Sergey Martynov

Thermodynamic interpolation for the simulation of two-phase flow of non-ideal mixtures

This paper describes the development and application of a technique for the rapid interpolation of thermodynamic properties of mixtures for the purposes of simulating two-phase flow. The technique is based on adaptive inverse interpolation and can be applied to any Equation of State and multicomponent mixture. Following analysis of its accuracy, the method is coupled with a two-phase flow model, based on the homogeneous equilibrium mixture assumption, and applied to the simulation of flows of carbon dioxide (CO2) rich mixtures. This coupled flow model is used to simulate the experimental decompression of binary and quinternary mixtures. It is found that the predictions are in good agreement with the experimental data and that the interpolation approach provides a flexible, robust means of obtaining thermodynamic properties for use in flow models.

A geometrically based grid refinement technique for multiphase flows

Abstract An adaptive mesh refinement technique developed for the solution of scalar problems is extended to the simulation of two-phase flow problems, as a means of reducing the computational runtime associated with such problems. The methodology, involving the adaptive partition of the domain into uniformly discretised regions, is extended to systems of equations without increase in algorithmic complexity. By application first to the simpler case of the Euler equations of gas dynamics, the technique is shown to handle shocks without loss of accuracy and to result in significant CPU runtime reductions of over 90%. Application to more complex two-phase flow problems, including the flashing flow during the decompression of a pipeline, also show dramatic increase in computational performance.

Spray dynamics as a multi-scale process

The analysis of the processes in sprays, taking into account the contribution of all spatial and temporal scales, is not feasible in most cases due to its complexity. The approach used in most applications is based on separate analysis of the processes at various scales, and the analysis of the link between these processes. This approach is demonstrated for the analysis of spray break-up and penetration in Diesel engine-like conditions, and vortex ring-like structures in gasoline engine-like conditions. The conventional WAVE, TAB, stochastic and modified WAVE (taking into account transient effects) models are reviewed. It is pointed out that the latter model leads to the prediction of spray penetration in Diesel engine-like conditions closest to the one observed experimentally. In gasoline engine-like conditions, spray penetration is often accompanied by the formation of vortex ring-like structures, the spatial scale of which is comparable with the scale of spray penetration. The general expression of the velocity of the vortex ring centroid can be simplified for short and long times, the latter simplification being particularly simple and useful for engineering applications. The thickness of the vortex ring is expressed as l = atb, where a is an arbitrary constant and 1/4 ≤ b ≤ 1/2. The cases when b = 1/2 and b = 1/4 refer to laminar and turbulent vortex rings respectively. The model is compatible with the observation of vortex ring-like structures in gasoline engine-like conditions.

Optimal Valve Spacing for Next Generation CO2 Pipelines

Pipeline transportation is considered as the primary mode of transporting CO2 for future carbon capture and storage (CCS) projects. The failure of such pipelines could lead to the release of a significant amount of inventory, which in high enough concentrations is toxic and presents a significant risk to life. To mitigate this hazard, emergency shutdown valves (ESDVs) are installed at regular intervals along the pipeline, to minimise the amount of inventory released in the event of failure. This paper presents a methodology and the required metrics for optimising valve spacing as a trade-off between the reduction in hazard against the cost of installation and maintenance.