In this paper, the consequence of a distorted tape and a shrouded valve on the swirl features of a individual cylinder, air cooled engine were investigated. A steady flow analysis of swirl sweetening techniques was conducted on a steady flow bench with a whirl adapter to obtain a planetary position of the consumption flow. The fluctuations of assorted non-dimensional parametric quantities such as Coefficient of Discharge, Flow Coefficient, Swirl Coefficient and Swirl Ratio for different valve lifts were studied. A higher whirl ratio and swirl coefficient was obtained with the diesel caput inserted with a shroud and distorted tape.
In-cylinder fluid gesture has been investigated since the beginning of engine development. In the hundred old ages of development, the automotive industry has made important promotion in burn rate sweetening through caput and port optimisation, flicker location and valve timing. Before the coming of complex computational simulation, applied scientists created methods to rush up the development of new, advanced engine designs from those of high public presentation designs through similarity and parametric surveies. This method, most normally used by the Diesel industry, provided a first order appraisal of a new design. The little engine community, due to other restraints, has non kept gait with the developments of the automotive industry, but certain techniques can be adapted to little engine development. Through a greater apprehension of in cylinder fluid flow and techniques developed in the automotive industry, the little engine community can by-pass uneffective engineering to run into the burn rate and emanation demands of tomorrow. By optimising burning with enhanced in-cylinder flow gestures and by agencies of charge stratification achieved through gasolene direct injection technique, the thin operating burning bound can be significantly extended and the emanations of pollutants can be reduced [ 1 ] . The in-cylinder flow is a decisive factor for burning in the engine, which in bend provides important effects on the engine public presentation. In-cylinder fluid flows govern the fire extension rate in the flicker ignition ( SI ) engines and command the air-fuel commixture in the Diesel engines [ 2 ] . In IC engines, initiation of air is of greater importance than that of fuel even though air and fuel are critical substances in the burning. In an IC engine, the air enters the burning chamber through the consumption port with high speed during the intake shot. Therefore high kinetic energy of the fluid flow during intake shot, subsequently consequences inn high turbulency. Therefore, a good apprehension of the development procedure of fluid gesture in internal burning engines is critical to develop engine designs with the most attractive operating and emanation features [ 3 ] .
The steady flow experimentation of this probe was conducted on a flow bench outfitted with a whirl arranger to mensurate the frequence of the flow of the caput and swirl adapter fond regard. A swirl trial rig similar to [ 4 ] was made except that a vane method was used for mensurating the whirl alternatively of an impulse whirl metre. An Acrylic tubing of outer diameter 99.1cm, interior diameter 92cm and length 1ft was selected as the cylinder for the Diesel engine. This crystalline stuff was selected since visual image of flow and the rotary motion of the paddle wheel inside the cylinder is necessary. An Aluminium block of 35mm thickness and 15x15cm was used as an intermediate to fix the acrylic tubing to the engine cylinder.
The whole apparatus was supported on a base along with an air box on the top which was connected to the intake side of the blower. An orifice home base was fixed to the inlet side of the air box to mensurate the mass flow rate. A blower of 16000 revolutions per minute, 600W, and 3.3m3/min discharge rate is used to invest air through the consumption valve in order to imitate the existent engine runing status A Bosch air flow metre was placed in between the blower and the air box to mensurate the mass flow rate of the air inducted into the blower. Similarly, the blower was clamped to the intake side of the cylinder caput with a flow straightener in between to guarantee laminar flow to the engine caput
To mensurate the force per unit area bead in the engine a Manifold Absolute Pressure ( MAP ) detector was besides used. The rotary motion of the paddle wheel gives a step the whirl inside the cylinder. The paddle wheel used for the apparatus was developed utilizing Rapid prototyping technique. A mechanism for traveling the paddle wheel within the engine cylinder volume was besides manufactured in order to analyze whirl at different places in the cylinder.
The engine valve lifts were adjusted with the aid a mechanism utilizing the stock rocker weaponries and bolts and were measured utilizing a graduated Dial Gauge.
Table 1: Specification of Diesel engine
Engine Parameters Value
Bore ( millimeter ) 85.0
Stroke ( millimeter ) 76.6
Displacement ( milliliter ) 436
Number of Cylinder 1
Maximum intake valve unfastened ( millimeter ) 10.4
Intake valve diameter ( millimeter ) 38.1
Intake Valve Stem 7
When qualifying the flow through an engine, non-dimensional parametric quantities such as volumetric efficiency, discharge coefficient, flow coefficient, swirl coefficient and swirl ration provide a description of the external respiration public presentation. The usage of non-dimensional parametric quantities allows experimenters to take the size effects from the informations and compare assorted design based on geometry [ 5 ] .
