Answer to Question #200269 in Mechanical Engineering for Ash

Question

Why need to add kinetic energy correction factor in the Bernoulli’s equation? How do you

determine the kinetic energy correction factor? Explain briefly. What is the difference between

pipe, tube and duct? Define water hammer.

Answer 1

a) The kinetic energy correction factor in the Bernoulli's equation is necessary once viscosity is introduced as a parabolic velocity profile develops in a pipe, with v=0 along the edge and v_max=2v_avg in the center. Therefore, kinetic correlation factor, α=2 is necessary in correcting the average velocity.

b) Both terms can be equated by multiplying the correction factor on the average velocity side. Hence, the correction factor is equal to the actual total kinetic energy divided by the kinetic energy found using average velocity.

c)Pipe

Pipe is used mostly to transport liquids and semi-liquids.

Tubes

Tubes is used mostly for heat transfer purpose.

Duct

Duct is used for air and flue gas transport.

d) Water hammer is a knocking noise in a water pipe that occurs when a tap is turned off briskly.