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Su Y.,Harbin Engineering University | Chen Q.,China Helicopter Research and Development Institute | Shen H.,Harbin Engineering University | Lu W.,Harbin Engineering University
Journal of Marine Science and Application

Planing vessels are applied widely in civil and military situations. Due to their high speed, the motion of planning vessels is complex. In order to predict the motion of planning vessels, it is important to analyze the hydrodynamic performance of planning vessels at high speeds. The computational fluid dynamic method (CFD) has been proposed to calculate hydrodynamic performance of planning vessels. However, in most traditional CFD approaches, model tests or empirical formulas are needed to obtain the running attitude of the planing vessels before calculation. This paper presents a new CFD method to calculate hydrodynamic forces of planing vessels. The numerical method was based on Reynolds-Averaged Navier-Stokes (RANS) equations. The volume of fluid (VOF) method and the six-degrees-of-freedom equation were applied. An effective process was introduced to solve the numerical divergence problem in numerical simulation. Compared with experimental results, numerical simulation results indicate that both the running attitude and hydrodynamic performance can be predicted well at high speeds. © 2012 Harbin Engineering University and Springer-Verlag Berlin Heidelberg. Source

Wang Y.,China Helicopter Research and Development Institute
American Helicopter Society International - 2nd Asian/Australian Rotorcraft Forum, ARF 2013 and the 4th International Basic Research Conference on Rotorcraft Technology 2013, IBRCRT 2013

A new active fuzzy control method in the time-domain on vibration control of smart rotor with trailing-edge flap is presented in this paper. The mathematic model of the rotor system with four elastic blades is built up. An aerodynamics model is utilized to predict the incremental trailing-edge flap's airloads. The fuzzy control algorithm is developed and analyzed for the mathematic model of a hingeless rotor system. Comparing with other control algorithms in previous researches, the fuzzy control algorithm is more suitable to the vibration reduction of smart rotor and more effective. Numerical studies show that the hub vertical vibration loads can be significantly reduced by 98%. This paper provides a theoretical basis for future design and experiment. Source

Wu D.-P.,Nanjing University | Cheng W.-P.,China Helicopter Research and Development Institute | Yu S.-L.,Nanjing University
Guangdian Gongcheng/Opto-Electronic Engineering

To enhance Camshift algorithm on the adaptability of high-speed object, complex background and covering, an improved algorithm combining inter-frame difference and motion prediction is proposed. First, before calculating back-projection image, the color information is associated with the motion information gained from inter-frame difference to eliminate color noise and automatically initialize tracking. Second, in order to make the algorithm applicable with high-speed object, position of target is predicted and searching window is updated according to tracking state. Experimental results prove that the improved algorithm is robust to high-speed target, covering and color noises. Source

Shi S.,Northwestern Polytechnical University | Li L.,China Helicopter Research and Development Institute | Liang J.,Harbin Institute of Technology | Tang S.,Northwestern Polytechnical University
International Journal of Heat and Mass Transfer

An irreversible ablation process of a silica fiber reinforced polymer (SiFRP) composite under various thermal conditions was investigated using a numerical and experimental study. Both an oxyacetylene torch and a solar radiant heating facility were developed and used to simulate the rapid heating process. A theoretical model was proposed to predict the surface ablation behavior of SiFRP composites when only steady-state ablation is considered. The accuracy of the model was evaluated by comparing calculated and experimental surface ablation recession rate and wall temperature for a silica/phenolic composite. The effect of variable thermal and transport properties on ablation behavior was analyzed. Furthermore, a model for predicting the volumetric ablation behavior was presented. The heat transfer, generation of decomposition gases and their subsequent diffusion process in the internal material were simulated. This study would provide a fundamental understanding for the design of high temperature thermal protection system. © 2016 Elsevier Ltd Source

Sun W.,Nanchang University | Xiong B.-S.,Nanchang University | Huang J.-P.,China Helicopter Research and Development Institute | Mo Y.,Nanchang University
Zhendong yu Chongji/Journal of Vibration and Shock

Local mean decomposition (LMD) method is a new adaptive time-frequency analysis method, it is successfully applied in rolling bearing fault diagnosis. However, LMD method is sensitive to noise. In order to eliminate influence of noise on result of diagnosis, a fault diagnosis approach for rolling bearing based on wavelet packet de-noising and local mean decomposition (LMD) was proposed. Firstly, wavelet packet was used to remove noise from a signal. Then, the de-noised signal was decomposed with LMD, and the correlation coefficient between the PF components after decomposition and the signal befor decomposition was used as the standard of judgment, the redundant low-frequency PF components were eliminated. Finally, the effective PF set was selected to conduct the power spectral analysis and the fault features were extracted. The comparison between the simulation data and the actual rolling bearing fault diagnosis tests data showed that the proposed method is effective. Source

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