What Are the Steps for Calculating Boundary Layer Thickness on an Aircraft Wing?

Click For Summary
SUMMARY

The discussion focuses on calculating the boundary layer thickness (δ) at a specific location (x = 0.3m) on an aircraft wing for various velocities (20, 40, 60, 80, and 100 knots). The Reynolds number (Re) is calculated using the formula Re = ρux/μ, with values provided for air density (P = 101325 Pa), specific gas constant (R = 287 J/(kg·K)), temperature (T = 288.5 K), and dynamic viscosity (μ = 18 x 10^-6 kg/(m·s)). The boundary layer thickness is determined using the equations δ Laminar = x 4.91 Re^-0.5 and δ Turbulent = x 0.381 Re^-0.2, with transition occurring at Re = 5 x 10^5.

PREREQUISITES
  • Understanding of Reynolds number calculation
  • Familiarity with boundary layer theory
  • Knowledge of laminar and turbulent flow characteristics
  • Basic principles of fluid dynamics
NEXT STEPS
  • Study the derivation and application of the Reynolds number in fluid mechanics
  • Learn about the characteristics and equations governing laminar and turbulent boundary layers
  • Explore computational fluid dynamics (CFD) tools for simulating boundary layer behavior
  • Investigate the impact of wing design on boundary layer development and transition
USEFUL FOR

Aerospace engineers, fluid dynamics researchers, and students studying aerodynamics will benefit from this discussion, particularly those focused on boundary layer analysis in aircraft design.

ra180
Messages
8
Reaction score
0
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.
 
Physics news on Phys.org
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.
 

Similar threads

What Equation Models Boundary Layer Thickness in Early Stage Pipe Flow?
  • · Replies 6 ·
Replies
6
Views
10K