Experimental study of damping characteristic of shrouded blade

To master the rules in shrouded blade design, an experimental system, including plane-shrouded blade, exciting system and measurement system, was designed to measure dynamic responses of non-rotating shrouded blade exactly, in which initial normal load can be put on the friction interface by a load disc accurately. The dynamic response of the first bending mode of the shrouded blade with various shroud contact angles and shroud situations were measured under different initial normal loads on the interface and different exciting force. The effects of the normal preload, shroud contact angle and shroud situation on the friction damping are analyzed from the test results. The results indicate that there is an optimal preload under which the shroud contact can provide optimum performance in dissipating vibratory energy for a given exciting force, and the larger is the relative motion between the interfaces, the more is the dissipating vibratory energy. Some laws that must be obeyed in the design of shroud contact angle and shroud situation are also concluded. The experimental results can be used to verify the theoretical and numerical results.