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Xiang S.,Shenyang Aerospace University | Kang G.-W.,Shenyang Aerospace University | Yang M.-S.,AVIC Shenyang Engine Design and Research Institute | Zhao Y.,Shenyang Normal University
Composite Structures | Year: 2013

In the present paper, meshless global collocation method based on the thin plate spline radial basis function and nth-order shear deformation theory are used to analyze the free vibration of sandwich plate with functionally graded face and homogeneous core. Meshless global collocation method approximates the solution of governing differential equations using the all nodes in the problem domain. The third-order theory of Reddy can be considered as a special case of the present nth-order theory. Natural frequencies of the sandwich plates with various side-to-thickness ratios, thickness ratio of each layer, boundary conditions and material properties are calculated by the present nth-order theory and meshless global collocation method. The results are compared with the three dimensional Ritz solutions. © 2012 Elsevier Ltd. Source


Liu B.,Beihang University | An G.,Beihang University | Yu X.,Beihang University | Zhang Z.,AVIC Shenyang Engine Design and Research Institute
Experimental Thermal and Fluid Science | Year: 2016

Tip leakage flow is inherently an unsteady flow phenomenon, which plays an important role in compressor stability. A quantitative evaluation of the unsteady behaviors of tip leakage vortex will help reveal the effect of tip leakage flow on the compressor characteristics. In this paper, stereoscopic particle image velocimetry (SPIV) is used to investigate the unsteady behaviors of tip leakage vortex near the rotor tip region in a low-speed axial compressor test facility. By using a vortex identification method, the size, location, the number and some other parameters of the TLV in the instantaneous realizations of the SPIV results are extracted. Based on the statistical analyses of these critical parameters, the unsteady behaviors of the TLV (vortex wandering, vortex splitting, and vortex breakdown) are quantitatively evaluated. A parameter is defined to quantitatively evaluate the intensity of the tip leakage vortex wandering, and it is found that the intensity of vortex wandering increases slowly at first but then increases rapidly as the TLV propagates downstream. Vortex splitting is found to start at different streamwise locations for different mass flow rate conditions, and from the initial position of the vortex splitting the average number of TLV increases with the streamwise location. The backflow induced by the vortex breakdown in the tip leakage flow is significant in the SPIV results. At last, the effect of the TLV's wandering, splitting, and breakdown on the evolution of the blockage is also discussed. © 2016 Elsevier Inc. Source


Guo Z.-W.,AVIC Shenyang Engine Design and Research Institute | Guo Z.-W.,Beihang University | Fei C.-W.,Beihang University | Bai G.-C.,Beihang University
Tuijin Jishu/Journal of Propulsion Technology | Year: 2013

To master more effectively the impact factors on an aeroengine whole-body vibration performance, the improved Fuzzy Support Vector Machine (FSVM) information entropy technique was proposed. Firstly, the computing model of multi-class fuzzy membership was established based on the improved fuzzy membership of FSVM and the information entropy theory. And secondly, this method was applied to the aeroengine vibration performance evaluation, and the multi-parameter vibration performance analysis model was developed and the relationship between fault modes and fault causes was determined. Thus, aeroengine overall vibration performance was quantitatively analyzed and a quantitative reference index was provided for aeroengine vibration control. Finally, the validity and feasibility of this method in aeroengine whole-body vibration performance analysis were validated by mean of the fusion analysis of example. Source


Liu B.,Beihang University | An G.,Beihang University | Yu X.,Beihang University | Zhang Z.,AVIC Shenyang Engine Design and Research Institute
Experimental Thermal and Fluid Science | Year: 2016

Flow separations in compressor blade passages are common and can cause significant flow blockage and loss production. This paper investigates experimentally the three-dimensional (3D) flow separations in a highly loaded low-speed large-scale compressor facility. Oil flow visualizations, stereoscopic particle image velocimetry (SPIV), and five-hole probe measurements are conducted at certain conditions from the near-chock to near-stall condition along the compressor operating line. The 3D separation and vortex flow structures in the stator at different operating conditions are analyzed. By changing the size of the rotor tip gap, six groups of oil-flow pictures are obtained to study the effect of the rotor gaps on the 3D separating flows in the downstream stator. The variation of the corner separation scale is almost linear with the rotor tip gap size. Along the compressor operating line, four typical 3D flow structures are found inside the stator passage. Between the second typical 3D flow structure and the third typical 3D flow structure, an unstable stage exists on the compressor operating line; during this stage, the hub corner separation becomes an open separation from the closed type. A smaller rotor tip gap corresponds to an earlier unstable stage. Finally, a critical rotor tip blockage state usually existed for the transform of corner separation types at a certain rotor tip gap configuration. This discovery is valuable for the study of multistage compressor matching problems at off-design conditions. © 2016 Elsevier Inc. Source


Tian H.,Tianjin University | Sun X.,Tianjin University | Jia Q.,AVIC Shenyang Engine Design and Research Institute | Liang X.,Tianjin University | And 2 more authors.
Energy | Year: 2015

This paper proposes a segmented thermoelectric generator (TEG) that can be used to recover exhaust waste heat from a diesel engine (DE). A mathematic model of the segmented TEG was constructed based on the low-temperature thermoelectric material bismuth telluride and the medium-temperature thermoelectric material skutterudite. Performance was compared between segmented and traditional TEGs, and the performance of the segmented TEG was optimized based on the comparison. The model simulates the impact of relevant factors, including the exhaust temperature, cold source temperature, thermocouple length, and the length ratio between the two materials, on the output power and conversion efficiency. The results showed that the segmented TEG is more suitable than the traditional TEG for a high-temperature heat source and for large temperature differences. Moreover, the maximum output power was inversely proportional to the thermocouple length; however, the maximum conversion efficiency was directly proportional. The ratio of the two materials depended on the temperature of the heat and cold source. Finally, a comparison of application potential of the TEGs showed that the segmented TEG had greater potential for waste heat recovery compared with the traditional TEG. © 2015 Elsevier Ltd. Source

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