Experimental Study on Combustion Characteristics and Pressure Oscillations of Turbulent Jet Ignition in a Confined Space

ABSTRACT

Flame shapes, flame tip velocities and pressure oscillations with turbulent jet ignition (TJI) combustion were studied comprehensively in a newly designed constant-volume combustion bomb (CVCB) by employing high-speed Schlieren photography. In the CVCB, the pre-chamber was effective at accelerating the flame and promoting turbulent flame formation. The results show that when the jet flame departs from the jet orifice, the flame tip velocity naturally decreases, mainly due to the fluid dynamic mechanism. And a temporal acceleration due to the emergence of additional flame wrinkles is observed at high pressures. When the initial pressure is sufficiently high, pressure waves can be distinguished clearly. The continuous wavelet transform suggests that a 1–3 kHz bandpass filter can be used to filter the pressure oscillation. Comparing pre-chambers with different holes reveals that intense pressure waves are formed with an increase in the number of jet orifices, and the propagating flame can be pushed backward during the interaction between the forward flame and the reflected pressure wave due to the reduced flame tip velocity and increased pressure wave intensity.

KEYWORDS:

• Turbulent jet ignition
• pressure oscillation
• confined space

Acknowledgments

The work is supported by National Natural Science Foundation of China (Grant No. 91641203, 91741119), Tianjin Natural Science Foundation (Grant No. 20JCYBJC01110). This work is also supported by the National Science Fund for Distinguished Young Scholars (Grant No. 51825603)

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Additional information

Funding

This work was supported by the National Natural Science Foundation of China [91641203, 91741119]; Tianjin Natural Science Foundation [20JCYBJC01110]; National Science Fund for Distinguished Young Scholars [51825603].