09. Heat and Mass Transfer

Turbulent Jets are one of the most basic flows used in the industry and have a wide range of applications. Examples include combustion engines, chemical mixing, air curtains, and other applications. Combustion engines and chemical mixing require high mixing performance for more efficient reactions. However, air curtains require low diffusion performance and small velocity decay. Thus, various jet characteristics are required, and various control methods have been proposed to improve these characteristics. Among these control methods is the intermittent jet, which is known to improve mixing performance owing to the vortex rings generated by intermittent issuing. On the other hand, multiple jets are used in many practical applications. In the case of multiple jets, unlike single jets, the jets issued from multiple nozzles interfere with each other downstream, and thus the mixing performance is significantly affected by each other's jets. However, the effect of intermittent control on such multiple jets has not been fully investigated. In this study, the effect of frequency on the flow in a multiple intermittent jet consisting of two round jets, each with a different intermittent frequency, was investigated using DNS when the frequency was varied. The results show that the introduction of different frequencies improves the uniformity of the flow.

Prof.

Mamoru Takahashi