Experimental data of flash boiling liquid nitrogen sprays (Test Case IN-1)

The flash boiling process of superheated liquid nitrogen (LN2) under high-altitude conditions was investigated with the help of a cryogenic temperature adjustment system and injection system at the test bench M3.3 at DLR Lampoldshausen. The test fluid LN2 reaches its superheated condition by varying the injection temperature or by a low-pressure environment in the vacuum chamber of the test bench. This cylindrical chamber with an inner diameter of 300 mm provides four optical accesses to visualize the sprays and their morphology by high-speed shadowgraphy and by laser-based Phase-Doppler diagnostics (PDA). For the present testcase, highly superheated LN2 sprays with constant injection conditions were generated. By means of PDA the local distributions of the mean droplet velocities and diameters within the flash boiling sprays were measured.

在DLR Lampoldshausen的M3.3测试平台上，借助低温调节系统和注入系统，研究了高海拔条件下过热液氮（LN2）的闪蒸过程。通过改变注入温度或通过测试平台真空室中的低压环境，测试流体LN2达到过热状态。该内径为300毫米的圆柱形室提供了四个光学通道，通过高速阴影图形和高斯激光相位多普勒诊断（PDA）技术，可视化喷嘴及其形态。对于本次测试案例，在恒定的注入条件下生成了高度过热的LN2喷嘴。通过PDA技术，测量了闪蒸喷嘴内局部平均液滴速度和直径的分布。