三角翼大攻角分离流开缝吸气效应研究

分别采用数值方法和实验方法研究了大后掠角三角翼大攻角条件下，背风面开缝吸气对流场结构和气动力特性所造成的影响。数值模拟采用 Ｈａｒｔｅｎ Ｙｅｅ 的二阶精度隐式 Ｔ Ｖ Ｄ 格式和 Ｎ Ｓ方程；实验采用激光蒸汽屏流场显示和应变天平测力技术。通过在三角翼背风面开缝吸气，抽掉低能气流，实现增升的效果不理想，同二维吸气涡控制增升效果相差很远，这主要是由于二维同三维分离产生机理上的差异所造成的。

中缝苍白核调制Btzinger复合体的吸气抑制效应

目的:研究中缝苍白核对Btzinger复合体吸气抑制效应的调制作用,并探讨其可能机制。方法:长串电刺激家兔Btzinger复合体,观察膈神经吸气相放电的变化。然后先长串电刺激中缝苍白核或向中缝苍白核内微量注射谷氨酸钠后,再长串电刺激Btzinger复合体,观察膈神经吸气相放电的变化,并与前对照作比较。结果:长串电刺激Btzinger复合体,膈神经吸气相放电的幅度降低。长串电刺激中缝苍白核或向中缝苍白核内微量注射谷氨酸钠后,再长串电刺激Btzinger复合体,则导致膈神经吸气相放电幅度被降低的程度减小。结论:中缝苍白核对Btzinger复合体的吸气抑制效应具有一定的调制作用,表现为使其吸气抑制效应减弱,且此调制作用呈现短时记忆性特点。

慢性阻塞性肺病患者吸气驱动效应的测定及其临床意义

为探索吸气驱动效应（ＶＴ／Ｐ０．１）与吸气肌功能的关系，对１５例正常人和６０例慢性阻塞性肺病（ＣＯＰＤ）患者进行了ＶＴ／Ｐ０．１、最大吸气口腔压（ＭＩＰ）及最大吸气中段流量（ＭＭＩＦ）的测定。结果显示：ＣＯＰＤ患者ＶＴ／Ｐ０．１值明显低于正常人，随着病情程度加重而愈趋降低，且ＶＴ／Ｐ０．１与ＭＩＰ、ＭＭＩＦ两者均呈高度正相关。表明ＶＴ／Ｐ０．１与ＭＩＰ。

翼型大攻角状态下表面吸气驻涡增升的数值模拟实验

用数值模拟方法给出了翼型大攻角状态表面吸气后绕翼型流动的某些新现象并对流场的特性进行了机理性研究,其中包括吸气对翼型背风面分离涡的驻涡增升作用;吸气孔位置对流场的影响;不同吸气强度以及间歇式吸气的增升效应。数值模拟的出发方程为N-S方程,差分格式为Beam-Warming格式。数值实验表明:(1)吸气可有效地提高翼型大攻角状态下的升力;(2)在一定吸气强度下吸气可使翼型背风面上涡的非定常脱落现象消失从而起到驻涡作用;(3)吸气孔位置在翼面的中部附近增升效果较好;(4)在一定范围内吸气强度越强其升力越高;(5)间歇式吸气也可提高平均升力,但引起升力的波动。

Modeling of mass transfer characteristics of bubble column reactor with surfactant present

Danckwert’s method was used to determine the specific interfacial area, a, and the individual mass transfer coefficient, kL, during absorption of CO2 in a bubble column with an anionic surfactant in the carbonate-bicarbonate buffer solution and NaAsO2 as catalyst, the presence of which decreases the specific interfacial area and the individual mass transfer coefficient. The specific interfacial area and the individual mass transfer coefficient increase with increasing su- perficial gas velocity. The specific interfacial area decreases whereas the individual mass transfer coefficient increases with increasing temperature. The results of experiments were used to determine the dependence of a, kL, and kLa on the surface tension, the temperature of the absorption phase, and the superficial velocity of the gas. The calculated results from the correlation were found to be within 10% deviation from the actual experimental results.

