Large-Eddy Simulation of Coaxial LN2/GH2 Injection at Trans- and Supercritical Conditions

Müller, Hagen; Pfitzner, Michael; Matheis, Jan; Hickel, Stefan

doi:10.2514/6.2015-0843

Cited by 8 publications

(4 citation statements)

References 27 publications

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“…2 shows that the PR-EoS as well as the SRK-EoS can only predict a limited number of alkanes from the homologue series within an acceptable error [22,23]. Generally, the density/compressibility factor prediction of the SRK-EoS is better for simple fluids like methane CH 4 and hydrogen H 2 , while the PR-EoS gives superior results for longer alkanes like n-hexane C 6 H 14 . This finding can be further emphasized by comparing the isotherms of these different fluids over a wide pressure range, see Fig.…”

Section: Real-gas Modelingmentioning

confidence: 99%

“…Pioneer work was done by Oefelein and Yang [1] as well as Zong et al [2]. Many research groups, e.g., Schmitt et al [3] and Müller et al [4], have followed their method and used the dense-gas approach to do LES at rocket engine relevant conditions. More recently, Matheis and Hickel [5] and Traxinger et al [6] applied a vapor-liquid equilibrium (VLE) model and showed that phase separation due to non-linear mixing phenomena is likely to occur at typical injection conditions of diesel and rocket engines.…”

Section: Introductionmentioning

confidence: 99%

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Real-Gas Effects and Phase Separation in Underexpanded Jets at Engine-Relevant Conditions

Traxinger

Banholzer

Pfitzner

2018

2018 AIAA Aerospace Sciences Meeting

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A numerical framework implemented in the open-source tool OpenFOAM is presented in this work combining a hybrid, pressure-based solver with a vapor-liquid equilibrium model based on the cubic equation of state. This framework is used in the present work to investigate underexpanded jets at engine-relevant conditions where real-gas effects and mixture induced phase separation are probable to occur. A thorough validation and discussion of the applied vapor-liquid equilibrium model is conducted by means of general thermodynamic relations and measurement data available in the literature. Enginerelevant simulation cases for two different fuels were defined. Analyses of the flow field show that the used fuel has a first order effect on the occurrence of phase separation. In the case of phase separation two different effects could be revealed causing the single-phase instability, namely the strong expansion and the mixing of the fuel with the chamber gas. A comparison of single-phase and two-phase jets disclosed that the phase separation leads to a completely different penetration depth in contrast to single-phase injection and therefore commonly used analytical approaches fail to predict the penetration depth.

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Section: Real-gas Modelingmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Real-Gas Effects and Phase Separation in Underexpanded Jets at Engine-Relevant Conditions

Traxinger

Banholzer

Pfitzner

2018

2018 AIAA Aerospace Sciences Meeting

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“…Large Eddy Simulations (LES) have been used to investigate the supercritical and transcritical nonreacting flow behavior. [19][20][21][22][23][24][25] Muller et al 19 have shown that the transcritical flows typically exhibit strong density gradients that delay the instability growth and can lead to a redistribution of turbulence kinetic energy from the radial to the axial flow direction. Largarza-Cortes et al 20 performed LES to compare the transcritical and supercritical flows of the Mayer et al experiments.…”

Section: Introductionmentioning

confidence: 99%

Numerical study of the pseudo-boiling phenomenon in the transcritical liquid oxygen/gaseous hydrogen flame

Zeinivand

Farshchi

2020

Proceedings of the Institution of Mechanical Engineers, Part G:

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The interactions and effects of turbulent mixing, pseudo-boiling phenomena, and chemical reaction heat release on the combustion of cryogenic liquid oxygen and gaseous hydrogen under supercritical pressure conditions are investigated using RANS simulations. Comparisons of the present numerical simulation results with available experimental data reveal a reasonably good prediction of a supercritical axial shear hydrogen-oxygen flame using the standard k-ε turbulence model and the eddy dissipation concept combustion model with a 23 reaction steps kinetics for H2-O2 reaction. The present simulation qualitatively reproduced oxygen injection and its reaction with the co-flowing hydrogen, which is characterized by rapid flame expansion, downstream flame propagation, and expansion induced flow recirculation. Several turbulence models were used for numerical simulations. It is shown that the selection of an appropriate turbulence model for transcritical reacting flows is crucial and far more important than for subcritical reacting flows. It is indicated that the pseudo-boiling phenomena is the main reason for the considerable differences between the turbulence models in a transcritical flame. Also, it is demonstrated that the liquid oxygen core disappears faster in a non-reacting flow than in a reacting flow. The shear layer in the non-reacting flow is much stronger than reacting case; providing a large transfer of energy from the outer layer to the inner layer. At the supercritical injection conditions, the difference between the turbulence models is much less than the transcritical injection conditions.

