Calculate Reynolds Number for NACA 4412 Wing

[solar.spectrum]

hey guys, I would like to know about reynold's number for a wing

I have designed a NACA 4412 wing which has wingroot = a , wingtip = b and winglet tip = c (a,b,c are any integers or decimals)

please tell me the formula of calculating D for the eqn of reynolds number = ρVD/μ


additional info : Wing taper ratio = 0.3 , sweep and sweepback angle = 37 degree

altitude = 6000m , density = 0.65970 kg/m3, Pressure = 47182.5 Pa ,
Temp= 249.2K , velocity of freestream= 100m/s, viscosity= 0.00001594 N sec/m^2

 

[RandomGuy88]

For a wing the length scale for the Reynolds number is typically the mean aerodynamic chord of the wing.

http://en.wikipedia.org/wiki/Chord_(aircraft)#Mean_aerodynamic_chord

however you can also use the root chord or the tip chord or any thing in between really. The choice depends on what you are interested in. However the convention for a wing is the mean aerodynamic chord so I am assuming that is probably what you want.

 

[NatSusan]

Hi there,

To calculate the Reynolds number for your NACA 4412 wing, you will need to use the formula:

Re = ρVD/μ

Where:
- Re = Reynolds number
- ρ = density of the fluid (in your case, 0.65970 kg/m3)
- V = velocity of the freestream (in your case, 100m/s)
- D = characteristic length of the wing (in your case, the average chord length of the wing)
- μ = dynamic viscosity of the fluid (in your case, 0.00001594 N sec/m^2)

To calculate the characteristic length of your wing, you can use the formula:

D = (2/3) * c * ((1+taper ratio)/(1+taper ratio^2))

Where:
- c = average chord length of the wing (in your case, it would be the average of wingroot and wingtip)
- taper ratio = wing taper ratio (in your case, 0.3)

Using the given values, we can calculate the characteristic length of your wing as follows:

D = (2/3) * (a + b) * ((1+0.3)/(1+0.3^2))
= (2/3) * (a + b) * (1.3/1.09)
= (2/3) * (a + b) * 1.193

Now, substituting this value in the Reynolds number formula, we get:

Re = (0.65970 kg/m3) * (100m/s) * ((2/3) * (a + b) * 1.193) / (0.00001594 N sec/m^2)
= 262481.3 * (a + b)

Therefore, the Reynolds number for your NACA 4412 wing would be 262481.3 times the sum of the wingroot and wingtip lengths (in meters).

I hope this helps! Let me know if you have any further questions.