An equivalent unbalance identification method for the balancing of nonlinear squeeze-film damped rotordynamic systems

Improved non-invasive inverse problem method for the balancing of nonlinear squeeze-film damped rotordynamic systems

“…The nonlinearity of these bearings comes from the oil film that surrounds the non-rotating outer race of the rolling element bearings. As stated in [3,1], the LP rotor is relatively easy to balance by traditional methods (discussed below). On the other hand, the HP rotor cannot be accessed under operational conditions because of the restricted space for instrumentation and high temperatures.…”

“…On the other hand, the HP rotor cannot be accessed under operational conditions because of the restricted space for instrumentation and high temperatures. Hence, in order to monitor a state of unbalance that develops in the HP rotor during its operational lifetime, a non-invasive procedure that is based on vibration measurements at the engine casing, rather than the rotor, is required [3,1] which would then facilitate a "right first time" corrective action. Fig.1.…”

“…The second part of the validation shows that the novel enhanced explicit inverse problem method is essential for effective balancing of this previously unconsidered system. Repeatability and robustness to noise/model uncertainty are satisfactorily demonstrated and limitations discussed.The identification of the rotor unbalance from vibration measurements at the casing and/or the rotor is referred to as an "inverse" problem [3], in contrast to the "forward" problem, which refers to the prediction of the system vibration in response to a known unbalance distribution. Traditional balancing methods (which include the standard "trim" balancing procedures) [4][5][6][7][8] involve the use of several trial runs and the application of trial masses at fixed balancing planes.…”

“…The methods of Krodkiewski et al [10] and Ding et al [11] find the change in unbalance from one rotor condition to another using a known rotordynamic model which can include nonlinear models for the bearings.However, these methods are still invasive since they require that the motion of the rotor journals relative to the bearings can be measured before and after the change in unbalance. Accordingly, many subsequent efforts have focused on non-invasive inverse problem procedures for identifying the unbalance, which require of prior knowledge of the structure (obtained from modelling or experiment) as in [12][13][14][15][16], [1,3]. The methods of [12][13][14][15][16] were based on a linear bearing model.…”

Rotor dynamic balancing control method based on fuzzy auto-tuning single neuron PID

“…Cedillo, S.G.T. and P. Bonello [6] put forward an equivalent unbalance identification method for the balancing of nonlinear squeeze-film damped rotor dynamic systems. Beltran-Carbajal, F., G. Silva-Navarro and M. Arias-Montiel [7] put forward an active control scheme based on compensation of perturbation force signals to balance rotating machinery with unknown system parameters and variable operation speed.…”