A numerical investigation in buoyancy effects on micro jet diffusion flame

The buoyancy effect on micro hydrogen jet flames in still air was numerially studied.The results show that when the jet velocity is relatively large(V≥0.2 m/s),the flame height,width and temperature decrease,whereas the peak OH mass fraction increases significantly under normal gravity(g=9.8 m/s^2).For a very low jet velocity(e.g.,V=0.1 m/s),both the peak OH mass fraction and flame temperature under g=9.8 m/s^2 are lower than the counterparts under g=0 m/s^2.Analysis reveals that when V≥0.2 m/s,fuel/air mixing will be promoted and combustion will be intensified due to radial flow caused by the buoyancy effect.However,the flame temperature will be slightly decreased owing to the large amount of entrainment of cold air into the reaction zone.For V=0.1 m/s,since the heat release rate is very low,the entrainment of cold air and fuel leakage from the rim of tube exit lead to a significant drop of flame temperature.Meanwhile,the heat loss rate from fuel to inner tube wall is larger under g=9.8 m/s^2 compared to that under g=0 m/s^2.Therefore,the buoyancy effect is overall negative at very low jet velocities.

Influence of Water Vapor on Silica Membrane： Adsorption Properties and Percolation Effect

The influence of water vapor on silica membrane with pore size of ,-4A has been investigated in terms of adsorption properties and percolation effect at 50 and 90 ℃. Two methods are employed： spectroscopic ellipsometry for water vapor adsorption and gas permeation of binary mixture of helium and H2O The adsorption behaviors on the silica membrane comply with the first-order Langmuir isotherm. The investigation demonstrates that helium flux through the silica membrane decreases dramatically in presence of H20 molecules. The transport of gas molecules through such small pores is believed not to be continuous any more, whereas it is reasonably assumed that the gas molecules hop from one occupied site to another unoccupied one under the potential gradient. When the coverage of H20 molecules on the silica surface increases, the dramatic decrease of helium flux could be related to percolation effect, where the adsorbed H20 molecules on the silica surface block the hopping of helium molecules.

恶劣海况下的船舶电力推进系统控制策略仿真

针对恶劣海况下电力推进系统常规控制策略适应性不足的问题,提出抗过旋控制策略.首先,分析恶劣海况下螺旋桨出入水现象对螺旋桨产生的推力和转矩的影响,提出恶劣海况下带动态限速模块的抗过旋控制策略(抗过旋控制策略#1)和带吸气(ventilation)识别模块的抗过旋控制策略(抗过旋控制策略#2),并在后者中设计三种吸气效应识别器来侦测吸气效应;然后,在Matlab/Simulink环境中搭建船舶电力推进控制系统仿真模型;最后,设计恶劣海况下的仿真实验,比较常规控制策略与抗过旋控制策略之间的性能优劣.仿真实验结果表明,在恶劣海况下,带吸气识别模块的抗过旋控制策略拥有优良的控制性能.

Effects of bleed hole size on supersonic boundary layer bleed mass flow rate

The bleed hole diameter,depth,and boundary layer thickness are key design parameters of a supersonic bleed system.The evolution trend of single-hole bleed flow coefficient with the ratio of boundary layer thickness to bleed hole diameter and the ratio of bleed hole depth to diameter is investigated by numerical simulations under choking and non-choking conditions.The results show that the subsonic leading edge of the circular hole and the subsonic part of the boundary layer are the main factors causing lateral flow of the bleed hole.The effect of diameter on bleed mass flow rate is due to the viscous effect which reduces the effective diameter.The larger the ratio of displacement thickness to bleed hole diameter,the more obvious the viscous effect is.The depth affects bleed flow rate by changing the opening and closing states of the separation zone.When a certain depth is reached,the development of the boundary layer reduces the effective captured stream tube and thus reduces the bleed mass flow rate.The main objective of the study is to obtain the physical mechanism of the bleed hole size parameters affecting the bleed mass flow rate,and to provide theoretical guidance for the selection of the size of bleed holes in the design of a porous arrays bleed system in hypersonic inlets.