Abstract:

In order to explore the Ledinegg instability of the micro-channels of different corrugated wall surfaces, computer numerical control was used to process three types of micro-channels of wall surfaces, namely sine wave, triangle wave and ordinary smooth micro-channels. R141b was used as the experimental working medium to conduct the flow heat transfer experiments under the conditions of pressure of 40—80kPa, heat flux of 13.281—22.138kW/m² and inlet temperature of 33℃. The experimental results showed that the negative slope of pressure drop-flow curve in triangular ripple micro channel has the lowest slope, and the mass flux at the onset of flow instability (OFI) is the largest, and Ledinegg instability is most likely to occur, while the normal smooth micro channel is the opposite. In addition, with the increase of heat flux, the slope of the negative slope region of the pressure drop-flow curve of the micro channel decreases, and the mass flux at OFI increases, indicating that the increase of heat flux will increase the instability of the system. With the increase of system pressure, the negative slope area of pressure drop-flow curve of the micro channel became gentler, while the mass flux at OFI did not change much, indicating that increasing system pressure was beneficial to the stability of the system.

Key words: corrugated wall, Ledinegg instability, starting point of flow instability, micro-channels

摘要：

为探究不同波纹壁面微细通道的Ledinegg不稳定性，利用计算机数控加工得到3种壁面的微细通道，分别是正弦波纹、三角形波纹与普通光滑微细通道。采用R141b为实验工质，在压力为40~80kPa、热通量为13.281~22.138kW/m²、入口温度为33℃条件下开展流动换热实验。结果表明：三角形波纹微细通道的压降-流量曲线负斜率区斜率最小，流动不稳定起始点（OFI）质量流量最大，最容易发生Ledinegg不稳定性，而普通光滑微细通道与之相反。另外，随着热通量增大，微细通道的压降-流量曲线负斜率区斜率减小，OFI点质量流量增大，表明增大热通量会增加系统的不稳定性；随着系统压力增大，微细通道的压降-流量曲线负斜率区更加平缓，而OFI点质量流量变化不大，表明增大系统压力有利于提高系统的稳定性。

关键词: 波纹壁面, Ledinegg不稳定性, 流动不稳定起始点, 微细通道