We present the experimental study of convection in a horizontal liquid layer (ethanol, 3-mm deep), evaporating from a localized surface (10 × 10 mm²) into the gas flow (air). Visualization and measurements of the two-component velocity field in the liquid layer has been carried out with the Particle Image Velocimetry (PIV) technique. In our experiments we consider a novel configuration in which the gas-liquid interface is maintained in the flat position in the confined square area and the volatile liquid evaporates from the planar surface into the gas flowing along the surface. We also consider the effect of the gas velocity (0.0138–0.138 m/s) and the gas and the liquid temperature (20 °C - 50 °C) on the convective flow structure within the liquid layer. It is shown that the gas velocity and both, the gas and the liquid temperatures induce significant changes in the convective flow structure. We give the first experimental proof of the phenomenon that the motion of the gas-liquid interface goes along the counter-current direction to the gas flow as theoretically predicted. The analysis of the experimental data shows that the influence of the gas flow velocity on the Marangoni convection at the maximum temperature (50 °C) is significantly reduced owing to the growth of the diffusion resistance for the gas flow under a strong evaporation from the interface. As a result, it leads to the low surface temperature gradient, which decreases thermocapillary stresses and the circulation velocity of the first (thermocapillary) vortex within the fluid layer. Further, we observe that the disappearance of the second convective vortex circulating in the same direction with the gas flow. The governing factor, determining the structure of convective flows within the liquid is the thermocapillary effect due to the intensive evaporation provided that the cooling and the temperature distribution are uniform on the gas-liquid interface.

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PIV技术在蒸发液层到气流中对流运动的实验研究

我们介绍了从局部表面（10×10 mm ²）蒸发的水平液体层（乙醇，深度3 mm）中对流的实验研究）流入气流（空气）。液体层中两组分速度场的可视化和测量已经使用粒子图像测速技术（PIV）进行了。在我们的实验中，我们考虑了一种新颖的配置，其中气-液界面在受限的正方形区域内保持在平坦位置，并且挥发性液体从平坦表面蒸发成沿表面流动的气体。我们还考虑了气体速度（0.0138–0.138 m / s）和气体以及液体温度（20°C-50°C）对液层内对流流动结构的影响。结果表明，气体速度以及气体和液体温度都引起对流流动结构的显着变化。我们提供了理论上预测的气液界面运动沿与气流相反的方向流动的现象的第一个实验证明。对实验数据的分析表明，由于在界面强烈蒸发下气流的扩散阻力增大，在最高温度（50°C）下气体流速对Marangoni对流的影响显着降低。 。结果，导致低的表面温度梯度，这降低了热毛细管应力和流体层内第一个（热毛细管）涡旋的循环速度。此外，我们观察到第二对流涡旋的消失与气流的流动方向相同。控制因素，