The low-speed wind tunnel experiment is carried out on a simplified aircraft model to explore the influence of wing flexibility on the aircraft aerodynamic performance.The investigation involves the measurements of fo...The low-speed wind tunnel experiment is carried out on a simplified aircraft model to explore the influence of wing flexibility on the aircraft aerodynamic performance.The investigation involves the measurements of force,membrane deformation and velocity field at Reynolds number of 5.4×10^(4)-1.1×10^(5).In the lift curves,two peaks are observed.The first peak,corresponding to the stall,is sensitive to the wing flexibility much more than the second peak,which nearly keeps constant.For the optimal case,in comparison with the rigid wing model,the delayed stall of nearly5°is achieved,and the relative lift increment is about 90%.It is revealed that the lift enhanced region corresponds to the larger deformation and stronger vibration,which leads to stronger flow mixing near the flexible wing surface.Thereby,the leading-edge separation is suppressed,and the aerodynamic performance is improved significantly.Furthermore,the effects of sweep angle and Reynolds number on the aerodynamic characteristics of flexible wing are also presented.展开更多
The interaction between membrane structures and their environment can be either static or dynamic. Static interaction refers to interaction with static air, while dynamic interaction refers to wind and its effects. Th...The interaction between membrane structures and their environment can be either static or dynamic. Static interaction refers to interaction with static air, while dynamic interaction refers to wind and its effects. They can be evaluated by two parameters, added mass and radiation/aerodynamic damping, which are experimentally investigated in this study. The study includes the effects of both the static and dynamic interaction on structural dynamic characteristics, and the relationship between the interaction parameters and the covered area of a membrane structure for the static interaction and the relationship between the interaction parameters and wind direction and speed for the dynamic interaction. Experimental data show that the dynamic interaction is strongly correlated with the structural modes, i.e., the interaction of the symmetric modes is much larger than the anti-synmletric modes; and the influence of the dynamic interaction is significant in wind-induced response analysis and cannot be ignored. In addition, it is concluded that the structural natural frequency is remarkably decreased by this interaction, and the frequency band is significantly broadened.展开更多
针对某车型排气尾管低频噪声大问题,利用GT-Power软件建立发动机工作过程与排气消声器耦合仿真分析模型,对排气消声器声学性能和空气动力学性能进行数值计算,分析排气尾管低频噪声大的原因。依据分析结果提出消声器结构优化方案,制作优...针对某车型排气尾管低频噪声大问题,利用GT-Power软件建立发动机工作过程与排气消声器耦合仿真分析模型,对排气消声器声学性能和空气动力学性能进行数值计算,分析排气尾管低频噪声大的原因。依据分析结果提出消声器结构优化方案,制作优化样件进行整车排气尾管噪声试验。试验结果表明,低转速时消声器插入损失提高5d B^7 d B(A),2阶次噪声整体降低,低频噪声问题明显改善。展开更多
Civil aviation faces great challenges because of its robust projected future growth and potential adverse environmental effects. The classical Tube-And-Wing(TAW) configuration following the Cayley’s design principles...Civil aviation faces great challenges because of its robust projected future growth and potential adverse environmental effects. The classical Tube-And-Wing(TAW) configuration following the Cayley’s design principles has been optimized to the architecture’s limit, which can hardly satisfy the further requirements on green aviation. By past decades’ investigations the BlendedWing-Body(BWB) concept has emerged as a potential solution, which can simultaneously fulfill metrics of noise, emission and fuel burn. The purpose of the present work is to analyze the developments of critical technologies for BWB conceptual design from a historical perspective of technology progress. It was found that the high aerodynamic efficiency of BWB aircraft can be well scaled by the mean aerodynamic chord and wetted aspect ratio, and should be realized with the trade-offs among stability and control and low-speed performance. The structure concepts of non-cylinder pressurized cabin are of high risks on weight prediction and weight penalty. A static stability criterion is recommended and further clear and adequate criteria are required by the evaluations of flying and handling qualities. The difficulties of propulsion and airframe integration are analyzed. The energy to revenue work ratios of well-developed BWB configurations are compared,which are 31.5% and 40% better than that of TAW, using state-of-art engine technology and future engine technology, respectively. Finally, further study aspects are advocated.展开更多
