Time domain damping identification in helicopter rotor systems

2001 ◽  
Author(s):  
Yongsheng Zhao ◽  
Norman Wereley
Keyword(s):  
Time Domain ◽  
Helicopter Rotor ◽  
Rotor Systems

Modelling and simulation of a compliant tilting pad air bearing

2015 ◽  
Vol 230 (1) ◽  
pp. 69-87 ◽  
Author(s):  
Frans Duijnhouwer ◽  
Henk Nijmeijer
Keyword(s):  
Dynamic Simulation ◽  
Time Domain ◽  
Linear Time ◽  
Simulation Models ◽  
Time Domain Analysis ◽  
Air Bearing ◽  
Rotor Systems ◽  
Tilting Pad ◽  
Non Linear ◽  
Dynamic Simulation Model

The compliant tilting pad air bearing concept, a tilting pad bearing with the pivot of the pads placed on radial springs, is a promising aerodynamic bearing solution. Nevertheless, its non-linear dynamics make a time domain dynamic simulation model an essential tool for the design of rotor systems with these bearings. Development of these dynamic simulation models is the subject of this paper that provides a detailed description of an extendible model of the compliant tilting pad air bearing concept suitable for non-linear time domain analysis. 2D and 3D time domain simulations implementing the model are discussed in detail and some of their capabilities to model the non-linear behaviour of the bearing concept are demonstrated with examples.

Extracting of Micro Doppler Parameter of Helicopter Rotor Based on Time-Frequency Analysis

2011 ◽  
Vol 130-134 ◽  
pp. 2696-2700 ◽  
Author(s):  
Lei Zhang ◽  
Guo Qing Huang
Keyword(s):  
Frequency Domain ◽  
Frequency Analysis ◽  
Time Domain ◽  
Good Method ◽  
Helicopter Rotor ◽  
Echo Signal ◽  
Time Frequency Analysis ◽  
Time Frequency ◽  
Radar Echo ◽  
Doppler Parameter

The micro Doppler effect of the radar echo signal of helicopter rotor is studied, and the formula of helicopter rotor echo is obtained. Then the received echo signal of helicopter rotor simulated is analyzed in time domain, frequency domain and time-frequency domain respectively, the analysis results show that it is a good method to extract micro Doppler of helicopter rotor echo by time-frequency analysis. According to analysis results, obtained a method to determine parity of blades and velocity of helicopter rotor, these methods can be used to identify helicopter.

scholarly journals Design and analysis trends of helicopter rotor systems

Sadhana ◽  
1994 ◽  
Vol 19 (3) ◽  
pp. 427-466 ◽  
Author(s):  
Inderjit Chopra
Keyword(s):  
Helicopter Rotor ◽  
Rotor Systems

Interaction Between Unbalance and Misalignment Responses in Flexibly Coupled Rotor Systems Integrated With AMB

2017 ◽  
Author(s):  
Rangavajhala Siva Srinivas ◽  
Rajiv Tiwari ◽  
Ch. Kanna Babu
Keyword(s):  
Time Domain ◽  
Beam Element ◽  
Active Magnetic Bearings ◽  
Full Spectrum ◽  
Flexible Coupling ◽  
Rotor Systems ◽  
Jeffcott Rotor ◽  
Vibration Attenuation ◽  
Modeling Techniques ◽  
Rotor Dynamic

This paper studies the rotor dynamic behavior of misaligned-coupled rotor systems integrated with active magnetic bearings. The simplest possible numerical model has been derived with a 4-degree of freedom two coupled Jeffcott rotor systems. The effect of flexible coupling on the interaction between the response due to unbalance and misalignment has been studied. To demonstrate the influence three cases have been considered a) pure misalignment b) pure unbalance c) presence of both unbalance and misalignment. This is an original attempt considering the standard practice of using beam element based finite element modeling techniques for such systems. To simplify the problem, the weight dominance of discs has been assumed. Also the coupling considered in the problem is of flexible type. Misalignment in coupled rotors has been reported in literature to produce all harmonics both odd and even (...−2, −1, 0, 1, 2...) on either side of full spectrum. A suitable coupling excitation function has been chosen so that the response yields all the harmonics in spectrum. The numerical simulation has been performed in MATLAB/SIMULINK™ to generate the responses in time domain. Though AMB is incorporated in the system for vibration attenuation, the emphasis of the present paper shall be to demonstrate the interplay between unbalance and misalignment in flexibly coupled rotor systems.

Static and Dynamic Balancing of Helicopter Tail Rotor Blade Using Two-Plane Balancing Method

2014 ◽  
Vol 71 (2) ◽  
Author(s):  
Mohd Shariff Ammoo ◽  
Ziad Abdul Awal ◽  
Norhidayah Mat Sangiti
Keyword(s):  
Life Span ◽  
Rotor Blade ◽  
Stability Control ◽  
Rotor System ◽  
Helicopter Rotor ◽  
Vibration Level ◽  
Dynamic Balancing ◽  
Rotor Systems ◽  
Entire Vehicle

Balancing is a rotating component is critical in any mechanism. Devoid of proper balancing, any vehicle - be it in air, land or sea, it will affect stability, control and safety. The same goes for rotor crafts. Imbalance of the helicopter tail rotor system leads to vibrations in the entire vehicle and may cause accident. Typically, for the tail rotor of a helicopter, the blade is a source of vibration on the tail boom. This not only causes inconvenience to the pilot but also reduces the life span of the helicopter. There is a certain amount of vibration in the helicopter rotor systems especially the tail rotor. Hence, balancing procedure for rotating mass was conducted to reduce the vibration. This research focuses on balancing of the tail rotor for UTM Single Seat Helicopter. Experiments have been conducted in order to study the vibration level of the tail rotor. Adding and removing masses separately on the tail rotor exhibited different vibration levels. The responses were analyzed and used for balancing the tail of rotor system. The balancing effort was considered successful, although there was still some residual unbalance in the tail rotor.

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