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The compressible Reynolds Equation (RE) is typically integrated within a fully-coupled dynamical foil-air bearings (FABs)-rotor system via spatial discretisation transformation e.g. Finite Difference (FD), Finite Element (FE). An alternative way of integrating the RE is through Galerkin Reduction (GR). The motivation for using GR is the computational benefit coming from the drastic condensation of the problem due to the elimination of the two-dimensional grid used for the air film in FD or FE. This paper presents a novel application of arbitrary-order GR to both nonlinear and linearised analyses of rotor systems supported by single-pad FABs with variable radial clearance (preload). Simulations using FD gave close correlation with those using GR for all preloads, with discrepancies increasing as the preload approaches the nominal clearance (c). The simulations show that the preload has to exceed a certain level in order to delay the onset of instability speed (OIS), and significant delay in OIS and suppression of sub-synchronous vibration is possible when the preload is comparable to c. Experimental validation is provided.

Typically, accelerometer-based vibration measurements of rotating machinery are conducted with sensors mounted to a static part of the machine. Now, with increasing accuracy of compact and low powered microelectromechanical systems (MEMS) accel erometers, on-shaft vibration measurements have become an interesting research topic. MEMS sensors are optimal for internet of things (IoT) applications and wireless measurements, which makes on-shaft measurements more convenient. However, typically in wireless applications, the sample clock is time-based, and thus the data is not bound to the phase of the rotating rotor. In this research, a novel wireless sensor unit with an inverse encoder is mounted to the end of a large rotor to investigate the dynamic behavior of the rotor. In addition, a method to separate the vertical and hori zontal vibration from the sensor data is studied.