通过数值计算,详细研究了射流偏转角与主流夹角大于90°的逆主流小孔稳态射流(Reversed in jectionVG Js)对低雷诺数涡轮流动分离的控制。研究结果发现,逆主流射流对主流的扰动引起射流孔后边界层迅速转捩可抑制流动分离现象。射流...通过数值计算,详细研究了射流偏转角与主流夹角大于90°的逆主流小孔稳态射流(Reversed in jectionVG Js)对低雷诺数涡轮流动分离的控制。研究结果发现,逆主流射流对主流的扰动引起射流孔后边界层迅速转捩可抑制流动分离现象。射流作为"湍流发生器"从控制机理上有别于90°偏转角VG Js射流状态。高射流湍流度(10%),135°逆主流VG Js在达到与90°偏转角VG Js基本相同的流动分离控制效果时,可降低射流流量67%。展开更多
In order to improve the engineering performance of a novel hydraulic shock generator, the fluid flow inside its complex passages is numerically investigated. The effects of the inlet flow velocity upon the turbulenc...In order to improve the engineering performance of a novel hydraulic shock generator, the fluid flow inside its complex passages is numerically investigated. The effects of the inlet flow velocity upon the turbulence intensity of the jet flow are analyzed. The calculated pressure loss is experimentally verified with the consideration of temperature determined viscosity shifting. The results are used as the reference in the further development of the hydraulic shock generator展开更多
In some special cases of flight simulation (e.g. for formation flight, in-flight tanking) it is required to generate a two-dimensional field of turbulence, in which the turbulent wind speeds are stochastic functions o...In some special cases of flight simulation (e.g. for formation flight, in-flight tanking) it is required to generate a two-dimensional field of turbulence, in which the turbulent wind speeds are stochastic functions of two coordinates (e.g. x in the flight direction and y in the wing span direction). For this purpose a simple and efficient technique for the digital generation of a two-dimensional field of turbulence, i.e. for the production of turbulent speed sequences on a rectangular network, is proposed in this paper. The correlation of the turbulent field so generated is found to be in good agreement with the theoretical correlation of the turbulence model, and thus the feasibility of the proposed method is verified. Two possible operation modes (off-line and on-line) of the turbulence generator in flight simulation are also discussed.展开更多
基金This project is supported by National Natural Science Foundation of China! (59835160).
文摘In order to improve the engineering performance of a novel hydraulic shock generator, the fluid flow inside its complex passages is numerically investigated. The effects of the inlet flow velocity upon the turbulence intensity of the jet flow are analyzed. The calculated pressure loss is experimentally verified with the consideration of temperature determined viscosity shifting. The results are used as the reference in the further development of the hydraulic shock generator
基金This project is supported by China National Sciences Foundation and finished in the Institute of Flight Guidance of Technical University Braunschweig (West Germany).
文摘In some special cases of flight simulation (e.g. for formation flight, in-flight tanking) it is required to generate a two-dimensional field of turbulence, in which the turbulent wind speeds are stochastic functions of two coordinates (e.g. x in the flight direction and y in the wing span direction). For this purpose a simple and efficient technique for the digital generation of a two-dimensional field of turbulence, i.e. for the production of turbulent speed sequences on a rectangular network, is proposed in this paper. The correlation of the turbulent field so generated is found to be in good agreement with the theoretical correlation of the turbulence model, and thus the feasibility of the proposed method is verified. Two possible operation modes (off-line and on-line) of the turbulence generator in flight simulation are also discussed.
