Analysis of high-pressure Diesel fuel injection processes using LES with real-fluid thermodynamics and transport

Lacaze, Guilhem; Misdariis, Antony; Ruiz, Anthony; Oefelein, Joseph C.

doi:10.1016/j.proci.2014.06.072

Cited by 94 publications

(48 citation statements)

References 30 publications

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“…This eliminates numerical contamination of the subfilter models due to artificial dissipation and provides discrete conservation of mass, momentum, energy, and species, which is imperative for high quality LES. Representative results and case studies using RAPTOR can be found in studies by Oefelein et al [47,46,44,43,45], Williams et al [64], Lacaze et al [35], and Khalil et al [34]. Sample results for the jet-in-crossflow problem are presented in Fig.…”

Section: Large-eddy Simulation Solver: Raptormentioning

confidence: 94%

Global Sensitivity Analysis and Estimation of Model Error, Toward Uncertainty Quantification in Scramjet Computations

Huan¹,

Safta²,

Sargsyan³

et al. 2018

AIAA Journal

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The development of scramjet engines is an important research area for advancing hypersonic and orbital flights. Progress toward optimal engine designs requires accurate flow simulations together with uncertainty quantification. However, performing uncertainty quantification for scramjet simulations is challenging due to the large number of uncertain parameters involved and the high computational cost of flow simulations. These difficulties are addressed in this paper by developing practical uncertainty quantification algorithms and computational methods, and deploying them in the current study to large-eddy simulations of a jet in crossflow inside a simplified HIFiRE Direct Connect Rig scramjet combustor. First, global sensitivity analysis is conducted to identify influential uncertain input parameters, which can help reduce the systems stochastic dimension. Second, because models of different fidelity are used in the overall uncertainty quantification assessment, a framework for quantifying and propagating the uncertainty due to model error is presented. These methods are demonstrated on a nonreacting jet-in-crossflow test problem in a simplified scramjet geometry, with parameter space up to 24 dimensions, using static and dynamic treatments of the turbulence subgrid model, and with two-dimensional and three-dimensional geometries.

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Section: Large-eddy Simulation Solver: Raptormentioning

confidence: 94%

Global Sensitivity Analysis and Estimation of Model Error, Toward Uncertainty Quantification in Scramjet Computations

Huan¹,

Safta²,

Sargsyan³

et al. 2018

AIAA Journal

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“…A multi-component benchmark case is the Spray-A of the Engine Combustion Network (www.sandia.gov/ECN), where cold n-dodecane is injected into a warm nitrogen atmosphere at a pressure of 6 MPa, which exceeds the critical pressure of both components. Different modelling approaches, e.g., Lagrangian particle tracking in Wehrfitz et al [9], a single-phase dense gas approach in Lacaze et al [10] and a two-phase approach based on a vapor-liquid equilibrium model in Matheis and Hickel [11], have been used to simulate this test case. Up to now, none of these approaches is commonly accepted because of a common disagreement on the actual state of the fluid or the mixture.…”

Section: Introductionmentioning

confidence: 99%

Experimental and Numerical Investigation of Phase Separation due to Multi-Component Mixing at High-Pressure Conditions

Traxinger

Müller

Pfitzner

et al. 2017

Proceedings ILASS–Europe 2017. 28th Conference on Liquid Atomization and Spray Systems

