# Calculate Reynolds Number for NACA 4412 Wing

• solar.spectrum
In summary, to calculate the Reynolds number for your NACA 4412 wing, you will need to use the formula Re = ρVD/μ with the characteristic length of the wing being (2/3) * (a + b) * 1.193. The Reynolds number for your wing would be 262481.3 times the sum of the wingroot and wingtip lengths.
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

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.

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.

## 1. What is the formula for calculating the Reynolds Number for a NACA 4412 wing?

The formula for calculating Reynolds Number for a NACA 4412 wing is Re = (ρ*V*c)/μ, where Re is the Reynolds Number, ρ is the density of the fluid, V is the velocity of the fluid, c is the chord length of the wing, and μ is the viscosity of the fluid.

## 2. What is the significance of the Reynolds Number in aerodynamics?

The Reynolds Number is a dimensionless quantity that represents the ratio of inertial forces to viscous forces in a fluid flow. It is used to determine the type of flow (laminar or turbulent) around an object and is crucial in predicting the aerodynamic behavior of an airfoil or wing.

## 3. How do I determine the values for density, velocity, and viscosity in the Reynolds Number equation?

The values for density, velocity, and viscosity can be determined experimentally or through numerical simulations. Depending on the specific conditions and environment, these values can also be estimated using known properties of the fluid and assuming certain conditions.

## 4. What is the standard range for Reynolds Number for a NACA 4412 wing?

The standard range for Reynolds Number for a NACA 4412 wing is typically between 1 million and 10 million. However, this can vary depending on the specific application and desired outcomes.

## 5. How does the Reynolds Number affect the lift and drag of a NACA 4412 wing?

The Reynolds Number has a significant impact on the lift and drag of a NACA 4412 wing. At lower Reynolds Numbers, the flow is typically laminar, resulting in lower drag but also lower lift. At higher Reynolds Numbers, the flow is more turbulent, resulting in higher drag but also higher lift. Finding the optimal Reynolds Number for a specific wing design is crucial in achieving the desired aerodynamic performance.