Experimental Research On Dynamic Behavior Of Deformable Boundary Flow

This article is based separately on channel flow and flow around cylinder to study the flow field property influenced by deformable boundary, which correspond to the deformable boundary inner and outer flow. The deformable boundary inner and outer flow devices were researched through modification and design of existing equipment. The unsteady incoming flow(periodical flow) and steady incoming flow were designed due to boundary deformation mode of channel flow. Spatial dynamic behavior was analyzed based on inner and outer boundary deformation motion, which include vortex shedding frequency of flow field, mean velocity, turbulence intensity, flow field energy, flow visualization and nonlinear phase diagram analysis, and compared data processing results of two kinds of deformable boundary flow. It revealed the dynamic behavior of the deformable boundary flow and the relationship between boundary deformation characteristic and flow characteristic. It also provided reliable experimental basis of related theory and numerical study.The results showed that boundary deformation can control the frequency of vortex shedding frequency of flow field in the channel. Frequency multiplication relationship was not change with the speed and the spatial position under the same flow profile. The mean velocity showed increasing and smooth phenomenon with the increasing of frequency of boundary deformation in low speed zones. While in medium and high speed zones, the trend is slow decay and smooth. Turbulence intensity suppression was found when Re=13906 and Re=19262 at unsteady incoming flow, and when Re=12051 and Re=16693 at steady incoming flow. The suppression parameter range of flow energy was calculated. Secondary vortex phenomenon was found at steady flow. Three-dimensional phase trajectory evolution was gained under two kinds of incoming flows, and the scale of ?joint‘ in singular limit cycle was controlled by sub harmonic amplitude.In deformable boundary outer flow, boundary deformation of flow around cylinder can inhibit the frequency of Karman Vortex Street, and suppression became stronger with Reynolds increasing. The mean velocity was reduced and the turbulence intensity was increased with the increasing of frequency of boundary deformation. The affected area of Karman Vortex Street was defined, and the length of the affected area was calculated when Re=125,153,209,267,288,324,472. The relationship between frequency of boundary deformation and the affected area was obtained. Three-dimensional phase trajectory evolution was gained under two kinds of modes.For the deformable boundary flow, no matter channel flow or flow around cylinder, the ratio between frequency of boundary deformation and harmonic frequency of flow field is 0.5 or related multiple relationships.