. 1994) “Comparison of in-cylinder scavenging flows in a twostroke cycle engine under motored and fired conditions.” Presented at the 7th International Symposium on
Applications of Laser Techniques to Fluid Mechanics, Lisbon, Portugal.
[5] Dr. Mathur M.K., Sharma, “Testing and Performance”, Textbook of Internal Combustion Engine, Seventh Edition,
Dhanpat Rai & Co Ltd, p.p.556-575.
[6] Dr. V Ganesan, “Performance Parameters and Characteristics”, Textbook of Internal Combustion Engine, Third
Edition, Tata McGraw-Hill Publishing Co Ltd, p.p.386-534.
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