to measure the speed of an airplane, a narrow strip heater is attached to the wing of an airplane 0.01 m from the leading edge. a heat flux of 300 w/m2 is electrically dissipated and the temperature difference between the heater and the surrounding air is measured to be 1 oc. assume that the temperature of the wing is uniform. what is the speed of the aircraft?



Answer :

Qwdog

The speed of the aircraft with a narrow strip heater attached = 370.97 m/s

The distance of the strip heater attached to the wing from the leading

edge, x = 0.01 m

Heat flux, q = 300 W/m²

The temperature difference between the heater and surrounding air,

ΔT = 1°C

The properties of the air are

   The density of air, ρ = 1 kg/m³

   Specific heat at constant pressure, CP = 1 kJ /kg K

   Thermal conductivity, k = 0.02 W/mk

   Viscosity, ν = 1.5 x 10⁻⁵ m²/s

Dynamic viscosity,

                                μ = ρ.ν

                                   = 1 x 1.5 x  10⁻⁵

                                  = 1.5 x  10⁻⁵ N s / m²

           

Prandtl number,

                         [tex]\displaystyle P_r =\frac{\mu. CP}{k}[/tex]

                              = 1.5 x 10⁻⁵ x 1 x 10³ / 0.02

                              = 0.75

Heat flux,

               q = hₓ ΔT

           300 =  hₓ x 1

              hₓ  = 300 W / m² C

So, the local Nusselt number is

                      [tex]\displaystyle Nu_x = 0.332 Re_x^{1/2} P_r^{1/3}[/tex]

                 

                      [tex]\displaystyle \frac{h_x.x}{K} = 0.332 \frac{v.x}{\nu}^{1/2}P_r^{1/3}[/tex]

    where v is the velocity of the aircraft

                        [tex]\displaystyle\frac{300 * 0.01}{0.02} = 0.332 \left( \frac{v*0.01}{1.5 * 10^{-5}}\right)^{1/2} (0.75)^{1/3][/tex]

                       

By further simplifying, we get

                 

                          150 = 0.332 x 0.9085 x 25.82 x [tex]v^{1/2}[/tex]

                              v = 370.97 m/s

Therefore, the speed of the aircraft is 370.97 m/s

Learn more about the strip heater in

https://brainly.com/question/15329813

#SPJ4

Other Questions