A Detailed Analysis of Guard-Heated Wall Shear Stress Sensors for Turbulent Flows

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dc.contributor.authorAle Etrati Khosroshahi, Seyed Ali
dc.contributor.supervisorBhiladvala, Rustom
dc.date.accessioned2013-07-30T18:43:56Z
dc.date.available2013-07-30T18:43:56Z
dc.date.copyright2013en_US
dc.date.issued2013-07-30
dc.degree.departmentDept. of Mechanical Engineeringen_US
dc.degree.levelMaster of Applied Science M.A.Sc.en_US
dc.description.abstractThis thesis presents a detailed, two-dimensional analysis of the performance of multi-element guard-heated hot-film wall shear stress microsensors for turbulent flows. Previous studies of conventional, single-element sensors show that a significant portion of heat generated in the hot-film travels through the substrate before reaching the fluid, causing spectral and phase errors in the wall shear stress signal and drastically reducing the spatial resolution of the sensor. Earlier attempts to reduce these errors have focused on reducing the effective thermal conductivity of the substrate. New guard-heated microsensor designs proposed to overcome the severe deficiencies of the conventional design are investigated in this thesis. Guard-heaters remove the errors associated with substrate heat conduction, by forcing zero temperature gradient at the edges and bottom face of the hot-film, and hence, block the indirect heat transfer to the flow. Air and water flow over the sensors are studied numerically to investigate design, performance and signal strength of the guard-heated sensors. Our results show, particularly for measurements in low-conductivity fluids such as air, that edge guard-heating needs to be supplemented by a sub-surface guard-heater, to make substrate conduction errors negligible. With this two-plane guard-heating, a strong non-linearity in the standard single-element designs can be corrected, and spectral and phase errors arising from substrate conduction can be eliminated.en_US
dc.description.proquestcode0548en_US
dc.description.proquestemailetrati@uvic.caen_US
dc.description.scholarlevelGraduateen_US
dc.identifier.urihttp://hdl.handle.net/1828/4713
dc.languageEnglisheng
dc.language.isoenen_US
dc.rights.tempAvailable to the World Wide Weben_US
dc.subjectGuard-heatingen_US
dc.subjectWall shear stressen_US
dc.subjectThermal sensoren_US
dc.subjectTurbulent flowen_US
dc.subjectWall turbulenceen_US
dc.subjectConjugate heat transferen_US
dc.subjectConstant temperature anemometryen_US
dc.subjectHot-filmen_US
dc.subjectFrequency responseen_US
dc.subjectSubstrate heat conductionen_US
dc.subjectCTAen_US
dc.titleA Detailed Analysis of Guard-Heated Wall Shear Stress Sensors for Turbulent Flowsen_US
dc.typeThesisen_US

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