It’s been known for many years that thermal temperature gradients across a rotor can alter the amplitude and phase of synchronous vibration. This is due to bowing of the shaft caused by a temperature difference between one side of the shaft and the other. The earliest published recognition of this phenomenon was by Newkirk [1], where the temperature difference was a result of frictional heating...

Rayleigh-Bénard convection in rotating spherical shells can be considered as a simplified analogue of many astrophysical and geophysical fluid flows. Here, we use threedimensional direct numerical simulations to study this physical process. We construct a dataset of more than 200 numerical models that cover a broad parameter range with Ekman numbers spanning 3 × 10−7 ≤ E ≤ 10−1, Rayleigh number...

In this paper, the construction and operation of a measuring bench for vibration state rotating shaft evaluation measurement results are presented. The design was aimed at generated by excitation effects on shaft. effect imbalance position disc characteristics is shown in diagrams. It also observed that higher speeds plotted shows an irregular shape. This due to whole structure.

We tested a new rotational thrombectomy catheter in acute thrombi formed both in vitro and in vivo. The catheter consisted of a rounded platinum tip, 0.025 inch diameter by 0.08 inch long, attached to a flexible steel guidewire supported by an external sheath. In vitro, the force required to penetrate thrombus was reduced fivefold by rotation of the catheter at 4000 rpm (0.75 +/- 1.2 g rotating...

This paper presents an active bearing for reducing the radiated noise of rotating machinery. This modular bearing uses piezo stacks for actuation and both force and acceleration measurements as sensing signals. The bearing is tested on an experimental test bed comprising a rotating shaft, which is mounted in a frame. Noise is radiated by a plate that is attached to the frame. The set-up is desi...

We present a numerical study of axisymmetric flow in a rotating annulus in which local thermal forcing, via a heated annular ring on the outside of the base and a cooled circular disk in the centre of the top surface, drives convection. This new configuration is a variant of the classical thermally-driven annulus, where uniform heating and cooling are applied through the outer and inner sidewal...

The primary goal of the this project was to demonstrate the feasibility of detecting changes in shaft natural frequencies (such as those associated with a shaft crack) on rotating machinery in electric power generation plants using non-contact, nonintrusive measurement methods. During the operation of power plant equipment, torsional natural frequencies are excited by turbulence, friction, and ...

Rotating cavitation is one of the flow instabilities associated with cavitation, which has been a problem for the development of turbopumps of liquid rocket engines since it causes super-synchronous shaft vibration. Recently, it is argued that rotating cavitation might also cause large repetitive stresses on blades. This paper describes about the theoretical prediction of unsteady blade forces ...