Laboratory tests on streamwise vortex-induced vibration (VIV) of a flexible, slender cylinder were carried out in a towing tank. A cylinder model, 20 mm in diameter and 3.91 m in length, was towed horizontally to generate a uniform profile of relative velocity in calm water. The aspect ratio (length to diameter) and mass ratio (structural mass to displaced fluid mass) of the cylinder were 195.5 and 1.39, respectively. The Reynolds number was in the range of 1000-3000. The displacement amplitudes and vibration frequencies were investigated in order to examine the dynamic characteristics of the flexible cylinder undergoing streamwise VIV. Experimental results indicated that there were two detached branches in the streamwise response curve, i.e., the first excitation region (1.0 < Vr < 2.6) and the second excitation region (2.6 < Vr < 4.0). This phenomenon is similar to the streamwise VIV of an elastically-mounted rigid cylinder, except that a larger and shifted peak was observed in the second branch in this study. The cylinder's linear orbits in the first excitation region indicated that the streamwise vibration frequency was equivalent to its transverse counterpart. However, in the second excitation region, the cylinder's motion showed a figure-of-eight pattern, and the streamwise frequency was twice that in the transverse direction. In addition, two curve-fitted formulae of the maximum displacement amplitudes in the first and second excitation regions, versus the reduced mass-damping parameter, were proposed. This was accomplished by compiling the published streamwise VIV data and those in the present research work.

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The traditional radiation air conditioning system has some problems, such as easy condensation, insufficient refrigeration capacity, complex structure, and control system. Therefore, this study proposes a new type of finned metal radiant plate with large heat flow per unit area, sufficient cooling capacity, and simplified heat exchange system, in order to realize large temperature difference between cooling and heating. The temperature field uniformity and thermal comfort test of a novel type of finned ceiling radiant panel and independent fresh air linked air conditioning system under summer cooling and winter heating circumstances are accomplished through artificially generated climate environments. The study's findings demonstrate that in the radiation and fresh air modes, the maximum interior temperature differential under cooling conditions does not rise over 2.1°C. The maximum temperature differential in the space at any one moment in the radiation and fresh air modes cannot be greater than 3°C when heating conditions are present. The fresh air's cooling and dehumidifying effects are clear. The dehumidification efficiency may reach 50%, and the moisture content ranges from 5.48 to 9.63 g/kg. With PMV ranging from −0.34 to 0.54, the enhanced air conditioning system in this research provides exceptionally good thermal comfort. Additionally, the finned radiant panel's installation area occupies just 14% of the ceiling, which is sufficient to fulfill the room's cooling and heating load needs as well as provide high thermal comfort and consistent indoor temperature. The theoretical investigation and practical implementation of the direct expansion radiant air conditioning system are both strongly supported by this research.