Affiliations: Department of Mechanical Engineering, Kagoshima
University, 1-21-40 Korimoto, Kagoshima 890-0065, Japan.
Abstract: Experiments were conducted on the effects of a wall distance and
velocity ratio of suction flow to injection flow on the flow and heat transfer
characteristics of a circular impinging jet accompanying an annular suction
flow. As a result, it is found that in the case of accompanying suction flow, a
higher Nusselt number can be obtained compared with in the case without suction
flow, under a condition of the wall distance within eight times of injection
pipe diameter from the near pipe exit edge. In addition, when the effect of
velocity ratio is examined at a fixed arbitrary wall distance, it is found that
there exists an optimum velocity ratio where the Nusselt number becomes the
maximum. It is shown that these heat transfer characteristics are closely
associated with the fluctuating velocity and the mean velocity in the
two-dimensional velocity field observed by Particle Image Velocimetry
(PIV).