الفهرس 
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Abstract
Partially premixed flames (PPFs) are commonly used in many practical combustion systems,such as jet engines, gas turbines and internal combustion engines. PPFs show an enhanced stability due to the interaction between their non-uniform structure that involves the lean and rich pockets. In the present study, highly turbulent partially premixed flames are stabilized using a concentric flow conical nozzle (CFCN) burner. The previous works focused on investigating the stabilization mechanism at a certain turbulence level. However, this study is devoted to investigate the performance of the CFCN burner at higher level of turbulence closer to many practical applications. The stability characteristics are studied. In addition, the flow field and temperature field are experimentally investigated above the conical nozzle exit using 2D PIV and type B thermocouple, respectively. Two turbulence levels and five different levels of partial premixing are investigated. Six turbulent partially premixed flames, at fixed level of partial premixing and turbulence level have been investigated in more details at Reynolds numbers range between 5.9×103 and 8.9×103 and equivalence ratio ranges between 3 and 4.5. The reactive case is compared with the non-reactive case. Moreover, the heat release effects on the flow structure are investigated. The relationship between vorticity/strain rate and reaction zone are examined. The flame stability is slightly improved using the present burner configuration. The optimum stability characteristics are obtained at L/D = 2.5. Furthermore, the stability mechanism of conical nozzle burner is not likely affected by the flame speed only. The NG flames exhibit higher stability than those of the LPG. The flow in reactive case exhibits higher flow divergence which leads to improve the flame stability. The centerline axial velocity increases in reactive case by a factor of 1.5-4 higher than that of the non-reactive case. Moreover, the reactive case reaches a reduction in the turbulent Reynolds number by a factor of 4-5.5. The peaks of temperature field, vorticity field and minimum principal strain rate field are strongly related to the reaction zone. The principle compressive strain rate is aligned at approximately 45° with respect to the flow direction.