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The calculation of the normal stresses from the flow curve is considered on the basis of the method of correlation of the frequency and stationary characteristics of flowing polymer systems.


Serviceability characteristics of flowing repairs to propped and unpropped bridge structures


Due to the signal characteristics of flowing blood, inherent contrast between blood pool and myocardium is achieved without the use of contrast media.


The microcontroller timer developed for the purpose is used to obtain experimental data on time characteristics of flowing (moving) melt.


The physical, chemical and biological characteristics of flowing and standing water habitats will be studied.

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 The characteristics of flow in cooling reservoirs, due to the presence of thermal stratification and the heat exchange on the surface, is far more complicated than that of flow usually encountered in hydraulic engineering. The criteria for similarity of flow in models and prototypes are so numerous that the satisfication of all of them is not practical. The author presented, in 1959, the criteria for similarity with due consideration of the fact that on one hand, they should be sufficient for... The characteristics of flow in cooling reservoirs, due to the presence of thermal stratification and the heat exchange on the surface, is far more complicated than that of flow usually encountered in hydraulic engineering. The criteria for similarity of flow in models and prototypes are so numerous that the satisfication of all of them is not practical. The author presented, in 1959, the criteria for similarity with due consideration of the fact that on one hand, they should be sufficient for the reproduction of main hydraulic and thermal characteristics in models; and on the other hand, it should be practical to satisfy the criteria in ordinary hydraulic laboratories. The similarity laws thus obtained are presented in equation (17). When the room temperature and moisture content can be controlled and adjusted the similarity laws as shown in eq. (13) are recommended. A series of verification tests and field observations were carried out in the following years, the latter being made in two cooling reservoirs. In one of the reservoirs, which has an average water depth of 4.5m and a surface area of 5 km~2, general flow pattern of the surface layer and of the bottom layer of the thermal density current was observed. They were well verified in a model with length scale L_r=250 and depth scale Z_r=40. The other cooling reservoir is a much smaller one, with surface area of only 9000 m~2 and an average water depth of 2.5m. Besides flow characteristics, the variation of the temperature field of the reservoir and of the total heat balance with respect to time were carefully measured. A model with L_r=15 and Z_r=6 served to verify the hydraulic and thermodynamic data obtained in the field. The paper is a collective report, including the derivation of the similarity law and its verifications, and a discussion of the scale effects.  冷却池中的水流运动,由于存在着水流本身的溫差作用及池面的散热受热作用,其运动規律,要較一般水流运动規律复杂得多;其模型相似条件,亦极难全面滿足,本文从整个水池的基本相似要求出发,着重考虑了水面溫度場相似的要求,提出了模型律;对存在着的比尺矛盾作了一些探討,并在室內和現場作了一些試驗驗証。几年来的試驗实践說明,虽然目前的模型相似問題,还有不少环节沒有解决,直接用热水作为試驗介貭的模型試驗,不失为規划冷却池工程布置和估計水面散热能力的一种有效工具。  By adopting the critical depth ye and critical slope σ as the parameters for flow depth and bottom slope respectively,this paper presents the unified nondimensional computation method for 15 types of flow profiles in trapezoidal open channels with five classes of bottom slopes.Some new ideas for the characteristics of flow profiles have been explored by examples of computation and plotting of the generalized nondimensional φ(u) function.Furthermore, this paper indicates that it is improper... By adopting the critical depth ye and critical slope σ as the parameters for flow depth and bottom slope respectively,this paper presents the unified nondimensional computation method for 15 types of flow profiles in trapezoidal open channels with five classes of bottom slopes.Some new ideas for the characteristics of flow profiles have been explored by examples of computation and plotting of the generalized nondimensional φ(u) function.Furthermore, this paper indicates that it is improper to use symbols σe and σo to represent the critical slope corresponding to the critical depth ye and normal depth y0 respectively,since if the discharge Q is a given value, σe and σo must be identical. Usually, the hydraulic exponent for trapezoidal open channel is suitable to be represented by n and m, or it is not reasonable to use a single value n, besides the exception of shallow wide rectangular section.  本文采用临界水深y_c及临界坡降σ分别作为水深及底坡的参数,对五类坡底的梯形渠道内15种水面线,提出了统一的无尺度计算方法.通过对微分函数式的计算及作图举例,进一步阐明了水面线的一些特性. 文中还指明,在流量为给定值的条件下,相应于临界水深y_c的σ_c和相应于正常水深y_0的σ_0必然相等,而且从σ的定义就不应给以不同的符号.除了浅宽矩形断面的特例外,水力指数不是单一的n值而应区别为n及m二值.  In this paper, the early stages of unsteady flow around a circular cylinder, started impulsively from rest and subsequently moving with a constant velocity perpendicular to its axis, are studied by coupling discrete vortex potential flow theory with boundary layer theory. The flow is considered to be laminar and the Reynolds number in high. development in time of vortex motion, characteristics of flow field, boundary layer separation point and drag coefficient are given in detail. Results... In this paper, the early stages of unsteady flow around a circular cylinder, started impulsively from rest and subsequently moving with a constant velocity perpendicular to its axis, are studied by coupling discrete vortex potential flow theory with boundary layer theory. The flow is considered to be laminar and the Reynolds number in high. development in time of vortex motion, characteristics of flow field, boundary layer separation point and drag coefficient are given in detail. Results of coupled calculation contain the interactions between boundary layer, external potential flow field and near wake. The calculated development of symmetric vortex posseses many of the observed features in flow field visualization. Pressure and velocity distributions are also given. The drag coefficient obtained is in excellent agreement with experiment. In the calculation of boundary layer separation point, the Startford method is applied to the quasisteady boundary layer state. The calculated result is better than those given by others and the computation is simpler. Shedding times and locations of discrete vortices, which have been generated before the boundary layer reaehs the qusisteady state, are determined according to the unsteady M. R. S. criterion. The effect of these initial discrete vortices on the main vortex development and flow field is also discussed.  本文用离散涡位流理论与边界层理论相结合的方法,研究高雷诺数、不可压、层流情况下圆柱非定常运动的初期流动(圆柱由静止突然起动而后保持匀速运动),给出了柱后旋涡发展的详细过程;流场分布、边界层分离点及阻力等随时间的变化规律。本文耦合计算结果包含了流动过程中边界层、外流与近尾迹三者的相互作用。计算所得的旋涡发展与实验显示的图象十分相似,物面压力与速度分布合理,阻力计算与实验结果相符很好。在分离点耦合计算中将stratford方法应用到准定常边界层情况,计算方法简单结果也较满意。对于准定常变化前分离产生的离散涡,其脱落时间和初始位置,本文根据非定常M. R. S. 分离准则确定。文中还讨论了这些离散涡对柱后旋涡发展及流动的影响。   << 更多相关文摘 
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