Environmental Engineering Reference
In-Depth Information
Fig. 12.7
Wind turbine with tuned sloshing damper (a) and tuned liquid column damper (b)
Further research is needed for a better prognosis of the efficiency of this damper
for the wind turbines. A more stable vibration mitigation process can be achieved
by TLCD, which is described in the following section. Figure
12.7
shows a wind
turbine with a TSD.
12.3.4.2 Tuned Liquid Column Dampers
The TLCD, patented in 1910 by Frahm, consists of a U-shaped tank, which is filled
similar to TSD with a Newtonian liquid [
15
]. Originally invented to mitigate
rolling motions of ships, the TLCD counts as one the first damping devices. The
vibration energy of the oscillating damper liquid dissipates by turbulence effects
and friction caused local pressure loss. In civil engineering, TLCD became known
first after the publications and patent application by Sakai [
29
]. In addition to low
material and maintenance costs, because of the geometric flexibility, TLCD is
assumed to be a better choice compared to other damping measures, particularly
for slender structures like wind turbines.
Mathematical Description
Figure
12.8
shows a TLCD attached to a horizontally excited structure. The liquid
motion and oscillation effects can be derived with the nonlinear Bernoulli equa-
tion, whereas the natural frequency of the liquid damper depends only on the
geometry of the tank.
