Question

Class work 1 At normal pressure, the meters per second.. find the range of critical distance watcr at a temperature of 20 degrees passes through a smooth surface at a uniform velocity of s Xc value for laminar boundary layer to turbulent boundary layer P-998.2kg/m 100.5x10s Pa s 2. At atmospheric pressure, the air at a temperature of 30 degrees passes through the surface of a smooth plate at the rate of 10m/s.. Re, is 3.2X 10, determine by calculation that it is laminar boundary layer or turbulent boundary layer at the points 0.4m and 0.8m from the leading edge of the distance plate? Find the laminar flow boundary layer thickness. ρ-1.165Kg/mr", μ-1.86 x 10"/a . s

Answer 1

1) velocity v = 5 m/s

Turbulent flow appears at a critical N_Re ( Reynolds no. )

b/w 10⁵ and 3 x 10⁶ if parallel flow along a plate

For N_Re = 10⁵

v v e / Mu = 10⁵

x x 5 x 998.2 / 100.5 x 10^-5 = 10⁵

x = 0.020136 m.

For N_Re = 3 x 10⁶

x x 5 x 998.2 / 100.5 x 10^-5 =  3 x 10⁶

x = 0.60408 m.

Range of critical distance is 0.020136 to 0.60408 m.

2 ) velocity v = 10 m / s ,  N_{Re =} 3.2 x 10⁵

At a distance 0.4 m from the leading edge

N_Re = x v e / Mu = 0.4 x 10 x 1.165 / 1.86 x 10^-5

= 2.505 x 10⁵

At 0.8 m from the leading edge