Experimental investigation of high-pressure hydrogen gas jet impingement characteristics of single-hole cylindrical injector

High-pressure hydrogen direct injection technology can enable an internal combustion engine to attain high thermal efficiency and discharge clean emissions; hence, the advantages provided by hydrogen jet impingement are crucial. This paper presents an experimental investigation of the high-pressure hydrogen direct injection from a single-hole cylindrical injector. A test rig with a spring set was designed based on the impulse conservation law to test important high-pressure hydrogen jet impingement parameters, such as jet impingement force and impulse. The results show that the hydrogen gas jet exhibits a two-zone behavior. In Zone I (near-field dynamic region), the jet impulse is not conservative, and the jet characteristic parameters (jet impingement force and impulse) fluctuate-first decreasing and then increasing. In Zone II, the jet impulse is conservative. This two-zone jet feature is induced by shockwaves because a high-pressure hydrogen jet with a high nozzle pressure ratio reaches its sonic speed at the nozzle outlet. The Mach disk height is the inflection point of these two zones. Moreover, the hydrogen injection pressure has a considerable influence on the gas jet. As the injection pressure increases, the hydrogen jet impingement force and impulse increase. Both jet parameters have a linearly increasing relationship with injection pressure.