Vibration Dampers

Particularly when operating in stall, the aerodynamic damping of the edgewise vibrational modes of the blades may be very low or even negative, causing large vibrations and corresponding oscillatory loads. To prevent this, some blades are fitted with vibration dampers. These consist of a mass-spring-damper system tuned to vibrate at the resonant frequency. To activate the vibration damper, set the Vibration damper present checkbox in the Blades screen under the Additional Mass/Inertia tab. When using this feature in Bladed, the same vibration damper is applied to each blade. The following options are available:

Table 1: Overview of vibration damper inputs in Bladed

Property	Description	Unit
Blade station	The blade station where the vibration damper is located.	\(\bunit{-}\)
Angle to chord line	The angle of the damper relative to the chord line.	\(\bunit{deg}\)
Damper mass	The mass of the vibration damper.	\(\bunit{kg}\)
Frequency	The frequency at which the damper is tuned to vibrate.	\(\bunit{Hz}\)
Damping factor	The damping factor, expressed as a fraction of critical damping.	\(\bunit{-}\)

Enter the mass, frequency, damping factor (fraction of critical damping), damper position, and direction of vibration relative to the local chord line. For the direction, the sign convention is the same as for blade Aerodynamic twist.

Last updated 05-12-2024