Abstract Geared contra-rotating open rotors have the potential to further reduce fuel consumption relative geared turbofans, but require a more-complex speed-reducing transmission system drive propellers. Hitherto, preliminary design for such systems has been reported independently of overall engine modeling or limited by many predetermined constraints. This restricted feasible space systems. A...

Artiicial neural networks provide a means of capturing stationary statistical information about machine vibrations in the form of non-linear autoregressive models. These models can be used as one step ahead pre-dictors allowing comparison of signals for the purposes of fault detection and diagnosis. From the prediction error, features can be extracted and used to determine the machine's conditi...

A B S T R A C T Pump shafts used for power generation are susceptible to fatigue cracking while often in near-continuous operation. Technology based on torsional vibration is under development for condition-based assessment of shaft health. The focus of this paper is on the relationship between a crack, which propagated due to bending loads, and the torsional stiffness of the shaft. An analytic...

Torsional vibrations and resonance problems with synchronous machines are most frequently encountered in rotor systems with long shafts and large inertias constituting a weakly damped mechanical resonator which exhibits a low resonance frequency. It is impossible to obtain a effective mechanical damping for these torsional vibrations, but by using a power electronics device and an inductive or ...

Traditional linear spectral analysis techniques of the vibration signals, based on auto-power spectrum, are used as common tools of rotating components diagnoses. Unfortunately, linear spectral analysis techniques are of limited value when various spectral components interact with one another due to nonlinear or parametric process. In such a case, higher order spectral (HOS) techniques are reco...

Clearance forming between rotating shafts and radial lip seals has been investigated both numerically and experimentally at various temperature conditions. Numerical models of clearance forming has been developed taking in account the effect of temperature, defining the material constituting properties according to empiric WLF function. Experiments have been performed with a special apparatus t...