The effect of swirl on lifted flames in a nonpremixed jet has been studied experimentally by rotating a nozzle to generate a continuous swirl. A model for turbulent lifted flames, based on turbulent large scale structure, is extended to account for the effect of swirl in the prediction of lift-off heights. Results show that the lift-off height decreases linearly with nozzle rotational speed in turbulent jets. The model for swirl jets predicts that a normalized lift-off height depends solely on swirl number, and experimental results substantiate this prediction. For laminar jets, the lift-off height shows a nonlinear dependence on nozzle rotational speed and becomes independent of jet velocity as the swirl number increases. These characteristics are attributed to the jet breakup behavior in swirl jets.
ASJC Scopus subject areas
- Chemical Engineering(all)
- Fuel Technology
- Energy Engineering and Power Technology
- Physics and Astronomy(all)