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“…In the present work, we employ the volume-translation method of Abudour et al [14] which is based on the work of Chou and Prausnitz [15]. This method has already been used in our previous LES studies of supercritical nitrogen injection [16] as well as of inert coaxial LN 2 /GH 2 injection [17].…”

Section: Introductionmentioning

confidence: 99%

A flamelet model for transcritical LOx/GCH₄flames

Müller

Pfitzner

2017

J. Phys.: Conf. Ser.

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Abstract. This work presents a numerical framework to efficiently simulate methane combustion at supercritical pressures. A LES flamelet approach is adapted to account for real-gas thermodynamics effects which are a prominent feature of flames at near-critical injection conditions. The thermodynamics model is based on the Peng-Robinson equation of state (PR-EoS) in conjunction with a novel volume-translation method to correct deficiencies in the transcritical regime. The resulting formulation is more accurate than standard cubic EoSs without deteriorating their good computational performance. To consistently account for pressure and strain fluctuations in the flamelet model, an additional enthalpy equation is solved along with the transport equations for mixture fraction and mixture fraction variance. The method is validated against available experimental data for a laboratory scale LOx/GCH 4 flame at conditions that resemble those in liquid-propellant rocket engines. The LES result is in good agreement with the measured OH * radiation. IntroductionTodays main stage liquid-propellant rocket engines (LRE) typically operate at supercritical pressures, i.e., at chamber pressures that exceed the critical pressure of the propellants, and at cryogenic injection temperatures. One or both of the propellants are thus injected at near-critical conditions and mixing, ignition and combustion are affected by non-ideal thermodynamic effects. In particular, the thermodynamic-and transport properties, e.g., density, enthalpy, viscosity, are highly non-linear functions of temperature and pressure. Moreover, the experiments of Mayer et al. [1,2] showed that the surface tension between liquid and vapor is diminished at sufficiently high pressures and mixing is characterized by continuous-phase diffusion rather than by two-phase spray atomization. In these diffusion mixing layers, the fluid properties change drastically and the density may vary by two orders of magnitude within a few micrometers.Such configurations pose a serious challenge for numerical as well as for experimental studies. At the same time, their investigation is important to better understand the involved processes and to develop tools that help in the design of LREs, but also of other high pressure combustion devices, such as novel Diesel motors or gas turbines. The topic received considerable attention in the last decade and several valuable experiments were carried out. Thorough overviews are given, for instance, by Oschwald et al. [5] focusing on the Mascotte testing facility. Along with the better understanding that has been generated by the experimental efforts, several groups developed models and numerical tools to perform simulations of near-critical mixing and combustion allowing for a detailed view on the flow. Among the first to conduct large-eddy simulations (LES) of supercritical injection was Oefelein and Yang [6] and later Zong et al. [7] as well as Oefelein [8]. These studies showed that the accurate treatment of thermodynamic non-idealities are ke...

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Large-Eddy Simulation of Coaxial LN2/GH2 Injection at Trans- and Supercritical Conditions

Cited by 8 publications

References 27 publications

Real-Gas Effects and Phase Separation in Underexpanded Jets at Engine-Relevant Conditions

Real-Gas Effects and Phase Separation in Underexpanded Jets at Engine-Relevant Conditions

Numerical study of the pseudo-boiling phenomenon in the transcritical liquid oxygen/gaseous hydrogen flame

A flamelet model for transcritical LOx/GCH₄flames

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Large-Eddy Simulation of Coaxial LN2/GH2 Injection at Trans- and Supercritical Conditions

Cited by 8 publications

References 27 publications

Real-Gas Effects and Phase Separation in Underexpanded Jets at Engine-Relevant Conditions

Real-Gas Effects and Phase Separation in Underexpanded Jets at Engine-Relevant Conditions

Numerical study of the pseudo-boiling phenomenon in the transcritical liquid oxygen/gaseous hydrogen flame

A flamelet model for transcritical LOx/GCH4flames

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A flamelet model for transcritical LOx/GCH₄flames