EFFECT OF SPECIFIC LOAD OF BEARING ON THE CENTRIFUGAL COMPRESSOR ROTORDYNAMIC STABILITY

With the ever increasing of the centrifugal compressor;apability, such as large scale LNG and CO2 re -injection, the ability margin evaluation and instability control is crucial both Dr the centrifugal compressor OEM and end users. An Ldustrial scale experimental test rig with two 5 -pads tilting pad iurnal bearings and two active magnetic bearings was ntroduced. Tilting pad bearings were used to support the rotor, and active magnetic bearings were used to exert static load and;ub-synchronous sine load to excite the rotor. The logarithmic -Jcrement identification method of rotor -bearing system was mresented. Here, weighted instrument variable and directional -equency response function were combined to improve antiLoise performance and separate forward/ backward whirl vibration. Thermoelastohydrodynamic bearing model was used D investigate the effect of hot clearance on the stability)rediction of centrifugal compressor. Also, the contribution of)earing specific load on the stability was studied numerically..1so, experimental work was carried out to investigate the amping ratio of rotor under different rotating speed and)earing specific loads. The numerical results correlate with the 3st results very, well. The results of the investigation indicate (i) Hot clearance is very important for centrifugal :ompressor rotordynamic instability prediction; (ii) The effect)f pad mechanical deformation are smaller than that of thermal :formation; (iii) With the increase of bearing specific load, the Dgarithmic decrement is decreasing.