An experimental study on the effects of needle dynamics on the penetration of a high-pressure methane jet

The effect of high-pressure injection variations on the mixing state of underexpanded methane jets

“…Beyond these differences, the jet tip penetration, the spreading rate of the jet, the axial decay of the fuel and the local mixing state can be Table 2. Subset of the matrix of nominal operating conditions from the Schlieren campaign of Vera-Tudela et al 30 (Table 1 consistently captured to very good agreement with the experiment at all operating conditions. By extension, the aspects of jet self-similarity in the far-field that are captured in the experiments can also be observed in the CFD results and are therefore not shown.…”

“…A detailed schematic as well as the descriptions of the internal compartments and design parameters of the injector and of the high pressure circuit can be found in. 30 Figure 1 shows a schematic of the system used for the seeding of acetone into the injection fluid. Methane coming from the high-pressure circuit is led to a junction followed by two needle valves which regulate the amount of seeded and unseeded gas that will be fed into the injector.…”

“…This steady-state flow rate is attained earlier at higher P inj , because the needle lift is faster. 30 Figure 11(b) shows the temporal evolution of injected methane mass in the CVC, calculated again from the simulations. All mass flow rates at a given P inj collapse onto each other.…”

“…In all cases, the faster jet penetration is also accompanied by faster volumetric growth rate, as shown in Figure 12). The injector dynamics also play some role in propagation speed and volumetric growth: the needle lift is faster at higher P inj , while being rather insensitive to the P ch 30 However, they do not fundamentally alter the picture of the physics, which is conveyed by equations ( 6) and ( 8), which will be discussed next.…”

The Flex-OeCoS—a Novel Optically Accessible Test Rig for the Investigation of Advanced Combustion Processes under Engine-Like Conditions

“…The new test rig is intended to fill the gap among: (1) constant volume cells (which are not suitable for premixed or dual fuel combustion); (2) rapid compression and expansion machines (which are limited in operating pressure and the achievable in-cylinder flow fields/turbulence levels); Constant volume, high pressure and high temperature cells such as the HTDZ (high temperature and high pressure cell) [6][7][8][9], or the much larger SCC (spray combustion chamber) [10][11][12][13], are valuable tools to investigate fundamental processes related to diffusion combustion with liquid fuel or high-pressure gas jets [14]. Experiments with premixed or dual fuel combustion however are very difficult due to long residency time of the ignitable fuel air mixture at high temperatures (in electrically heated cells), or because the pre-combustion required to reach high gas temperatures consumes all fuel present in the cell before the actual experiment (i.e., liquid fuel injection/ignition).…”