An experimental study is performed on the transient effectiveness of spoilers in two-dimensional flow. In the preceding study, the influence of actuation time on the transient characteristics of spoiler was pointed out and some hypotheses were assumed to describe those phenomena. In this study those hypotheses are verified by experiments conducted with two types of spoilers (i.e. flap-and retractable arc-type) and in wider range of actuation time. Additional comments are presented as well.
A cushion flow is influenced by the forward speed of ACV. When the experiments are conducted on a closed moving-ground water tunnel, flow visualization is achieved by injecting oil particles (n-Butyl phthalate 81%, kerosene 19%) into the flow. For the subcritical forward speed, the flow pattern on the plane of symmetry of models can be observed, in which the front jet is bifurcated and becomes overfed condition, on the other hand the rear jet becomes underfed condition, respectively. The cushion flow between the front and the rear jets is subdivided into two regions, where there are turblent diffusion flow adjacent to the overfed jet and major channel flow.