Study of the mixing and dilution characteristics of a RQL (rich-quench-lean) combustor in its quenching zone in an aeroengine

Under the operating condition of a sector-shaped section in a RQL model combustor being in a combination of various main stream air speeds and quenching jet flow air speeds, with acetone serving as the fluorescence particles, a PLIF (plane laser-induced fluorescence) visualization experimental study was performed of the acetone concentration field in the cold-state quenching zone and the distribution of the acetone concentration in the centerline cross section of a quenching hole was obtained. The law governing the influence of the main stream and quenching jet flow air speed on the mixing and dilution characteristics i. e. relative penetration depth and the mixing and dilution non-uniformity was observed and a contrast analysis was performed of the following two circumstances, i. e. the main stream having and having no swirling flows. It has been found that the results measured by using the PLIF technology can be used to apparently compare the mixing and dilution characteristics under various operating conditions. When a swirling flow is present in the main stream, to increase the quenching jet flow air speed can increase the relative penetration depth and quickly enhance the mixing and dilution uniformity, however, after the quenching jet flow air speed has reached a certain value, the mixing and dilution uniformity in the quenching zone will increase slowly or even remain unchanged. To increase the air speed of the main stream will decrease the relative penetration depth and the notably worsen the mixing and dilution uniformity. Compared with the circumstance that a swirling flow is present in the main stream, when no swirling flows are present in the main stream, the relative penetration depth will become smaller and the mixing and dilution uniformity will become worse, thus the mixing and dilution effectiveness will be not good.