\documentclass{article}
\usepackage[demo]{graphicx}
\usepackage{subfigure}

\begin{document}

\begin{figure}[h]
%\centering
\subfigure[]{
\includegraphics[width=73mm]{location_cl}
\label{position_cl}
}
\hspace*{0.5mm}
\subfigure[]{
\includegraphics[width=73mm]{location_cd}
\label{position_cd}
}
\vspace*{0.5mm}
\subfigure[]{
\includegraphics[width=73mm]{location_clcd}
\label{position_clcd}
}
\caption{The effect of Gurney flap position on aerodynamic coefficients of pitching airfoil}
\label{flap_position}
\end{figure}

\end{document}