Liquid jet impingement is used for cooling and cleaning in various industrial branches. The advantages of jet impingement include high heat and mass transport rates in the vicinity of the impingement point. Pulsating liquid jets impinging on horizontal substrates with a pulsation frequency around 100 Hz have been shown to increase the cooling efficiency in comparison to jets with continuous mass flow rates. The influence of jet pulsation on cooling efficiency for impingement of horizontal jets onto vertical walls has not yet been investigated. In the case of a vertical heated wall, gravity contributes to the liquid flow pattern. In particular, if the time span between two pulses is sufficiently long, the liquid drainage from the region above the impingement point can contribute to heat transport without increasing the average flow rate of the cooling medium. In this work, the influence of pulsations on heat transfer during impingement of a horizontal liquid jet onto a vertical wall is investigated experimentally for the pulsation frequency range 1–5 Hz. The results regarding increase of heat transfer efficiency are related to flow patterns developing by impingement of successive pulses, as well as to the liquid splattering.

液体喷射撞击用于各种工业部门的冷却和清洁。射流撞击的优点包括在撞击点附近的高热量和高传质速率。与连续质量流量的射流相比，脉动液体射流以100 Hz左右的脉动频率撞击水平基板，已显示出可提高冷却效率。尚未研究射流脉动对冷却效率的影响，以将水平射流撞击到垂直壁上。在垂直加热壁的情况下，重力有助于液体流动方式。特别是，如果两个脉冲之间的时间跨度足够长，从撞击点以上区域排出的液体可有助于热量传输，而不会增加冷却介质的平均流量。在这项工作中，在1-5 Hz的脉动频率范围内，通过实验研究了在水平液体射流撞击垂直壁的过程中，脉动对传热的影响。与传热效率增加有关的结果与通过连续脉冲的撞击而形成的流型以及液体的喷溅有关。