Molecular Simulations to Research Supercritical Fuel Properties

Molecular Dynamics Simulations of Vapor–Liquid Interface Properties ofn-Heptane/Nitrogen at Subcritical and Transcritical Conditions

“…The results show that the difference in results caused by changing nitrogen models was much smaller than the differences that resulted from changing models for n -alkanes. Overall, the results show that for binary mixtures of n -alkane/nitrogen, the SKS model had the best overall performance over a wide range of temperatures and pressures . Since the present manuscript concerns the study of the vapor–liquid interface behavior of n -heptane/nitrogen under equilibrium conditions, it was deemed reasonable to use the VLE experimental data of n -alkane/nitrogen mixtures as a base for selecting a potential model, which is the reason why the combination of SKS model for n -alkanes and Rivera 2002 (a two-site L–J model) for nitrogen was chosen.…”

“…A recent study by Qiao et al evaluated the performance of several commonly used potential models based on the estimated VLE of four n -alkane/nitrogen mixtures, including n -heptane/nitrogen, n -decane/nitrogen, n -dodecane/nitrogen, and n -hexadecane/nitrogen. Four models for n -alkane were considered, including TraPPE-UA by Martin and Siepmann, NERD by Nath et al, SKS by Smit et al, and OPLS-UA Jorgensen et al Different nitrogen models were also compared, including TraPPE-N2 (two-site L–J model), Shadman (central L–J model), and Firanescu (central L–J model) .…”

“…Modern rockets, such as the Raptor engine developed by SpaceX, make use of a full-flow staged combustion cycle and can reach a combustion chamber pressure of around 300 bar. Under such conditions, the injected liquid fuel may experience a transcritical or supercritical state, as a result of which the governing mechanisms during mixing, evaporation, and combustion will also change. , For example, at low pressures, a distinctive vapor–liquid interface always exists, but as pressure increases, the interface broadens and eventually disappears. − At pressures very close to or beyond the critical point of the mixture, the surface tension vanishes, thereby marking the onset of diffusion-dominated supercritical mixing. , The vapor–liquid interfacial dynamics, especially for mixtures relevant to propulsion applications under extreme conditions, which has not been well understood yet, plays an important role in understanding the mixing, phase transition, and combustion processes. ,, …”

On the potential and challenges of laser-induced thermal acoustics for experimental investigation of macroscopic fluid phenomena

“…The latter have received increased attention in the past decade, as the recently published literature shows (Falgout et al 2016;Müller et al 2016;Baab et al 2016Baab et al , 2018Crua et al 2017). Since the main objectives are evaporation and disintegration processes of liquid fluids at pressures and temperatures either close to or exceeding their critical points, quantitative data for validation of numerical simulations have recently become a research concern with increasing interest (Bork et al 2017;Lamanna et al 2018;Steinhausen et al 2019;Stierle et al 2020;Nomura et al 2020;Lamanna et al 2020;Qiao et al 2020). Microscopic investigations by Santoro and Gorelli (2008), Simeoni et al (2010) as well as Bencivenga et al (2009) made it possible to distinguish various regions above the critical pressure, as is depicted in Fig.…”

Vapor–liquid equilibrium estimation of n-alkane/nitrogen mixtures using neural networks

“…Phase equilibrium calculations play a crucial role in the study of high-pressure liquid fuel injection processes, involving a number of complex physical processes such as mixing, atomization and evaporation [1][2][3][4]. Understanding of phase equilibrium behavior, specifically, vapor-liquid equilibrium (VLE) forms an important premise in the design of distillation processes, widely used in the chemical industry [5].…”