Thailand Excellence Community
Vehicle dynamics
Factors affecting vehicle dynamics…
Factors affecting lateral force / side slip dependency:
Powertrain – Power transmission
Engine-to-wheel torque transmission
Performances: acceleration, top speed, gradeability
Create/Read Vehicle Performance Graph.
Traction force diagram
Performance determination: graphical approach
Braking performances
Lateral vehicle dynamics
Forces and motions mainly in lateral direction
Predicting cornering performances, handling, stability…
Drivetrain and braking
Automobile layout
Powertrain
Braking system
3.Distribution of mass
Center of mass
Moment of inertia
Roll moment
Sprung mass
Unsprung mass
Weight distribution
Aerodynamics
Automobile drag coefficient
Automotive aerodynamics
Center of pressure
Downforce
Ground effect in cars ***
*** see also,
This kind of ground effect is easily illustrated by taking a tarpaulin out on a windy day and holding it close to the ground: it can be observed that when close enough to the ground the tarp will be drawn towards the ground. This is due to Bernoulli’s principle; as the tarp gets closer to the ground, the cross sectional area available for the air passing between it and the ground shrinks. This causes the air to accelerate and as a result pressure under the tarp drops while the pressure on top is unaffected, and together this results in a net downward force. The same principles apply to cars.
The Bernoulli principle is not the only mechanic in generating ground effect downforce. A large part of ground effect performance comes from taking advantage of viscosity. In the tarp example above neither the tarp nor the ground is moving. The boundary layer between the two surfaces works to slow down the air between them which lessens the Bernoulli effect. When a car moves over the ground the boundary layer on the ground becomes helpful. In the reference frame of the car, the ground is moving backwards at some speed. As the ground moves, it pulls on the air above it and causes it to move faster. This enhances the Bernoulli effect and increases downforce. It is an example of Couette flow.
While such downforce-producing aerodynamic techniques are often referred to with the catch-all term “ground effect”, they are not strictly speaking a result of the same aerodynamic phenomenon as the ground effect which is apparent in aircraft at very low altitudes.
Analysis and simulation
Other……
2.
ที่ความเร็วคงที่ใดๆ ทุกเกียร์ใช้กำลังเท่ากัน = กำลังจากแรงต้านทั้งหมด