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Shang X.-S.,Navel Academy of Armament | Wu Z.-F.,The 31st Research Institute of CASIC | He Y.-F.,CPLA 8.1 Parachute Brigade
Tuijin Jishu/Journal of Propulsion Technology

Solid rocket motor underwater test parameters change dramatically and signals often overlap severely. In order to solve the problem arisen due to this in data processing, the denoising method based on soft threshold wavelet transform was proposed and the analysis and processing of data for testing the thrust of solid rocket motor under water was performed. Comparison with conventional method shows that this method can divid dynamic data into the approximate component to reflect 'low frequency' characteristics and the detail components to reflect the 'high frequency' characteristics. This method is convenient for analysis of the motor performance test data. Variation characteristics of the data can be well retained in the simultaneous removal of test data interference. It can meet the requirements of the engineering application for data processing in solid rocket motor underwater test. Source

Liu Y.-X.,Beijing Institute of Technology | Nie L.-C.,The 31st Research Institute of CASIC | Zhang J.,Beijing Institute of Technology | Yang X.,Beijing Institute of Technology
Tuijin Jishu/Journal of Propulsion Technology

In order to improve effects of gas generator flow regulation, a pressure closed loop control system was built. The working principle was analyzed, and the dynamic model of the system was established. According to the characteristics of the system model, linear active disturbance rejection controller (LADRC) was designed to control it. Because of the extended state observer, LADRC can compensate the effect caused by parameter fluctuation on the output well in a larger range. It improves the speed of response and the control accuracy. Simulation results in different working conditions show that LADRC shortens 30% adjustment time, and reduces about 50% output caused by interference. It has better dynamic characteristics than the traditional controller. © 2015, Journal of Propulsion Technology. All right reserved. Source

Yang S.,Wuhan Naval University of Engineering | Sun K.-Q.,The 31st Research Institute of CASIC
Tuijin Jishu/Journal of Propulsion Technology

A space-time conservation element and solution element method(CE/SE) was used to simulate the formation and propagation process of two-dimensional detonation ignited by hotspot, and analyze the detonation mechanism and the factors to hotspot ignition. For the hotspot ignition, the initial pressure was 0.1 MPa and temperature was different. Implicit trapezoidal technique was established to handle stiff source term. Results show that the uniform temperature and linear temperature distribution of hotspot have different detonation mechanism, which is effected by the varied parameters in ignition zone. The large region size, the linear temperature distribution or the shape of hemisphere for the hotspot could induce detonation easily. The results offer reference to study detonation ignition. Source

Zhao L.,Tongji University | Zhao L.,The 31st Research Institute of CASIC | Hu C.,Tongji University | Hu C.,Yangzhou University
Gongcheng Lixue/Engineering Mechanics

Based on elastodynamics, employing the complex function and conformal mapping method, elastic wave scattering and dynamic stress concentrations in exponentially graded materials with a cavity of arbitrary shape have been investigated and an analytical solution of the problem has been derived.The numerical results of the dynamic stress concentration factors around the elliptical cavity are presented as an example. The effects of elastic wave-number and heterogeneous parameters of the materials on the dynamic stress concentration factors are analyzed. Source

Zhao W.,The 31st Research Institute of CASIC | Liu Z.-D.,The 31st Research Institute of CASIC | Li S.-B.,Beihang University
Tuijin Jishu/Journal of Propulsion Technology

In order to reveal the unsteady flow mechanism of compressor blade boundary layer under rotor/stator aerodynamic interaction, numerical simulation was applied to investigate the unsteady boundary layer flow of the stator at the mid-span in a high loading transonic fan stage. Critical parameters, including skin friction, turbulence kinetic energy and static pressure fluctuation on the blade surface, were analyzed in detail to describe the unsteady effects of the high loaded stator boundary layer based on the model of rotor wake/potential-stator boundary layer interaction. The numerical results show that the bypass transition would occur in the stator boundary layer during the impinging of the rotor wake. And also, a pressure fluctuation would propagate with the speed of sound along the blade boundary layer after the leading edge was impinged by the wake. The distribution of the pressure and friction along the whole pressure side and the leading edge of the suction side were affected by the pressure fluctuation propagation. The pressure fluctuation effect was determined by the pressure gradient and the blade surface shape. Source

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