Characteristics of High Pressure Jets for Direct Injection Gas Engine

Visualization and comparison of methane and hydrogen jet dynamics using schlieren imaging

“…8 (a)-(c) shows the effect of pressure ratio by changing the injection pressure at a constant chamber pressure on the jet penetration and cross-sectional area with time evolution. According to the plots of the jet penetration versus time, rising the P i leads to deeper penetration of both H 2 and CH 4 jets which is consistent with the results of several studies i.e., [15,16,17,18,19,20,21,22]. The main reason is that higher injection pressure means a higher pressure ratio and accordingly a higher mass flow.…”

“…As previously stated, the reason is that at lower injection pressures, H 2 easily diffuses in all directions whereas CH 4 mostly diffuses axially because of the momentum effect due to its greater molecular weight [10,37,38]. It should be also mentioned that although the higher injection pressures lead to a higher jet momentum, the wider jet cone angle can cause a stronger aerodynamic drag that limits both the jet penetration and tip velocity [15]. The other noticeable point is that although H 2 and CH 4 physical properties are not similar, the trend of their penetration is extremely close to each other, especially during the injection time.…”

“…The other noticeable point is that although H 2 and CH 4 physical properties are not similar, the trend of their penetration is extremely close to each other, especially during the injection time. That is because the jet development phase is mostly affected by the initial momentum [15] and gases start to follow their intrinsic diffusion after the end of injection (valve closure). Even after the end of injection, the maximum difference between H 2 and CH 4 penetration remains only 11% atP i = 80 bar andP ch = 10 bar.…”

“…Direct injection can resolve this problem by injecting the fuel during and/or after the inlet valve closure [10,9]. Furthermore, the direct injection concept can eliminate the possibility of backfire [11] and knocking [12] of the port fuel injection hydrogen engines [10] and lead to higher thermal efficiency as well as lower engine emissions and fuel consumption in natural gas engines [8,13,14,15,16].…”

Generation of Turbulence in a RCEM towards Engine Relevant Conditions for Premixed Combustion Based on CFD and PIV Investigations

“…compressed natural gas (CNG), pure methane, hydrogen, or a combination thereof [30]. In [31] planar laser induced fluorescence (PLIF) has been used to investigate the influence of the injection pressure on the flow structure and turbulent mixing. Considering numerical simulations, the high pressure and velocity gradients and the small structures require a fine mesh and small associated time steps and therefore, come at a very high computational cost.…”