High temperature heat flux measurements

Hager, J. M.; Onishi, S.; Langley, Lawrence W.; Diller, Thomas E.

doi:10.2514/6.1991-165

Cited by 7 publications

(3 citation statements)

References 2 publications

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“…A different approach has recently been demonstrated by Hager et al (1993) in high-speed flows. The Heat Flux Microsensor (HFM) consists of a thin thermal resistance layer sandwiched between temperature sensors, as illustrated in Fig.…”

Section: Literature Reviewmentioning

confidence: 99%

Effects of Shock Wave Passage on Heat Transfer in a Transonic Turbine Cascade

Holmberg

Reid

Kiss

et al. 1994

Volume 4: Heat Transfer; Electric Power; Industrial and Cogeneration

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Results from a new facility for measuring heat transfer in transonic turbine cascades are repotted. An air heater has been built into the blow-down wind tunnel to heat the main flow for a 20 second run time. This allows control of the direction and magnitude of the heat transfer into the blade throughout the tests. A Heat Flux Microsensor was inserted into the blade to measure simultaneous surface heat flux and temperature. Measurements were made on the suction surface of the blades toward the trailing edge. Because of the long run times (20 s), the adiabatic wall temperature could be determined directly from the measured surface temperature and heat flux. Simultaneous pressure measurements were made with a Kulite transducer at the same distance from the leading edge to document shock passage. A separate shock tube was used to generate a shock wave which was introduced into the test section in front of the cascade. This shock was carried over the blade by the main flow. The resulting changes in heat flux correlated strongly with the unsteady pressure changes. An overall increase of 1.5 W/cm2 in heat flux was recorded for a pressure increase of 7 kPa during the initial passage of the shock.

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Section: Literature Reviewmentioning

confidence: 99%

Effects of Shock Wave Passage on Heat Transfer in a Transonic Turbine Cascade

Holmberg

Reid

Kiss

et al. 1994

Volume 4: Heat Transfer; Electric Power; Industrial and Cogeneration

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“…Although, this may be regarded as a limitation, advantages can be drawn from this fact by simply taking into account that, in principle, sensors can be calibrated with any heat source of known intensity, either convective or 'radiative'. As the various hypersonic effects illustrated before make it extremely difficult to establish a convective heat flux of known intensity transferred to a transducer, historically methods where calibration has been achieved by coating a sensor with a material with known absorptivity and exposing the instrument to a radiant heat flux of known intensity have enjoyed a widespread use (Barber [6]; Diller [7]; Hager et al [8]). Some relevant information along these lines (not necessarily connected with the hypersonic regime) has been collected by NIST (National Institute of Standards and Technology) for years (Murthy et al [9]).…”

Section: Introductionmentioning

confidence: 99%

A Mixed Radiative-Convective Technique for the Calibration of Heat Flux Sensors in Hypersonic Flow

Espósito¹,

Lappa²,

Pagliara³

et al. 2022

Fluid Dynamics &Amp; Materials Processing

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The ability to measure the very high heat fluxes that typically occur during the hypersonic re-entry phase of space vehicles is generally considered a subject of great importance in the aerospace field. Most of the sensors used for these measurements need to be checked periodically and re-calibrated accordingly. Another bottleneck relates to the need to procure thermal sources that are able to generate reliable reference heat fluxes in the range between 100 and 1000 kW/m 2 (as order of magnitude). In the present study, a method is presented by which, starting from a calibration system with a capacity of approximately 500 kW/m 2 only, heat fluxes in the range of interest for hypersonic applications are generated. The related procedure takes advantage of established standards for the characterization of a radiative heat flux. It also builds on the hybrid radiative-convective nature of typical hypersonic heat fluxes and the yet poorly explored possibility to use convective sources of heat to produce high-intensity fluxes. The reliability of such a strategy has been tested using a high enthalpy supersonic flow facility relying on an electric arc-heater and pure Nitrogen as work gas. Stagnation-point heat fluxes have been successfully measured (with reasonable accuracy) in the range between 600 and 1500 kW/m 2 for values of the centerline enthalpy spanning the interval from to 6 to 24 MJ/kg.

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“…A high temperature thermopile style gage called a heat flux micro-sensor (HFM) was developed and used in high temperature applications [12] as well as fire [13]. However, this gage is only rated for limited use to about 500 °C.…”

Section: Introductionmentioning

confidence: 99%

Quantifying Thermal Boundary Condition Details Using a Hybrid Heat Flux Gage

Lattimer¹,

Diller²

2011

Fire Safety Science - Proceedings of the 10th International Sym

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New methods and experimental techniques were developed in this research to quantify the incident heat flux, absorbed (net) heat flux into a sample, and heat transfer coefficient for samples exposed to mixed mode (radiation and convection) heat transfer typical in fires. Net heat flux into the material was measured at elevated temperatures using a recently developed hybrid heat flux gage, which is both a thermopile type gage as well as a slug calorimeter with an operating temperature >1000 ºC without cooling. The heat transfer coefficient was determined as a function of time using the hybrid gage output only through a reference state approach. The net heat flux and heat transfer coefficient were then used to calculate a cold surface heat flux and the adiabatic surface temperature. Experiments were performed in the cone calorimeter at different heat fluxes to quantify the incident heat flux, net heat flux, heat transfer coefficient, cold surface heat flux, and adiabatic surface temperature as a function of time. Measured heat transfer coefficients were 9-18 % different than values calculated using idealized natural convection correlations. The cold surface heat fluxes determined with the hybrid gage were within 5 % of cold surface heat fluxes measured using a water-cooled Schmidt-Boelter heat flux gage.KEYWORDS: heat flux, heat transfer coefficient, adiabatic surface temperature, cone calorimeter, high temperature heat flux gage, hybrid gage. NOMENCLATURE LISTINGA s area of exposed surface (m 2 ) β thermal expansion coefficient (

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High temperature heat flux measurements

Cited by 7 publications

References 2 publications

Effects of Shock Wave Passage on Heat Transfer in a Transonic Turbine Cascade

Effects of Shock Wave Passage on Heat Transfer in a Transonic Turbine Cascade

A Mixed Radiative-Convective Technique for the Calibration of Heat Flux Sensors in Hypersonic Flow

Quantifying Thermal Boundary Condition Details Using a Hybrid Heat Flux Gage

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