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梁国光 《西安交通大学学报(医学版)》1997,(4)
森流体的经验公式为:其表观粘度ηa为该式中的卡森屈服值(τc)和卡森粘度(ηc),在一定切变率(γ)范围内,是不随γ而变化的常数。因此,ηa随γ增大而下降的原因只能用的关系来解释。这种反比关系必须在τc≠±的条件下才成立。否则,卡森流体变为牛顿流体。卡森粘度属动力性粘度。在圆形管道中,其存在于栓流与管壁之间,相对滑动的液层内。血液卡森粘度与血细胞压积,红细胞刚性及血浆粘度有关。并随上述因素的增大而增大。血液卡森屈服值与血沉无正相关性,其原因有待进一步研究。笔者建议,用卡森屈服值和卡森粘度作为定量描述卡森流体流变特性的客观指标。 相似文献
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采用流变学理论对砼在输送管内的流速及流动阻力进行了公式推导和可泵性分析,并根据泵送砼的工作性要求,设计出合理的砼配合比,以充分发挥泵送砼能加快施工进度,提高工程质量的效果. 相似文献
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对无流化剂大流动性砂浆内部晶体结构影响试件强度作了部分分析 ,通过试验结果验证得出大流动性砂浆内部水化结晶过程中 ,由于晶体结构的破坏而出现粘性变化 ,同时表现为砂浆短期抗压强度的相应改变 相似文献
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大庆油田稠油流变特性的分析 总被引:1,自引:0,他引:1
对大庆油田稠油开展流变特性实验研究,在一定温度范围内作出其黏温曲线和流变曲线,对实验结果进行归纳分析,确定稠油的流体类型以及牛顿流与非牛顿流的转变点,总结出稠油流变规律,为实际生产提供了一种有效的理论依据。 相似文献
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布敦岩沥青改性沥青胶浆高温动态流变性能的试验研究 总被引:3,自引:0,他引:3
为了评价不同掺量的布敦岩沥青对基质沥青的改性效果,采用先进的动态剪切流变仪Advanced Rheometer(AR)对岩沥青改性沥青胶浆的高温动态流变性能进行了试验研究,主要评价指标有相位角、储能模量、车辙因子和动粘度等。研究发现岩沥青改性沥青胶浆的高温性能明显优于基质沥青;车辙因子和动粘度指标显示岩沥青改性沥青胶浆具有与SBS改性沥青胶浆相当的抗车辙性能,但是,其温度敏感性高于SBS改性沥青胶浆;岩沥青掺量对胶浆性能影响较明显,岩沥青与基质沥青质量比达到1∶1时,沥青胶浆的高温性能已经得到明显改善,可以满足路面使用性能要求。 相似文献
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A self-tuning fuzzy PID (ST-FPID) control scheme is implemented within a joint interactive (Matlab/Simulink/Fluent) co-simulation framework for effective two degrees of freedom (2DOF) vortex-induced vibration (VIV) control of an elastically-mounted circular cylinder in laminar cross-flow of incompressible non-Newtonian power-law fluids based on the control action of a single transverse force actuator. The model-free controller, which systematically tunes the control parameters online in real time based on given rules, is well-known to be highly advantageous over the previously employed conventional PID controllers. It is particularly capable of handling the intricate non-linear dynamic effects inherent in the complex fluid rheology of non-Newtonian flow past the cylinder in presence of unmodeled system dynamics, high parametric uncertainties, diverse operational conditions, and time-varying external disturbances and control signals. Extensive numerical simulations reveal that the complex shear-thinning and shear-thickening behaviors of fluid viscosity can substantially influence the cylinder dynamic response, applied hydrodynamic forces, and flow structure. In particular, effectiveness and high performance of the adopted ST-FPID control strategy in substantial suppression of the high amplitude coupled 2DOF VIV of the elastically-mounted cylinder at selected critical reduced velocities in the lock-in region are established for a wide range of power-law index parameters (e.g., up to 83% reduction in RMS value of cylinder cross-flow displacement and up to 35% reduction in RMS value of cylinder in-line displacement for n=1and U* = 5 at Re = 100). Also, the vigorous action of the error-driven ST-FPID controller in forcing the high strength vortex shedding patterns of the uncontrolled cylinder out of the lock-in condition into the classical von Kármán vortex street of 2S-type mode of moderately weaker strengths is verified. 相似文献