G. Olmi¹

Structural Durability & Health Monitoring, Vol.8, No.1, pp. 61-90, 2012, DOI:10.3970/sdhm.2012.008.061

Abstract Turbogenerator rotors and coil retaining rings are highly loaded components, under low cycle fatigue at every machine switch on and switch off transient. Their failure during service may lead to very serious consequences. The present paper utilizes several experimental data, concerning the static, cyclic and fatigue behaviour of the rotor material, in order to perform a probabilistic analysis. All the main methodological issues are tackled, consisting in the experimental data processing, in the choice of the random variables that are involved in the fatigue process, in the determination of their distributions, in the practical computation of the probability of failure… More >

Hyun Ki¹, Jongwook Choi², Sungcho Kim²

The International Conference on Computational & Experimental Engineering and Sciences, Vol.13, No.4, pp. 69-70, 2009, DOI:10.3970/icces.2009.013.069

Abstract The wake behind rotor blade is investigated by numerical and experimental approaches. Flow structure measured through PIV is compared with numerical analysis using commercial program of ANSYS CFX adopting the RNG k-ε turbulence model. Blade model fabricated by Rapid-Prototype method has the cross section of NACA0012 airfoil and the pitch angle of 10°. The rectangular blade of which rotating diameter (D) and chord length are 0.12 m and 0.024 m respectively rotates at 240 rpm. Horizontal and vertical directions of the blade are selected as x and z coordinates, respectively, the origin locates at the rotating center, and measurement range… More >

Seawook Lee¹, Leesang Cho², Jin-Soo Cho³

The International Conference on Computational & Experimental Engineering and Sciences, Vol.7, No.3, pp. 113-122, 2008, DOI:10.3970/icces.2008.007.113

Abstract Computational methods based on the solution of the flow model are widely used for the analysis of low-speed, inviscid, attached-flow problems. Most of such methods are based on the implementation of the internal Dirichlet boundary condition. In this paper, the time-domain panel method uses the piecewise constant source and doublet singularities. The present method utilizes the time-stepping loop to simulate the unsteady motion of the rotary wing blade for the KHP. The wake geometry is calculated as part of the solution with no special treatment. To validate the results of aerodynamic characteristics, the typical blade was chosen such as, Caradonna-Tung… More >

N. Lesaffre¹, J-J. Sinou¹, F. Thouverez¹

The International Conference on Computational & Experimental Engineering and Sciences, Vol.2, No.4, pp. 101-110, 2007, DOI:10.3970/icces.2007.002.101

Abstract This paper presents a model of flexible beams rotating on the inner surface of an elastic stationary ring. The beams possesses two degrees of freedom, traction/compression and flexure. The in-plane deformations of the ring are considered and a single mode approximation is used. The model has been developed within the rotating frame by use of an energetic method. To better understand the phenomena occurring, the degrees of freedom of the beams can first be treated separately then together. Stability analysis show that even without rubbing, the radial degree of freedom of a beam rotating on an elastic ring can create… More >

Bing Li^1,2, Hongbo Dong¹

CMES-Computer Modeling in Engineering & Sciences, Vol.84, No.3, pp. 205-228, 2012, DOI:10.3970/cmes.2012.084.205

Abstract Different from single crack identification method, the number of cracks should be firstly identified, and then the location and depth of each crack can be predicted for multiple cracks identification technology. This paper presents a multiple crack identification algorithm for rotor using wavelet finite element method. Firstly, the changes in natural frequency of a structure with various crack locations and depths are accurately obtained by means of wavelet finite element method; and then the damage coefficient method is used to determine the number and region of cracks. Finally, by finding the points of intersection of three frequency contour lines in… More >

Jyoti Ranjan Majhi, Ranjan Ganguli¹

CMES-Computer Modeling in Engineering & Sciences, Vol.27, No.1&2, pp. 25-36, 2008, DOI:10.3970/cmes.2008.027.025

Abstract The flapping equation for a rotating rigid helicopter blade is typically derived by considering 1) small flap angle, 2) small induced angle of attack and 3) linear aerodynamics. However, the use of nonlinear aerodynamics can make the assumptions of small angles suspect. A general equation describing helicopter blade flap dynamics for large flap angle and large induced inflow angle of attack is derived in this paper with nonlinear aerodynamics . Numerical simulations are performed by solving the nonlinear flapping ordinary differential equation for steady state conditions and the validity of the small angle approximations are examined. It is shown that… More >

F. Simonetti¹, R. M. Ardito Marretta²

CMES-Computer Modeling in Engineering & Sciences, Vol.1, No.3, pp. 81-90, 2000, DOI:10.3970/cmes.2000.001.383

Abstract Advanced propellers are being developed to improve the performance and fuel economy of future transport aircraft. To study them, various aerodynamic prediction models and systems (from theory to experiment) have been developed via several approaches (Free Wake Analysis, helicoidal source methods, scale model tests). This study focuses on the development of an efficient numerical method to predict the behaviour of rotor or propeller in forward flight. Based on a variational approach, the present numerical technique allows a significant reduction of computer resources used in the calculation of instantaneous velocities to determine the wake geometry and the three-dimensional vortex flow streaming… More >

Rooh ul Amin¹, Irum Inayat², Li Aijun¹, Shahaboddin Shamshirband^3,4,*, Timon Rabczuk⁵

CMC-Computers, Materials & Continua, Vol.57, No.3, pp. 365-388, 2018, DOI:10.32604/cmc.2018.03757

Abstract A bio-inspired global finite time control using global fast-terminal sliding mode controller and radial basis function network is presented in this article, to address the attitude tracking control problem of the three degree-of-freedom four-rotor hover system. The proposed controller provides convergence of system states in a pre-determined finite time and estimates the unmodeled dynamics of the four-rotor system. Dynamic model of the four-rotor system is derived with Newton’s force equations. The unknown dynamics of four-rotor systems are estimated using Radial basis function. The bio-inspired global fast terminal sliding mode controller is proposed to provide chattering free finite time error convergence… More >