Vibration and noise analysis of gearbox for NTK 500/37 wind turbine

摘要

The overall aim was to to develop methods for the description of the structure-borne noise-source strength of wind turbine gearboxes. A gearbox manufactured by Jahnel-Kestermann for a 500 kW ''Nordtank'' wind turbine was examined. Intensive vibration tests of the gearbox were carried out at the test bed at the manufacturer's factory and nose emission from the wind turbine was measured when the gearbox had been remounted. The main results of the study are presented. Vibration measurements made on the gearbox for NTK 500/37 showed an average velocity level at the tooth mesh frequency of the output gear stage of L(sub v) = 105 dB / 1 nm/s on the input bearing housing in load conditions corresponding to a wind speed of 8 m/s, 10 m above ground. Evaluation of the influence of load on the gearbox vibration showed a minimum velocity level at a torque corresponding to a wind speed of 6 - 7 m/s, 10 m above ground (160 kW). This is evaluated as ideal. Velocity levels at the harmonics of the tooth mesh frequencies may change by more than 10 dB in a speed range close to the operational speed. Changes are due to natural vibration modes in the gearbox structure. After remounting of the gearbox, noise measurements showed a noise emission level of L(sub WA,ref) = 99 dB / 1 pW. Tonal components were identified in the noise spectrum at frequencies corresponding to the 1st and 3rd harmonics of the tooth mesh frequency of the output gear stage (approx. 604 Hz, and 1808 Hz). Noise transmission of structure born noise from the gearbox to the exterior of the wind turbine was evaluated as average. (AB)