test_moissonnage_selune
type: Agent

Development of novel diagnostic techniques to measure heat release rate perturbations in flames
type: Dataset
contact point: Organization
  fn: CCSD
keyword: ultrasonic-waves
keyword: laser-interferometric-vibrometry
keyword: flamme-premelangee
keyword: theses
keyword: ondes-ultrasonores
keyword: premixed-flames
keyword: interferometrie-laser-doppler
keyword: spiotherengineering-sciences-physicsother
keyword: infoeu-reposemanticsdoctoralthesis
landing page: https://theses.hal.science/tel-00997413
description: Heat release rate disturbances are the sources of additional thermal stresses, direct and indirect combustion noise and undesirable vibrations. In extreme cases, these perturbations may even cause destructive combustion instabilities. These quantities are difficult to measure in practical burners. The objective of this work is to develop two alternative diagnostics to measure heat release rate fluctuations in unsteady flames. These techniques are validated in generic configurations for perfectly premixed laminar flames. The first method is an acoustic technique, which is based on the measurement of the travel time of ultrasonic waves through the flames. Fluctuations of the sound propagation time transmission through unsteady flames are used to estimate perturbations in the burned gases width along the acoustic path. This information is then used to reconstruct heat release rate fluctuations. This technique is validated in the cases of unstable laminar premixed flames driven by buoyancy forces and for flames submitted to harmonic flow velocity modulations. Analytical expressions are derived linking fluctuations in heat release rate and disturbances of the sound travel time. Measurements made with this acoustic technique are compared with optical detections based on the flame chemiluminescence and with predictions from an analytical model. Good agreements are obtained between these different methods validating the proposed technique. The second method envisaged is an optical technique based on a Laser Interferometric Vibrometer used to measure integrated density perturbations along the optical path of a laser beam. It is shown that density disturbances along this path result mainly from heat release rate fluctuations when the flames are confined. A link is established to reconstruct heat release rate disturbances from the signal of the interferometer. The technique is validated in the case of pulsated laminar premixed flames. Measurements are compared to line-of-sight…
identifier: NNT: 2012ECAP0012
issued: 2026-05-05T10:04:31.704889
language: en
modified: 2026-05-05T10:04:31.704894

Development of novel diagnostic techniques to measure heat release rate perturbations in flames
type: Distribution
access URL: https://theses.hal.science/tel-00997413
format: HTML
issued: 2026-05-05T10:04:31.709549
modified: 2026-05-05T10:04:31.694173