We report results from Direct Numerical Simulation (DNS) of rotating Rayleigh-Bénard convection, regarding the scaling of heat transfer with the Rayleigh number for rotating systems at a fixed rate of rotation. The Prandtl number, Pr = 6.4, is kept constant. We perform simulations, using a spectral element method, for Rayleigh numbers Ra from 10 to 10, and Rossby numbers Ro from 0.09 to∞. We fi...

Unbalance and misalignment are the commonly occurring faults in rotating mechanical systems. These faults are caused mainly due to improper installation or premature failure of the machine components. Detection and diagnosis of faults in rotating machinery is crucial for its optimal performance. In this study artificial neural networks (ANN) and support vector machine (SVM) techniques have been...

In this paper energy method is used to calculate rotor response with loose rotating disk on it. System equation of motion is obtained based on energy method and Lagrange equation. Mathematical modeling of loose disk in a rotor bearing system has resulted in terms similar to unbalance and gyroscopic effect in the system equation of motion. The effect of loose disk axial position and orthotropic ...

Acoustic Emission (AE) is being extensively used as a Non Destructive Technique (NDT) for diagnosis of rotating components. The main theory behind this diagnosis is that while rotation, acoustic energy level of defective portion in rotating element is different. In the present study a signal processing technique is proposed to identify the variation in acoustic signal and results are verified f...

In recent years, as a rule, improvement of the reliability of liquid propellant rockets becomes an international technical problem for built-up of safe space transport systems. The high performance, liquid propellant rocket engines require high-pressured turbopumps to deliver extremely low temperature propellants of liquid oxygen (LO2, boiling point 90 K) and liquid hydrogen (LH2, boiling point...

This paper describes experimental and numerical procedures to estimate friction torque on a rotating shaft due to radial elastomeric seals. Two different test rigs have been built, in order to highlight the relationship between the overall friction and the local behaviour of each lip portion in presence of dynamic eccentricities. A direct measurement has been performed with a rotating shaft mac...

A plain journal bearing is spontaneously unstable above a critical speed and loses much of its load carrying capacity when subjected to a load rotating at about half the speed of the shaft. The almost axially symmetric flow in a compressor can break down at low flow into a rotating pattern of stall cells but only the special case of a single propagating stall cell gives rise to a mechanical cou...

Many systems can be approximated as linear with coefficients that vary periodically with time. For example, an anisotropic shaft rotating at constant speed on anisotropic bearings can be modeled as periodically time varying (PTV). Similar models can be obtained for wind turbines, some mechanisms, etc... However, the vast majority of modal analysis algorithms and techniques apply only to linear ...

This paper presents an axisymmetric rotational inertia shaker for reducing the structure borne noise radiated by rotating machinery. This modular inertia shaker uses a piezostack to generate a compensating force on a rotating element by accelerating a ring shaped mass. The piezostack is controlled using an adaptive shunt circuit, which emulates the impedance of a variable inductance. The inerti...