The temperature of a heated foil, exposed to a turbulent flow, changes continuously in time due to the fluctuation of the convective heat transfer coefficient. Measuring with enough temporal resolution the foil temperature map and solving the unsteady energy balance of the foil can allow restoring the instantaneous value of the convective heat transfer coefficient. Nevertheless, the high characteristic frequencies of turbulent flows (especially in air) result in very small temperature fluctuations, which are typically hard to measure with an infrared camera. This work presents a novel filtering approach based on Proper Orthogonal Decomposition which allows to dramatically reduce the measurement random noise, thus enabling the detection of small temperature fluctuations and, as a consequence, to improve the estimate of instantaneous distributions of the convective heat transfer coefficient. The proposed methodology is tested on synthetic jets impinging on a foil, actuated with a loudspeaker at various actuation frequencies. The measurement capabilities of the present technique are assessed through comparison with measurements obtained from raw data and phase averaged measurements.

Towards enabling time-resolved measurements of turbulent convective heat transfer maps with IR thermography and a heated thin foil / Raiola, Marco; Greco, CARLO SALVATORE; Contino, Mattia; Discetti, Stefano; Ianiro, Andrea. - In: INTERNATIONAL JOURNAL OF HEAT AND MASS TRANSFER. - ISSN 0017-9310. - 108:(2017), pp. 199-209. [10.1016/j.ijheatmasstransfer.2016.12.002]

Towards enabling time-resolved measurements of turbulent convective heat transfer maps with IR thermography and a heated thin foil

GRECO, CARLO SALVATORE;CONTINO, MATTIA;
2017

Abstract

The temperature of a heated foil, exposed to a turbulent flow, changes continuously in time due to the fluctuation of the convective heat transfer coefficient. Measuring with enough temporal resolution the foil temperature map and solving the unsteady energy balance of the foil can allow restoring the instantaneous value of the convective heat transfer coefficient. Nevertheless, the high characteristic frequencies of turbulent flows (especially in air) result in very small temperature fluctuations, which are typically hard to measure with an infrared camera. This work presents a novel filtering approach based on Proper Orthogonal Decomposition which allows to dramatically reduce the measurement random noise, thus enabling the detection of small temperature fluctuations and, as a consequence, to improve the estimate of instantaneous distributions of the convective heat transfer coefficient. The proposed methodology is tested on synthetic jets impinging on a foil, actuated with a loudspeaker at various actuation frequencies. The measurement capabilities of the present technique are assessed through comparison with measurements obtained from raw data and phase averaged measurements.
2017
Towards enabling time-resolved measurements of turbulent convective heat transfer maps with IR thermography and a heated thin foil / Raiola, Marco; Greco, CARLO SALVATORE; Contino, Mattia; Discetti, Stefano; Ianiro, Andrea. - In: INTERNATIONAL JOURNAL OF HEAT AND MASS TRANSFER. - ISSN 0017-9310. - 108:(2017), pp. 199-209. [10.1016/j.ijheatmasstransfer.2016.12.002]
File in questo prodotto:
Non ci sono file associati a questo prodotto.

I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.

Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11588/661619
Citazioni
  • ???jsp.display-item.citation.pmc??? ND
  • Scopus 14
  • ???jsp.display-item.citation.isi??? 11
social impact