Flame front analysis of high-pressure turbulent lean premixed methane-air flames
30th International Symposium on Combustion, Abstracts of Symposium Papers, Chicago, IL, Amerika Birleşik Devletleri, 25 - 30 Temmuz 2004, ss.68, (Tam Metin Bildiri)
- Yayın Türü: Bildiri / Tam Metin Bildiri
- Basıldığı Şehir: Chicago, IL
- Basıldığı Ülke: Amerika Birleşik Devletleri
- Sayfa Sayıları: ss.68
- Orta Doğu Teknik Üniversitesi Adresli: Evet
Özet
An experimental study on lean turbulent premixed methane-air flames at high pressure was carried out using a turbulent Bunsen flame configuration. Laser Doppler Anemometry measurements of the cold flow indicated the turbulence intensities and the integral length scale were not sensitive to pressure. Due to the decreased kinematic viscosity with increasing pressure, the turbulent Reynolds numbers increased and isotropic turbulence scaling indicated a large decrease of the smallest turbulence scales. Available experimental results and PREMIX code computations indicated a decrease of the laminar flame propagation velocities with increasing pressure, essentially between 1 and 0.5 MPa. Instantaneous flame images and their analysis showed that pressure increase generated small-scale flame structures. The variance of the flamelet curvatures, the standard deviation of the flamelet orientation angle, and the flamelet crossing lengths vary linearly with the ratio between large and small turbulence scales and indicated the strong effect of this parameter on premixed turbulent flame dynamics and structure. An obvious consequence was the increase of the flame surface density and hence burning rate with pressure, as confirmed by its direct determination from two-dimensional tomographic images.