Radiation efficiency of submerged finite stiffened cylindrical shell

The theoretical solutions of the average radiation efficiency of submerged finite stiffened or unstiffened cylindrical shell are derived by using modal summation method. The relationship between fluid loaded finite unstiffened cylindrical shell and the equivalent rectangular plate is analyzed. And the differences between light and heavy fluid loaded cylindrical shell about modal wavenumber graphs and radiation characteristics are investigated. Then, the semi-empirical formulae of average radiation efficiency of the submerged finite unstiffened cylindrical shell are presented. Numerically compared with theoretical solutions, the semi-empirical formulae can well reflect the trend or mean values of average radiation efficiency, especially in medium-high frequency range. On this basis, the semi-empirical formulae are expanded to the case of stiffened cylindrical shell by introducing some modification factors that are related to the amount of the stiffeners and the mass ratio of the stiffeners to the shell. The expanded semi-empirical formulae are validated numerically with different shell sizes or stiffener numbers.