The discharge coefficient, Cd is defined to be the mensural mass flow rate over the ideal mass flow rate as defined by an isentropic nose:
( 1 )
Where the characteristic country, Aci is
( 2 )
Dvalve is the interior place diameter of the valve and Li is the valve lift. The characteristic speed vc, is defined by a compressible flow speed equation
vc ( 3 )
The discharge coefficient is used to foreground low lift valve lift public presentation due to the choice of the characteristic country to reflect the minimal country between the valve and place lips
The flow coefficient, Cf, has a similar definition to Cd, but high spots higher valve lift public presentation:
( 4 )
The characteristic speed follows equation outlined before but the country defined otherwise:
( 5 )
This country is changeless across all valve lifts and is based off of the interior place diameter of the valve. When used in concurrence with Cd, the inactive flow parametric quantities allow for a description of the flow limitation in the system.
( 6 )
Swirl Coefficient is defined which basically compares the flow ‘s angular impulse with its axial impulse. For the paddle wheel, the swirl coefficient Cs is defined by
( 7 )
Where is the paddle wheel angular speed ( =2?Np, where Np is the rotational velocity )
Swirl ratio is defined as the ratio of circumferential air velocity in the cylinder to the axial velocity of the air flow in the cylinder.
( 8 )
Circumferential air velocity in the cylinder is calculated utilizing,
? — n ( 9 )
Axial velocity of the air flow in the cylinder is calculated utilizing,
( 10 )
Theoretical volumetric flow rate across the system is calculated utilizing orifice metre equation as,
( 11 )
=100000 N/ M2
= 288.7 K
Fig 1: Map and MAF detector mounting
An Agilent Data Acquisition unit, 34970A measured the trial electromotive force of MAP and MAF detector, ambient temperature, and frequence with real-time end product through an Agilent information lumberman. The trial parametric quantities were recorded for 60 seconds per valve lift for seven blower velocities so as to obtain a quotable time-averaged electromotive force. The valve lifts set were 3.5mm, 4.5mm, 5.5mm, 6.5mm, 8mm, 9mm, and 10.4mm. The flow bench and trial electromotive force informations were post-processed through Microsoft Excel to find the non-dimensional parametric quantities and swirl ratio.
Fig 2: Mechanism for traveling Paddle wheel
Fig 3: Valve Lift Mechanism
Fig 4: Experimental Apparatus
The Rpm of the Paddle wheel is found from frequence by
The line count of the flow metre used was 22.
RESULTS AND DISCUSSIONS
The informations acquired from the flow metre, paddle wheel and mass flow rate detector was used to find the discharge, flow and swirl coefficient and whirl ratio. The non-dimensional parametric quantities are discussed in the followers
Fig 5: Mass Flow Rate With/Without Flow Meter
The whirl arranger was utilized for all the flow bench trials to mensurate the frequence while supplying a negligible force per unit area bead across the instrument. Any important force per unit area loss the instrument would be reflected in a alteration in mass flow rate. Since the difference in mass flow rate from the trials with and without the arranger is within the scope of mistake, the arranger was left in topographic point for all steady flow trials.
Fig 6: Cadmium Vs. L/D for Diesel and other alteration
The coefficients of discharge ( Cd ) of the flow bench trial flow from this experiment consequence are shown in Fig 6. The Cd probe is based on difference force per unit area and valve lift per diameter. Coefficient of discharge in this experiment consequences show that, increasing the force per unit area and valve lift from 0L/D until 0.28L/D or 0mm until 10.4mm for consumption valve lift can diminish the coefficient of discharge in the intake Cd.
Fig 7: Cf Vs. L/D for Diesel and other alteration
Furthermore, the graphs depict the general tendency of coefficient of discharge for consumption from 0L/D until 0.28L/D is diminishing and after 0.28L/D is stable or horizontal. The experimental consequences showed that, increasing the valve lift can diminish the coefficient of discharge in consumption manifold, but after the maximal valve lift, the coefficient of discharge is stable and does non diminish significantly.
