柔性微热剪切应力传感器阵列

设计了一种基于微机电系统的、制备在柔性聚酰亚胺衬底上的双热线结构微型热剪切应力传感器阵列,可用于复杂形状物体表面所受剪切应力的矢量化测量.基于传感器的原理,用Comsol软件对传感器进行了温度场和流场的仿真,说明了传感器制作工艺流程,用硅橡胶与聚酰亚胺在酒精中浸泡后易于剥离的特点实现柔性传感器脱膜.对传感器实物进行了温度电阻系数和响应频率的测试.实验结果表明,设计的工艺路线简单,结构参数合理,可以实现所需柔性传感器阵列.

基于聚酰亚胺基底的热线式剪切应力传感器

利用非硅微机械加工技术,制作了一种柔性热线式剪切应力微传感器。该传感器以聚酰亚胺膜为基底,可与被测曲面物体紧密贴合,具有较好的测量适应性和准确性。传感器采用线性度好、温度系数较高的铂金属制作敏感热线。为减少对被测流场的干扰且便于传感器的信号传输,传感器使用了背面引线结构。设计了恒温工作模式的传感器检测电路,并对电路的工作原理和参数设置进行了详细分析。对传感器进行了风洞实验,绘制得到剪切应力与输出电压的关系曲线。实验结果表明,设计制作的传感器及其电路可行。

Heat transfer intensification in hydromagnetic and radiative 3D unsteady flow regimes: A comparative theoretical investigation for aluminum and γ-aluminum oxides nanoparticles

This article investigates the colloidal study for water and ethylene glycol based nanofluids.The effects of Lorentz forces and thermal radiation are considered.The process of non-dimensionalities of governing equations is carried out successfully by means of similarity variables.Then,the resultant nonlinear nature of flow model is treated numerically via Runge-Kutta scheme.The characteristics of various pertinent flow parameters on the velocity,temperature,streamlines and isotherms are discussed graphically.It is inspected that the Lorentz forces favors the rotational velocity and rotational parameter opposes it.Intensification in the nanofluids temperature is observed for volumetric fraction and thermal radiation parameter and dominating trend is noted for γ-aluminum nanofluid.Furthermore,for higher rotational parameter,reverse flow is investigated.To provoke the validity of the present work,comparison between current and literature results is presented which shows an excellent agreement.It is examined that rotation favors the velocity of the fluid and more radiative fluid enhances the fluid temperature.Moreover,it is inspected that upturns in volumetric fraction improves the thermal and electrical conductivities.

HEAT AND MASS TRANSFER EFFECTS ON CARREAU FLUID MODEL FOR BLOOD FLOW THROUGH A TAPERED ARTERY WITH A STENOSIS

In the current critique, we deliberate the blood flow through narrowing vein with a steno- sis in the manifestation of heat and mass transmission. The non-Newtonian flora of blood in small veins are examined mathematically by demonstrating the blood as Carreau fluid. The illustration for the blood flow is debated through an axially irregular but outward regular stenosis. Regularity in the dissemination of the fortification clipping stress and resistive impedance and their evolution with the emerging stenosis is a new significant feature of our investigation. Analytical solutions have been appraised for ＂velocity, tem- perature, concentration, resistance impedance, wall shear stress and shearing stress at the stenosis throat＂. The graphical consequences of different types of tapering arteries （i.e. ＂converging tapering, diverging tapering, non-tapered artery＂） have been studied for dissimilar constraints of attention. Rivulet shapes have been strategized for different parameters at the culmination of the article.

Signatures of shear thinning-thickening transition in steady shear flows of dense non-Brownian yield stress systems

Steady shear flows of dense athermal systems composed of soft disks are investigated via non-equilibrium molecular dynamics simulations, from which we sort out links among the structure, dynamics, and shear rheology. The systems at rest are jammed packings of frictionless disks with a nonzero yield stress. Driven by low shear rates, the flows shear thin due to the presence of the nonzero yield stress, but transit to shear thickening above a crossover shear rate γc - At γc, we observe the strongest struc- tural anisotropy in the pair distribution function, which serves as the structural signature of the shear thinning-thickening tran- sition. We also observe dynamical signatures associated with the transition： At γc , scaling behaviors of both the mean squared displacement and relaxation time undergo apparent changes. By performing a simple energy analysis, we reveal an underlying condition for the shear thickening to occur： d（lnTg）/d（Inγ） 〉 2 with Tg the kinetic temperature. This condition is confirmed by simulations.