Ali Moghaddas

Bio: Ali Moghaddas is an academic researcher from Northeastern University. The author has contributed to research in topics: Laminar flow & Laminar flame speed. The author has an hindex of 12, co-authored 15 publications receiving 449 citations.

Laminar burning speeds of ethanol/air/diluent mixtures

Abstract: Laminar burning speed of ethanol/air/diluent mixtures have been measured over a wide range of temperature, pressure, fuel air equivalence ratio and diluent. Experimental facilities include a cylindrical vessel with two large end windows and a spherical vessel with capability to withstand pressures up to 425 atm. Both of these vessels are heated for having initial temperatures of unburned gas up to 500 K. A shadowgraph system with a CMOS camera capable of taking pictures up to 40,000 frames/s is used to observe structure of propagating flames. Pressure rise due to combustion in both vessels is used to calculate laminar burning speed of the mixture. A thermodynamic model is used to calculate burning speed from combustion pressure. Laminar burning speeds of ethanol/air premixed mixtures have been measured at high temperatures and pressures. A mixture of 86% nitrogen and 14% carbon dioxide, which simulate heat capacity of residual gases in internal combustion engines, is used to determine the effect of diluent on burning speed. A correlation for laminar burning speed as a function of temperature, pressure, equivalence ratio and extra diluent gas (EDG) has been developed. The range of temperature and pressure are 300–650 K and 1–5 atm, fuel air equivalence ratio 0.8–1.1 and extra diluent gases of 5% and 10%. The measured values compare very well with available data and extend the range many folds.

Measurement of Laminar Burning Speeds and Investigation of Flame Stability of Acetylene (C2H2)/Air Mixtures

Abstract: Laminar burning speeds and flame structures of spherically expanding flames of mixtures of acetylene (C2H2) with air have been investigated over a wide range of equivalence ratios, temperatures, and pressures. Experiments have been conducted in a constant volume cylindrical vessel with two large end windows. The vessel was installed in a shadowgraph system equipped with a high speed CMOS camera, capable of taking pictures up to 40,000 frames per second. Shadowgraphy was used to study flame structures and transition from smooth to cellular flames during flame propagation. Pressure measurements have been done using a pressure transducer during the combustion process. Laminar burning speeds were measured using a thermodynamic model employing the dynamic pressure rise during the flame propagation. Burning speeds were measured for temperature range of 300–590 K and pressure range of 0.5–3.3 atm, and the range of equivalence ratios covered from 0.6 to 2. The measured values of burning speeds compared well with existing data and extended for a wider range of temperatures. Burning speed measurements have only been reported for smooth and laminar flames. [DOI: 10.1115/1.4028363]