On the use of Irwin probes to measure wall shear stresse in rectangular ducts of constant section.

Author(s) : FARIA R., FERREIRA A. D., LOPES A. M. G., et al.

Summary

Non-circular ducts have been commonly used in engineering practice since early 20th century. However, the need for refined flow control aiming improved equipment effectiveness while maintaining or enhancing operating settings has led to a renewed interest by the scientific community to study for flow in non-circular ducts. Although there is a sizeable body of literature for this type of flow, it is apparent that many questions remain to be answered particularly in what concerns the flow structure and its interaction with the pressure distribution and pressure loss. In this work it is reported the influence of duct aspect ratio and Reynolds number on fully developed flow of an incompressible fluid. The duct, which is smooth-walled, has a movable top surface allowing rectangular cross-sections of aspect ratio from 1:1.03 to 1:4.00. Turbulent mean flow characteristics are reported for this aspect ratio range and for Reynolds number from 104 to 9×104. The experimental friction coefficient is plotted using three different characteristic length scales, namely hydraulic diameter (Dh), square root of the cross-section area ( ??) and laminar equivalent diameter (DL), with the aim of evaluating which one is the best suited to represent the data obtained in this particular study. The study also aims to assess the performance of in-house built Irwin probes. To this purpose is established the relation between the wall shear stress and the pressure difference given by the sensor. In addition, it is evaluated the influence of longitudinal and transversal placement of the sensors on the experimental results.

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Details

  • Original title: On the use of Irwin probes to measure wall shear stresse in rectangular ducts of constant section.
  • Record ID : 30018135
  • Languages: English
  • Source: CYTEF 2016. VIII Congreso Ibérico y VI Congreso Iberoamericano de las Ciencias y Técnicas del Frío, Coimbra-Portugal, 3-6 mayo, 2016.
  • Publication date: 2016/05/03

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