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Experiments and numerical simulations were carried out in order to contribute to a better understanding and prediction of high-pressure injection into a gaseous environment. Specifically, the focus was put on the phase separation processes of an initially supercritical fluid due to the interaction with its surrounding. N-hexane was injected into a chamber filled with pure nitrogen at 5 MPa and 293 K and three different test cases were selected such that they cover regimes in which the thermodynamic non-idealities, in particular the effects that stem from the potential phase separation, are significant. Simultaneous shadowgraphy and elastic light scattering experiments were conducted to capture both the flow structure as well as the phase separation. In addition, large-eddy simulations with a vaporliquid equilibrium model were performed. Both experimental and numerical results show phase formation for the cases, where the a-priori calculation predicts two-phase flow. Moreover, qualitative characteristics of the formation process agree well between experiments and numerical simulations and the transition behaviour from a dense-gas to a spray-like jet was captured by both.Keywords elastic light scattering, shadowgraphy, large-eddy simulation, Peng-Robinson, tangent plane distance IntroductionInjection into a high-pressure gaseous environment is a crucial process within energy conversion machines. Nowadays, many fluid flow devices are operated at pressures that exceed the critical pressure pc of the involved pure fluids. The increase in operating pressure in aircraft and car engines mainly stems from the demand for higher engine efficiency and reduced CO2 emissions. The main reason for rising the chamber pressure in liquid rocket engines (LREs) is the proportionality between operating pressure and specific impulse [1]. Typically, the operating pressure in LREs is supercritical with respect to both fuel and oxidizer (p > pc), whereas the injection temperature may be sub-or supercritical, corresponding to liquid-like or gas-like states. At supercritical pressure, the fluid properties, such as density, enthalpy and viscosity, are highly non-linear functions of temperature and pressure. Furthermore, phase separation due to non-linear interaction of the different components may occur. The phenomenon of phase separation due to mixing at high pressures is well-known in process engineering. Remarkably, up to now, high-pressure fuel injection into a gaseous environment is not completely understood and no commonly accepted theoretical approach exists. Within the past 20 years, many research groups have focused on understanding the behaviour of jets at high pressures using experimental and numerical methods. Chehroudi et al. [2] injected cryogenic nitrogen into gaseous nitrogen at sub-and supercritical pressures. Based on shadowgraphy visualizations, they observed classical twophase phenomena at subcritical pressure indicated by very fine ligaments and droplets being ejected from the jet. As the pressure exceeds the cr...

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“…His findings showed that in the case of typical diesel conditions the mixing path associated with all states during injection never crossed the liquid-vapor regime, suggesting that interfacial mixing layer dynamics are locally supercritical. Using similar numerical techniques, Lacaze el al [5] further showed mixing processes that were significantly modified by the real-fluid thermodynamics. It was suggested that the large density ratio between the supercritical fuel and the ambient gas leads to significant penetration of the jet with enhanced turbulent mixing at the tip and strong entrainment effects.…”

Section: Introductionmentioning

confidence: 98%

Transcritical mixing and auto-ignition of n-dodecane fuel using a diffuse interface method

Bravo

Peter

Ihme

et al. 2018

2018 Joint Propulsion Conference

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High-fidelity simulations of transcritical spray mixing and auto ignition in a combustion chamber are performed at high pressure and temperature conditions using a recently developed finite rate LES solver. The simulation framework is based on a diffused-interface (DI) method that solves the compressible multi-species conservation equations along with the Peng Robinson state equation and real-fluid transport properties. A finite volume approach with entropy stable scheme is employed to accurate simulate the nonlinear real fluid flow. LES analysis is performed for non-reacting and reacting spray conditions targeting the ECN Spray A configuration at chamber conditions with a pressure of 60 bar and temperatures between 800 K and 1200 K to investigate effects of the real-fluid environment and low-temperature chemistry. Comparisons with measurements in terms of global spray parameters and mixture fraction distributions demonstrates the accuracy in modeling the turbulent mixing behavior. Good overall agreement of the autoignition process is obtained from simulation results at different ambient temperature conditions and the formation of intermediate species is captured by the simulations, indicating that the presented numerical framework adequately reproduces the corresponding low-and-high-temperature ignition processes under high-pressure conditions that are relevant to realistic diesel fuel injection systems.

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Analysis of high-pressure Diesel fuel injection processes using LES with real-fluid thermodynamics and transport

Cited by 94 publications

References 30 publications

Global Sensitivity Analysis and Estimation of Model Error, Toward Uncertainty Quantification in Scramjet Computations

Global Sensitivity Analysis and Estimation of Model Error, Toward Uncertainty Quantification in Scramjet Computations

Experimental and Numerical Investigation of Phase Separation due to Multi-Component Mixing at High-Pressure Conditions

Transcritical mixing and auto-ignition of n-dodecane fuel using a diffuse interface method

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