基金supported by the National Natural Science Foundation of China(Nos.11761131009 and 11721202)。
文摘The low-speed wind tunnel experiment is carried out on a simplified aircraft model to explore the influence of wing flexibility on the aircraft aerodynamic performance.The investigation involves the measurements of force,membrane deformation and velocity field at Reynolds number of 5.4×10^(4)-1.1×10^(5).In the lift curves,two peaks are observed.The first peak,corresponding to the stall,is sensitive to the wing flexibility much more than the second peak,which nearly keeps constant.For the optimal case,in comparison with the rigid wing model,the delayed stall of nearly5°is achieved,and the relative lift increment is about 90%.It is revealed that the lift enhanced region corresponds to the larger deformation and stronger vibration,which leads to stronger flow mixing near the flexible wing surface.Thereby,the leading-edge separation is suppressed,and the aerodynamic performance is improved significantly.Furthermore,the effects of sweep angle and Reynolds number on the aerodynamic characteristics of flexible wing are also presented.
基金National Natural Science Foundation of China Under Grant No. 50725826, 90815021
文摘The interaction between membrane structures and their environment can be either static or dynamic. Static interaction refers to interaction with static air, while dynamic interaction refers to wind and its effects. They can be evaluated by two parameters, added mass and radiation/aerodynamic damping, which are experimentally investigated in this study. The study includes the effects of both the static and dynamic interaction on structural dynamic characteristics, and the relationship between the interaction parameters and the covered area of a membrane structure for the static interaction and the relationship between the interaction parameters and wind direction and speed for the dynamic interaction. Experimental data show that the dynamic interaction is strongly correlated with the structural modes, i.e., the interaction of the symmetric modes is much larger than the anti-synmletric modes; and the influence of the dynamic interaction is significant in wind-induced response analysis and cannot be ignored. In addition, it is concluded that the structural natural frequency is remarkably decreased by this interaction, and the frequency band is significantly broadened.
文摘针对某车型排气尾管低频噪声大问题,利用GT-Power软件建立发动机工作过程与排气消声器耦合仿真分析模型,对排气消声器声学性能和空气动力学性能进行数值计算,分析排气尾管低频噪声大的原因。依据分析结果提出消声器结构优化方案,制作优化样件进行整车排气尾管噪声试验。试验结果表明,低转速时消声器插入损失提高5d B^7 d B(A),2阶次噪声整体降低,低频噪声问题明显改善。
基金supported by the Fundamental Research Funds for the Central Universities (Nos. 3102019JC009 and G2016KY0002)
文摘Civil aviation faces great challenges because of its robust projected future growth and potential adverse environmental effects. The classical Tube-And-Wing(TAW) configuration following the Cayley’s design principles has been optimized to the architecture’s limit, which can hardly satisfy the further requirements on green aviation. By past decades’ investigations the BlendedWing-Body(BWB) concept has emerged as a potential solution, which can simultaneously fulfill metrics of noise, emission and fuel burn. The purpose of the present work is to analyze the developments of critical technologies for BWB conceptual design from a historical perspective of technology progress. It was found that the high aerodynamic efficiency of BWB aircraft can be well scaled by the mean aerodynamic chord and wetted aspect ratio, and should be realized with the trade-offs among stability and control and low-speed performance. The structure concepts of non-cylinder pressurized cabin are of high risks on weight prediction and weight penalty. A static stability criterion is recommended and further clear and adequate criteria are required by the evaluations of flying and handling qualities. The difficulties of propulsion and airframe integration are analyzed. The energy to revenue work ratios of well-developed BWB configurations are compared,which are 31.5% and 40% better than that of TAW, using state-of-art engine technology and future engine technology, respectively. Finally, further study aspects are advocated.
