Boundary Thickness Questions

1. Jul 29, 2014

ra180

Calculate the thickness of the boundary Layer δ at a location x= 0.3m along the chord length of an aircraft wing at each of the following velocities. (u = 20, 40,60,80,100 knots)

Assume ISA P=101325 R=287 T=288.5 μ =18 x 10-6

(1)Re transition=5 x 10^5
(2)δ Laminar = x 4.91 Rex^-0.5
(3)δ turbulent = x 0.381 Re^-0.2

Using Re= ρux/μ

Re(20) =21008 Re (40)= 420175 Re (60)=630262 Re (80)= 840350 Re (100)= 1050233

I'm not to sure where to go from here, do I have to substitute the Reynolds into the three equations if so which values do substitute.

2. Jul 29, 2014

Travis_King

You know the reynold's numbers for each case, you know the characteristic length (x), you are given the Reynold's number for which the flow transitions from laminar to turbulent over a flat plate (the wing), and the equations for the boundary layer thickness for both states (laminar and turbulent).

This one's a plug and chug, once you identify which streams are laminar and which are turbulent.