Hardalupas, Y.

Soulopoulos, N.

Stetsyuk, V.

Taylor, A.M.K.P.

English

University of Huddersfield Repository

University of Huddersfield RepositoryStetsyuk, V., Soulopoulos, N., Hardalupas, Y. and Taylor, A.M.K.P.Thermal dissipation rate measurements in swirl-stabilised flamesOriginal CitationStetsyuk, V., Soulopoulos, N., Hardalupas, Y. and Taylor, A.M.K.P. (2014) Thermal dissipation rate measurements in swirl-stabilised flames. In: Combustion Research and Applications – State of the Art, 24th September 2014, Imperial College London, Engineering Department. This version is available at http://eprints.hud.ac.uk/27903/The University Repository is a digital collection of the research output of theUniversity, available on Open Access. Copyright and Moral Rights for the itemson this site are retained by the individual author and/or other copyright owners.Users may access full items free of charge; copies of full text items generallycan be reproduced, displayed or performed and given to third parties in anyformat or medium for personal research or study, educational or not-for-profitpurposes without prior permission or charge, provided:• The authors, title and full bibliographic details is credited in any copy;• A hyperlink and/or URL is included for the original metadata page; and• The content is not changed in any way.For more information, including our policy and submission procedure, pleasecontact the Repository Team at: E.mailbox@hud.ac.uk.http://eprints.hud.ac.uk/Combustion Research and Applications – State of  the Art1. INTRODUCTIONThermal dissipation rate measurements in swirl-stabilised flamesV. Stetsyuk, N. Soulopoulos, Y. Hardalupas and A.M.K.P. TaylorDepartment of  Mechanical Engineering,Imperial College London, South Kensington Campus, London SW7 2AZ3. EXPERIMENTAL SETUPA central fuel nozzle is surrounded by a concentric swirling air flow. The “fuel” used was a mixture with volumetric composition of  22.1%CH4, 33.2%H2, 44.7%N2 (stoichiometric mixture fraction is 0.167). The combination of  this fuel and the air yields a Rayleigh scattering  cross section, which is constant within ±3% across the flame. Scale factor was 0.025 (mm/pixel), while the actual spatial resolution, quantified by the modulation transfer function (MTF), was 0.3(mm) at 50% MTF. The Kolmogorov scale was circa 0.15 mm. The swirl number of  swirling co-flow was in the range of  0.3-1.07. The Reynolds number of  swirling and jet fuel flow are 28662 and 3770 respectively.  Rayleigh scattering optical diagnostic technique was used to measure temperature distribution, which then was converted into thermal dissipation rate after appropriate denosing.4. RESULTS5. CONCLUSIONS2. AIMS AND OBJECTIVES• measurements of  thermal dissipation rate in turbulent non-premixed, reacting swirling jetsThe scalar dissipation rate                  (z mixture fraction, D is diffusivity) requires modeling in essentially all models for non-premixed combustion. Peters (1983) identified the scalar dissipation rate as a characteristic diffusion time scale, imposed by the mixing field. Direct measurements of  scalar dissipation rate in flames are extremely difficult. If  the temperature is assumed to be a function of  mixture fraction T=f(z) and by assuming Le=1, the relationship between the scalar dissipation and the thermal dissipation rate is according to*                      where                      is thermal dissipation rate.D z z   Imperial College London, Engineering Department, 24 September 2014 THE COMBUSTION INSTITUTE (British Section) 2T T T    /T dT dz  *D.A. Everest, J.F. Driscoll, W.J.A. Dahm, D.A. Feikema. Combustion and Flame 101 (1995) 58-68.3. RESULTSA photograph of  the flame as a function of  swirl number. From left to right S=1.07, 0.58 and 0.3.Instantaneous (left) and mean (right) temperature distribution for S=0.58 at y/Df=10, 7, 5, 3, 1 ( from top to bottom)./ 1fy D a) Raw temperature obtained from the measurements;b) Denoised temperaturec) Logarithm of  base 10 of  raw thermal dissipation (without filtering) d) Logarithm of  base 10 of  denoised thermal dissipation rate• The flame was stably attached to the fuel nozzle for all S.• Higher downstream mean temperatures for higher S.• P.d.f. of  temperature fluctuations is dependent on S.• Lower temperature fluctuations for higher downstream distances

Thermal dissipation rate measurements in swirl-stabilised flames

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