A rational correlation of combustion noise results from open turbulent premixed flames

Heat release rate correlation and combustion noise in premixed flames

“…Also, note that the fine details of heat release mechanisms and their physics in these different combustion modes may influence the characteristics of p , but (1.1) clearly notes that the integral value drives the pressure fluctuation and thus the direct noise only depends on the combustion mode through its influence on the rate of change of the total rate of heat released, as noted by Price et al (1968) and Strahle (1971). However, the following points can be noted from a number of studies on combustion noise emitted by premixed Strahle 1978;Strahle & Shivashankara 1975;Kilham & Kirmani 1979;Kotake & Takamoto 1987Rajaram & Lieuwen 2003;Hirsch et al 2007), non-premixed (Ohiwa, Tanaka & Yamaguchi 1993;Klein & Kok 1999;Singh, Frankel & Gore 2004;Flemming, Sadiki & Janicka 2007;Ihme, Pitsch & Bodony 2009) and partially premixed (Singh et al 2005;Duchaine, Zimmer & Schuller 2009) flames: (i) the combustion noise has a broadband spectrum with a peak sound level of about 60-80 dB in the frequency range of about 200-1000 Hz, (ii) the overall SPL increases with the fuel flow rate and the heating value of the fuel, (iii) there is a considerable increase in the SPL if one mixes air with the fuel (Singh et al 2005) so that the equivalence ratio stays beyond the rich flammability limit; however, this observed increase might be due to room resonance since the experiment was not carried out in an anechoic environment. Even in liquid-fuel spray combustion , the acoustic source may be represented by a collection of monopoles as suggested by (1.1).…”

“…The combustion noise generated by open turbulent premixed flames has been investigated experimentally Hurle et al 1968;Strahle & Shivashankara 1975;Strahle 1978;Kilham & Kirmani 1979;Kotake & Takamoto 1987Rajaram & Lieuwen 2003;Hirsch et al 2007), theoretically (Bragg 1963;Strahle 1971;Kotake 1975;Strahle 1976;Clavin & Siggia 1991) and numerically (Hirsch et al 2007) in the past. These studies have predominantly tried to develop a semi-empirical correlation for either far-field acoustic power or acoustic efficiency.…”

“…The exponents can vary from one study to another. In general, b 1 and b 5 are of order one; b 2 varies from −0.14 (Strahle & Shivashankara 1975) to 0.04 (Strahle 1978); b 3 is suggested to be one in an earlier study (Strahle & Shivashankara 1975) and has been revised to be −1.2 in a later review (Strahle 1978) and b 4 varies from 2 to 3. The values of these exponents depend on how the fluctuating heat release rate is modelled and uses an assumption that the large (integral) scale turbulence is involved in the generation of combustion noise.…”

On the Space-Time Correlation of Heat Release Rate in Turbulent Premixed Flames

“…Roberts and Leventhall, 1973;Strahle and Shivashankara, 1975;Strahle, 1978;Putnam, 1976;Kilham and Kirmani, 1979;Swaminathan et al, 2011,a;. However, the source mechanisms for combustion noise are still less understood compared with aerodynamic noise (for example, jet noise), and its prediction remains a challenging issue.…”

Estudio CFD de la resonancia en la cámara de combustión de Motores Diesel HDI

“…En la referencia [182], se presenta una teoría simple, en la que una llama esquemática puede llegar a la situación límite de tener una superficie nula. Se considera válida esta representación, ya que las longitudes de las ondas emitidas siempre son grandes en comparación con el volumen de la llama.…”