Ans:
- Intake:
- In
the PV diagram, an air-fuel mixture is drawn into the cylinder as the piston
moves from top dead center (TDC) to the bottom dead center (BDC) at nearly
constant pressure. This is represented by a horizontal line at low
pressure.
- In
the TS diagram, there is an isentropic compression as air is drawn into
the cylinder and its entropy remains nearly constant while temperature
increases slightly.
- Compression:
- In
the PV diagram, the piston compresses the air-fuel mixture adiabatically
(without heat transfer) as it moves from BDC to TDC. This is represented
by an upward-sloping line with increasing pressure and decreasing volume.
- In
the TS diagram, the compression process is represented by a steep upward
slope as entropy decreases while temperature and pressure increase.
- Power:
- In
the PV diagram, ignition of the compressed mixture leads to a rapid
increase in pressure and volume expansion as the piston moves from TDC to
BDC. This is the power stroke, represented by a downward-sloping line.
- In
the TS diagram, this expansion process corresponds to an isentropic
expansion, characterized by a downward slope with entropy remaining
nearly constant while temperature and pressure decrease.
- Exhaust:
- In
the PV diagram, the exhaust valve opens, and the piston pushes out the
remaining exhaust gases during the exhaust stroke, resulting in a
near-constant pressure and increasing volume.
- In
the TS diagram, the exhaust process corresponds to an isentropic expansion,
similar to the power stroke, but in the reverse direction.
These diagrams illustrate the changes in pressure, volume,
temperature, and entropy during each stage of the Otto Cycle, providing a
visual representation of the engine's thermodynamic behavior.
Tappet clearance is a critical adjustment in internal
combustion engines, particularly in those with mechanical valve lifters or
overhead camshaft (OHC) configurations. It needs to be set correctly to ensure
the engine operates smoothly and efficiently. If the tappet clearance is too
large (excessive), the valve may not fully close, leading to loss of
compression and poor performance. If the clearance is too small (insufficient),
the valve may not fully open, causing poor engine performance, overheating, or
damage to the valve and camshaft.
The specific tappet clearance values and adjustment
procedures vary depending on the engine's design and manufacturer, so it's
essential to consult the engine's service manual or follow the manufacturer's
guidelines when performing this adjustment. Modern engines often use hydraulic
lifters that automatically adjust the clearance, eliminating the need for
regular manual adjustments.
The stress-strain curve of mild steel typically exhibits the following key characteristics:
- Elastic
Region: At low levels of stress, mild steel behaves elastically, meaning
it returns to its original shape when the applied stress is removed. In
this region, the material follows Hooke's law, and the stress is directly
proportional to the strain.
- Yield
Point: As the stress increases, mild steel reaches a point called the
yield point. At this point, the material undergoes plastic deformation,
meaning it deforms permanently even after the stress is removed. The yield
point marks the beginning of plasticity in the material.
- Plastic
Region: Beyond the yield point, mild steel continues to deform plastically
as the stress increases further. The stress-strain curve shows a gradual
increase in strain with a relatively constant stress level in this region.
- Ultimate
Tensile Strength (UTS): The stress-strain curve reaches its peak stress at
the ultimate tensile strength (UTS). This is the maximum stress the
material can withstand before it begins to fracture.
- Necking
and Fracture: After reaching the UTS, mild steel undergoes necking, where
the cross-sectional area of the specimen decreases significantly, leading
to a reduction in stress. Finally, the material fractures at the point
where the stress becomes too great for it to support.
In summary, the stress-strain curve of mild steel starts
with an elastic region, followed by plastic deformation, reaching the yield
point, and then progressing to the ultimate tensile strength before eventual
fracture. This curve is crucial for understanding the mechanical behavior of
mild steel under different loading conditions.
find D2 (driven pulley diameter).
N1D1 = N2D2, but there's a
calculation error in the final step:
D2 = (N1 * D1) / N2 D2
= (1400 * 5) / 800 D2
= 7000 / 800 D2
= 8.75 inches
So, the correct diameter of the driven pulley (D2) is 8.75 inches.
