Local measurement of loss using heated thin film sensors

Mark R.D. Davies, Francis K. O'Donnell

Research output: Contribution to journalConference articlepeer-review

Abstract

A calibration equation is derived linking the non-dimensional entropy generation rate per unit area with the non-dimensional aerodynamic wall shear stress and free stream pressure gradient. It is proposed that the latter quantities, which can be measured from surface gauges, be used to measure the profile entropy generation rate. It is shown that the equation is accurate for a wide range of well-defined laminar profiles. To measure the dimensional entropy generation rate per unit area requires measurement of the thickness of the boundary layer. A general profile equation is given and used to show the range of accuracy of a further simplification to the calibration. For flows with low free stream pressure gradients, the entropy generation rate is very simply related to the wall shear stress, if both are expressed without units. An array of heated thin film sensors is calibrated for the measurement of wall shear stress, thus demonstrating the feasibility of using them to measure profile entropy generation rate.

Original languageEnglish
JournalAmerican Society of Mechanical Engineers (Paper)
Issue numberGT
Publication statusPublished - 1998
EventProceedings of the 1998 International Gas Turbine & Aeroengine Congress & Exhibition - Stockholm, Sweden
Duration: 2 Jun 19985 Jun 1998

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