# Find the circulation on the airfoil.

An airfoil generates a lift of 80 N when operating in a free stream flow of 60 m/s.If the ambient pressure and temperature are 100 kPa and 290 K respectively ( specific gas constant is 287 J/kg-K),the circulation on the airfoil is

Here first we need to calculate the air density.

\(P=\rho RT

\\\rho =\frac{P}{RT}

\\=\frac{10^{5}}{287\times 290}

\\=1.2014\;kg/m^{3}\)

On applying Kutta-Joukowski theorem:

\({L}’=\rho V\tau

\\\Rightarrow \tau =\frac{80}{1.2014\times 60}

\\=1.11\;m^{2}/s\)

Therefore circulation on the airfoil is \(1.11\;m^{2}/s\).