环形孔径白光散斑照相法的研究

提出利用环形孔径进行白光散斑照相，测量物体的变形和位移。该方法具有灵敏度高、灵敏度调节范围宽、全场滤波可得到物体所有方向的位移等值条纹和逐点滤波可提高衍射晕边缘的条纹对比度等特点。     

Improving the accuracy of the capacitance method for void fraction measurement

Void fraction measurements were made using capacitance method. Five capacitor configurations were manufactured and tested; parallel, strip-type plates, ring-type plates, unidirectional, and double-helix. The void fraction was simulated by nonflow air-paraffin wax, air-glass, air-wood, and air-Freon 113 systems. The relative statistical error in void fraction measurement was minimized by taking into account the spacing between the ends of the two electrodes.     

Interpretation of atomization rates of the liquid film in gas-liquid annular flow

For vertical gas-liquid annular flow the fraction of the liquid in the gas is controlled by the rate of atomization of the liquid film flowing along the wall and the rate of deposition of droplets entrained in the gas. Measurements of the rate of atomization are interpreted by a Kelvin-Helmholtz mechanism. Small wavelets on the liquid film are visualized to be entrained when wave-induced variations in the gas pressure cannot be counterbalanced by surface tension effects.     

弯扭静子叶片的环形叶栅试验

弯扭静子叶片的环形叶栅试验徐文远，于清，杨弘，王仲奇（哈尔滨工业大学动力工程系哈尔滨１５０００１）关键词：弯扭叶片，环形叶栅，试验随着弯扭叶片理论的发展，它在国内外叶轮机械中的应用日益广泛。在国外，弯扭叶片已应用于新一代航空发动机中，如Ｖ２５００、Ｐ...     

The effect of the scale factor on the focusing properties of a vortex gas flow

An experimental study is carried out to investigate a bilateral direct-flow vortex tube of small (0.3–3.0)·10⁻² m) size and to compare its optical properties with those characteristics of vortex tubes of a larger ((3–16)\10⁻² m) scale. A model is suggested for forming transverse profiles of the intensity of laser beams with an intensity hole in the center and of annular beams. Translated from Zhural Prikladnoi Spektroskopii, Vol. 64, No. 3, pp. 386–389, May–June, 1997     

Steady-state thermal stresses in an infinite elastic medium containing an annular crack

An axisymmetric steady-state thermoelastic problem of an infinite isotropic medium containing an annular crack is considered. The faces of the crack are exposed to prescribed temperature distribution. The normal components of stress and displacement on the crack plane and the stress-intensity factors at the boundaries of the crack are expressed in power series in terms of the ratio between the radii of the inner and outer boundaries. These are illustrated graphically.     

环状截面同轴金属波导的特性研究

以电磁场理论为出发点，对满足环状截面同轴金属波导边界条件的麦克斯韦方程组求解，得到了环状同轴波导管内的电磁场各分量方程，并以TE模灰例详尽分析了环状金属波导管中的模式特征、色散关系、光束传播及其强度分布特性。     

Steady thermocapillary-buoyant convection in a shallow annular pool. Part 2: Two immiscible fluids

This work is devoted to the study of steady thermocapillary-buoyant convection in a system of two horizontal superimposed immiscible liquid layers filling a lateral heated thin annular pool.The governing equations are solved using an asymptotic theory for the aspect ratios ε→ 0.Asymptotic solutions of the velocity and temperature fields are obtained in the core region away from the cylinder walls.In order to validate the asymptotic solutions,numerical simulations are also carried out and the results are compared to each other.It is found that the present asymptotic solutions are valid in most of the core region.And the applicability of the obtained asymptotic solutions decreases with the increase of the aspect ratio and the thickness ratio of the two layers.For a system of gallium arsenide (lower layer) and boron oxide (upper layer),the buoyancy slightly weakens the thermocapillary convection in the upper layer and strengthens it in the lower layer.     

Reflection and transmission of plane acoustic waves in an infinite annular duct with a finite gap on the inner wall

The diffraction of acoustic waves by an infinitely long annular duct having a finite gap on the inner wall is investigated rigorously. The related boundary‐value problem is formulated into a modified Wiener–Hopf equation, which is then reduced to a pair of simultaneous Fredholm integral equations of the second kind. At the end of the analysis, numerical results illustrating the effects of the width of the coaxial cylindrical waveguide and the gap length on the diffraction phenomenon are presented. Copyright © 2010 John Wiley & Sons, Ltd.     

具有双电子束结构的双波段相对论返波振荡器粒子模拟研究北大核心CSCD

研究了一种能够同时产生C波段和X波段微波、具有双电子束结构的相对论返波振荡器,采用嵌套式的高频结构将两个波段的束-波相互作用空间隔离开来,从而使两个波段的束-波相互过程互不影响。当二极管电压为650kV、内外环形电子束流分别为5.4,6.4kA、导引磁场为2.2T时,两个波段微波的频率分别为4.625,8.450GHz,模拟产生的微波功率分别为920,600MW,转换效率约为21.8%,17.1%。并采用粒子模拟法研究了导引磁场、二极管电压及两个束-波相互作用区关键结构参数对器件运行的影响,给出了双波段微波功率、频率随导引磁场、二极管电压等参数的变化曲线。