MEASUREMENT AND SPECTRAL ANALYSIS OF PRESSURE–TIME VARIATION IN A VALVELESS PULSED COMBUSTOR

✍ Scribed by J.A. Olorunmaiye; M.J.E. Salami

• Publisher: Elsevier Science
• Year: 1997
• Tongue: English
• Weight: 396 KB
• Volume: 11
• Category: Article
• ISSN: 0888-3270
• DOI: 10.1006/mssp.1996.0059

✦ Synopsis

Pressure-time variations were measured at six axial locations in a propane-fuelled SNECMA-Lockwood valveless pulsed combustor. Two techniques were used to acquire the data. The collected data were preprocessed and then analysed by using the fast Fourier transform (FFT) and parametric modeling techniques so as to examine the frequency distribution of the pressure waves at each location. A spectral matching technique is proposed for analysis to ensure accurate frequency estimation. The estimated power spectra of the collected data were found to have peaks close to 220 Hz and at harmonically related frequencies in all the considered locations. Since the presence of higher frequency harmonics in the pressure spectra at the ports in the tailpipe shows that an appreciable proportion of the fuel is burned there, the definition of combustion intensity for pulsed combustors should be based on the whole volume of the combustor rather than the volume of the combustion chamber only. The enhancement of convective heat transfer in the tailpipe due to combustion-driven oscillations can be attributed to the presence of higher frequency harmonics there. Consequently, the combustor is expected to generate broadband acoustical signals having spectral peaks at 220 Hz and its harmonics.