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Estimation of speed dependent fault parameters in a coupled rotor-bearing system

Lal M., Satapathy M.

Archive of Mechanical Engineering

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2018

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Vol. LXV, nr 3

327--347

EN

In rotating machineries, misalignment is considered as the second most major cause of failure after unbalance. In this article, model-based multiple fault identiﬁcation technique is presented to estimate speed-dependent coupling misalignment and bearing dynamic parameters in addition with speed independent residual unbalances. For brevity in analysis, a simple coupled rotor bearing system is considered and analytical approach is used to develop the identiﬁcation algorithm. Equations of motion ingeneralized co-ordinates are derived with the help of Lagrange’s equation and least squares ﬁtting approach is used to estimate the speed-dependent fault parameters. Present identiﬁcation algorithm requires independent sets of forced response data which are generated with the help of diﬀerent sets of trial unbalances. To avoid/suppress the ill-conditioning of regression equation, independent sets of forced response data are obtained by rotating the rotor in clock-wise and counter clock-wise directions, alternatively. Robustness of algorithm is checked for diﬀerent levels of measurement noise.

2

Application of reconstruction of variational iteration method on the laminar flow in a porous cylinder with regressing walls

Azimi M., Hedesh A. M., Karimian S.

Mechanics and Mechanical Engineering

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2017

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Vol. 21, nr 2

379--387

EN

A study of an incompressible two-dimensional flow in a channel with one porous wall is presented in this research. As usual, the cylindrical propellant grain of a solid rocket motor is modeled as a long tube with one end closed at the headwall, while the other remains open. The governing continuity and momentum equations together with the associated boundary conditions are first reduced to a set of self similar non-linear coupled ordinary differential equations using similarity transformations. Then we solved the ordinary differential equation by RVIM and the numerical method.

3

Flow Modeling in a Porous Cylinder with Regressing Walls Using Semi Analytical Approach

Azimi M., Hedesh A. M., Karimian S.

Mechanics and Mechanical Engineering

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2014

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Vol. 18, nr 2

77--84

EN

In this paper, the mathematical modeling of the flow in a porous cylinder with a focus on applications to solid rocket motors is presented. As usual, the cylindrical propellant grain of a solid rocket motor is modeled as a long tube with one end closed at the headwall, while the other remains open. The cylindrical wall is assumed to be permeable so as to simulate the propellant burning and normal gas injection. At first, the problem description and formulation are considered. The Navier–Stokes equations for the viscous flow in a porous cylinder with regressing walls are reduced to a nonlinear ODE by using a similarity transformation in time and space. Application of Differential Transformation Method (DTM) as an approximate analytical method has been successfully applied. Finally the results have been presented for various cases.