Engine Design and Operating Parameters
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Transcript of Engine Design and Operating Parameters
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Engine Design and Operating Parameters
• Thermodynamic Parameters– Define indicated, brake, and friction quantities.
– Define net and gross quantities
– Calculate sfc, AF, vol. eff. and engine efficiency
– Correct performance data for atmospheric conditions.
• Geometric & Kinematic Parameters.– Define and use the different rated conditions
– Calculate engine volume, piston speed, and cylinder surface area as a function of crank angle
– Draw a cylinder schematic and identify the bore, stroke, crank radius, TDC, BDC, and crank angle
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List of Laboratory Experiments
• Study of Anatomy of A Single Cylinder Diesel Engine.
• Study of Anatomy of A Multi-cylinder Diesel Engine.
• Disassembly and assembly of A single cylinder Diesel Engine.
• Measurement of Valve Timing of A Single Cylinder Diesel Engine.
• Performance study of Single cylinder Diesel Engine.
• Performance study of Multi cylinder Diesel Engine.
• Performance study & Morse Testing of Multi cylinder (MPFI) Gasoline Engine.
• Performance study of Dual Fuel Engine.
• Measurement of p- diagram on a diesel engine.
• Measurement of coefficient of discharge of Valve as function of valve lift.
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Division of Sub Groups : Allocation of Experiments
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Simplified View of An Engine
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Anatomy of A Multi-cylinder Diesel Engine
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LUBRICATION SYSTEM
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Lubrication Networking
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Exhaust Valve : Operation Schedule
Pcyl
Patm
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Inlet Valve : Operation Schedule
PcylPatm
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Valve Actuation Diagram
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Cold Period of Operation Hot Period of Operation
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Geometry of Flow Passage through Valves
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Geometry of Valve
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Stages of Valve Lifting
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Instantaneous Valve Events
• For low lift valves, the minimum flow area corresponds to a frustum of right circular cone.
• The conical face between valve and seat is, perpendicular to the seat, defines the flow area.
0cossin
vLw
The minimum area is:
2sin
22cos v
vvm
LwDLA
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• For the second stage, the minimum area is still the slant surface of a frustum of a right circular cone.
• However, this surface is not perpendicular to the valve seat.
• The base angle of the cone increases from (900- toward that of a cylinder.
• For this stage:
cossintan
42
22
wLww
D
DDv
m
sp
2/122tan wwLDA vmm
Dm is mean diameter of seat : wDD vm
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•When the valve lift is sufficiently large, the minimum flow area is no longer between the valve head and seat.•It is the port area minus the sectional area of the valve stem.
tan4
2/1
222
wwD
DDL
m
spv
Then,
22
4 spm DDA
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Valve Lift Curves
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Frictional Compressible Flow Through Inlet Valve
• The real gas flow effects are included by means of an experimentally determined discharge coefficient CD.
• The air flow rate is related to the upstream stagnation pressure p0 and stagnation temperature T0, Static pressure just down stream of the valve and a reference area AR.
• AR is a characteristic of the valve design.
12
1
2/12/1 1
2
inlet
inletRD
RT
pACm
2
1
0
1
2/1 11
2
p
p
p
p
RT
pACm cyl
inlet
cyl
inlet
inletRD
When the flow is chocked:
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Discharge Coefficient:
idealf
actf
d
m
mC
,
,
The value of CD and the choice of reference area AR are linked together.
The product CD . AR is the effective flow area of the valve assembly, AE.
In general valve head area or port area or curtain area are used as reference areas.
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INLET VALVES
12 3
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EXHAUST VALVES