The Flow coefficients ( Cf ) of the flow bench trial flow from this experiment are besides at the same time shown in Fig 7. The Cf probe is based on difference force per unit area and valve lift per diameter. Flow coefficient calculated from the experimental consequences showed that, increasing the force per unit area and valve lift from 0L/D until 0.28L/D or 0mm until 10.4mm for consumption valve lift can increase the flow coefficient in the consumption Cf. The graphs besides depict the general tendency of flow coefficient for consumption from 0L/D until0.28L/D is increasing and after 0.28L/D is stable or horizontal. The experimental consequences showed that, increasing the valve lift and trial force per unit area can increase the flow coefficient in consumption manifold, but after the maximal valve lift, the flow coefficient is stable and does non demo important addition. However, in the modified Diesel engine there is a little alteration in the tendency after 0.21L/D. The discharge and flow coefficients are non stable as in the old two instances and dips significantly until 0.23L/D.The Flow coefficient for the Diesel engine fitted with shroud has about the same value as that of the normal Diesel engine, but at higher valve lifts it drops behind the normal Diesel engine. In the Diesel engine fitted with distorted tape the Flow coefficient is greater than the other two engine caput constellations up to 0.21L/D and dips significantly. The tallness of the shroud allowed the shroud to remain within the port during maximal valve lift, but non blockade the consumption smuggler during low lift.
Fig 9: Swirl Coefficient Vs. L/D
Fig 9 shows the steady-state whirl measurings of the Diesel engine. The swirl coefficient additions with increasing valve lifts, reflecting the diminishing impact of the flow limitation between the valve caput and place. It is apparent from the graph of the Diesel ( Twisted Tape ) caput that the swirl coefficient becomes greater than the Diesel caput at 0.15L/D ratio. The swirl coefficient for the Diesel ( Shroud ) caput becomes more than the diesel caput at L/D ratio 0.17L/D.The swirl coefficient obtained is maximal for the Diesel ( Twisted Tape ) and its extremum value is at 0.21L/D or 8mm valve lift. The consequence of debut of distorted tape and shroud in valve is clearly apparent from the fig 9.The debut of both distorted tape and shroud proved to increase the swirl coefficient at higher valve lifts ( & A ; gt ; 0.18L/D ) , but at lower valve lifts it provided a well less value.The Swirl ratio curves measured on the steady flow bench are presented in fig 10 as a map of valve lift/Diameter. The consequences shows that whirl ratio for original diesel caput additions as the valve lift increases up to 0.15L/D, afterwards it falls and so increases.But the general tendency of the curve is increasing. The maximal swirl ratio of 7.87 is obtained at 0.27L/D or 10.4mm valve lift fir the Diesel caput inserted with a distorted tape. It was besides found that the modified Diesel caput ( distorted Tape ) had more whirls ratio than diesel caput for higher valve lifts ( & A ; gt ; 0.15 L/D ) and had lesser whirl ratio for lower valve lifts. On the other manus, the whirl ratio for the modified Diesel ( shroud ) besides follows a similar tendency as that of the distorted tape. But the overall whirl ratio obtained for the Diesel ( shroud ) caput is less than the Diesel caput inserted with a distorted tape. It can be besides seen from the fig 10 that the diesel caput fitted with a shroud provided about the same whirl ratio as that that of the normal diesel caput at lower valve lifts, but at higher valve lifts ( ? 0.15L/D ) provided a significantly improved swirl ratio doing it more efficient than the distorted tape.
Fig 10: Swirl Ratio Vs. L/D
Fig 11: Valve Lift Vs. Crank Angle ( Diesel )
Fig 12: Swirl Ratio Vs. Crank Angle After Intake ( Diesel )
A steady flow analysis was performed on a Piaggio Ape Diesel caput to find a planetary position of the in-cylinder flow. The flow and swirl coefficient provided information about the flow rate in the cylinder by the consumption manifold and to analyze and compare the effects of debut of assorted alterations to port and valve. The usage of Swirl in Diesel is to chiefly advance more rapid commixture between the inducted air and the injected fuel.
The major decisions that can be drawn are
( 1 ) The experimental consequences showed that, the mass flow rate and flow coefficient in the consumption port of four shot Diesel engine provided the best values in the maximal valve lift per diameter 0.27L/D. It besides seen that, increasing the valve lift can increase the air flow, diminish the coefficient of discharge and increase the Flow coefficient in consumption manifold system.
( 2 ) The addition in swirl coefficient with increasing valve lifts reflects the diminishing impact of the flow limitation between the valve caput and place. It was found that the swirl coefficient obtained for the Diesel ( shroud ) and Diesel ( Twisted tape ) is greater than the original caput more L/D ratio & A ; gt ; 0.15, but at lower valve lifts is significantly lesser.
( 3 ) The maximal swirl ratio of 7.87 is obtained at 10.4mm valve lift for Diesel caput inserted with a distorted tape. The diesel caput fitted with shroud proved to be more effectual than the caput inserted with a distorted tape. The consequence was more outstanding at lower valve lifts. However at higher valve lifts the caput inserted with a distorted tape had more swirl ratio.