To obtain super/transcritical water jet characteristics, large eddy simulations (LES) are performed for the process of cool water injection into high-temperature environment under supercritical pressure. Jets with different density ratio under supercritical pressure are compared in terms of instantaneous flow field, mean flow properties, turbulence characteristics and heat transfer characteristics. Results show that under the present conditions (Froude number $Fr$< 50), compared with the initial momentum, buoyancy effect has a greater influence on the jet flow, and jet with higher density difference can obtain a higher jet velocity, thus achieving better heat transfer and mixing. Meanwhile, the enhancement of turbulence weakens the influence of high density gradient layer on jet stability. In addition, acceleration causes jet to contract at the outlet, enhancing radial turbulence and heat transfer.

为了获得超/跨临界水射流特性，对超临界压力下向高温环境中注入冷水的过程进行了大涡模拟（LES）。比较了超临界压力下不同密度比的射流的瞬时流场、平均流动特性、湍流特性和传热特性。结果表明，在目前条件下（弗劳德数$Fr$< 50), 与初始动量相比, 浮力效应对射流的影响更大, 密度差越大的射流可以获得更高的射流速度, 从而实现更好的传热和混合。同时，湍流的增强减弱了高密度梯度层对射流稳定性的影响。此外，加速会导致射流在出口处收缩，从而增强径向湍流和热传递。