\documentclass[11pt,a4paper,twocolumn]{article}
\usepackage{amsmath}
\usepackage[top=25mm, bottom=25mm, left=20mm, right=20mm]{geometry}
\begin{document}
\begin{align}
&\frac{\dot{m}\sqrt{R/\gamma}}{A_e}\left(\frac{\sqrt{\acute{T}_{0i,s}}}{\acute{P}_{0i,s}}\right)^{Mr_s}\cdot\left(\frac{\sqrt{\acute{T}_{0i,h}}}{\acute{P}_{0i,h}}\right)^{Mr_h}=\nonumber\\
&\sigma \cdot\cos{\beta_e}\acute{M_e} \times \left(1+\frac{\gamma-1}{2})(\acute{M}_e)^2\right)^{-\frac{(\gamma+1)}{2(\gamma-1)}} \nonumber\\
&{\scriptstyle
\left[\left(1-\frac{U^2_i-U^2_e}{2C_p\acute{T_{0i,s}}}\right)^{Mr_s}\cdot \left(1-\frac{U^2_i-U^2_e}{2C_p\acute{T_{0i,h}}}\right)^{Mr_h}\right]^{-\frac{(\gamma+1)}{2(\gamma-1)}}
}
\end{align}
\end{document}