An investigation of thermodynamic states during high-pressure fuel injection using equilibrium thermodynamics

Qiu, Longqing; Reitz, Rolf D.

doi:10.1016/j.ijmultiphaseflow.2015.01.011

Cited by 101 publications

(67 citation statements)

References 77 publications

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“…Dahms and Oefelein [2], and later Dahms [3] used this assumption for their simulation study of supercritical jets. Qiu and Reitz [4] used an extended adiabatic mixing assumption, which includes phase instabilities and phase separation for their study on high pressure fuel injection.…”

Section: Raman Scatteringmentioning

confidence: 99%

“…Our thermodynamic model is based on the true adiabatic mixing temperature calculation by Qiu and Reitz [4], which takes phase stability into account and uses the PC-SAFT equation of state (EOS). The PC-SAFT EOS is formulated as a fundamental equation in the Helmholtz energy utilizing results from statistical physics [13].…”

Section: Assessment Of Thermodynamic Modelsmentioning

confidence: 99%

“…Consideration of the molecular structure allows for good qualitative and quantitative representation of thermodynamic properties with a minimum number of parameters. Since Qiu and Reitz [4] used the Peng-Robinson EOS, figure 4 shows a direct comparison of the theoretical adiabatic mixing temperature calculated by Qiu and Reitz and the PC-SAFT EOS. The fluid system consist of a dodecane-nitrogen mixture at 60 bar and 900 K ambient pressure and temperature, respectively.…”

Section: Assessment Of Thermodynamic Modelsmentioning

confidence: 99%

“…A similar re-evaluation of the experimental results using the thermodynamic model of Dahms [3] is currently in development but not yet published. In this paper we will focus on the thermodynamic model presented by Qiu and Reitz [4]. The measured concentration field in the droplet wake is complemented with an estimation of the temperature field to provide insight into the role of evaporation on the droplet's surface temperature evolution.…”

Section: Characterization Of the Droplet Wakementioning

confidence: 99%

“…The measured concentration field in the droplet wake is complemented with an estimation of the temperature field to provide insight into the role of evaporation on the droplet's surface temperature evolution. The temperature field is estimated using the concentration data applying the theoretical adiabatic mixing assumption by Qiu and Reitz [4]. The data is afterwards fitted by an iteration of the initial droplet temperature using the adiabatic mixing assumption at constant chamber conditions.…”

Section: Characterization Of the Droplet Wakementioning

confidence: 99%

See 4 more Smart Citations

Experimental Investigation of Droplet Injections in the Vicinity of the Critical Point: A comparison of different model approaches

Steinhausen

Lamanna

Stierle

et al. 2017

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

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The disintegration process of liquid fuel within combustion chambers is one of the most important parameters for efficient and stable combustion. Especially for high pressures exceeding the critical value of the injected fluids the mixing processes are not fully understood yet. Recently, different theoretical macroscopic models have been introduced to understand breakdown of the classical two phase regime and predict the transition from evaporation to a diffuse-mixing process. In order to gain deeper insight into the physical processes of this transition, a parametric study of free-falling n-pentane droplets in an inert nitrogen atmosphere is presented. Atmospheric conditions varied systematically from sub-to supercritical values with respect to the fluid properties. An overlay of a diffuse lighted image with a shadowgram directly in the optical setup (front lighted shadowgraphy) was applied to simultaneously detect the presence of a material surface of the droplet as well as changes in density gradients in the surrounding atmosphere. The experimental investigation illustrates, that the presence of a material surface cannot be shown by a direct shadowgram. However, reflections and refractions caused by diffuse ambient illumination are able to indicate the presence of a material surface. In case of the supercritical droplet injections in this study, front lighted shadowgraphy clearly revealed the presence of a material surface, even when the pre-heated droplets are released into a supercritical atmosphere. This detection of the droplet interface indicates, that the droplet remains subcritical in the region of interest, even though it is injected into a supercritical atmosphere. Based on the adiabatic mixing assumption recent Raman-scattering results in the wake of the droplet are re-evaluated to compute the temperature distribution. Presented experimental findings as well as the re-evaluation of recent Raman scattering results are compared to thermodynamic models to predict the onset of diffuse-mixing and supercritical disintegration of the droplet. Additionally, a one dimensional evaporation model is used to evaluate the validity of the adiabatic mixing assumption in the estimation of the droplet temperature. The presented findings contribute to the understanding of recent theoretical models for prediction of spray and droplet disintegration and the onset of diffuse-mixing processes. Keywords Front lighted Shadowgraphy, Raman-scattering, Supercritical fluid injection IntroductionThe disintegration process of liquid droplets in a high pressure and high temperature environment is one of the most important parameters for stable and efficient combustion. Therefore, the behaviour of droplets in such an environment has long been a matter of analytical, numerical and experimental investigation. Especially the transition process from a two phase behaviour of the droplet or jet to a diffusion dominated mixture is not yet well understood. Recently, three different models predicting the onset of this diffuse-mixing...

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Section: Raman Scatteringmentioning

confidence: 99%

Section: Assessment Of Thermodynamic Modelsmentioning

confidence: 99%

Section: Assessment Of Thermodynamic Modelsmentioning

confidence: 99%

Section: Characterization Of the Droplet Wakementioning

confidence: 99%

Section: Characterization Of the Droplet Wakementioning

confidence: 99%

See 3 more Smart Citations

Experimental Investigation of Droplet Injections in the Vicinity of the Critical Point: A comparison of different model approaches

Steinhausen

Lamanna

Stierle

et al. 2017

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

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On the Consideration of Diffusive Fluxes Within High-Pressure Injections

Föll

Gerber

Munz

et al. 2020

Notes on Numerical Fluid Mechanics and Multidisciplinary Design

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Mixing characteristics of supercritical injection studies were analyzed with regard to the necessity to include diffusive fluxes. Therefore, speed of sound data from mixing jets were investigated using an adiabatic mixing model and compared to an analytic solution. In this work, we show that the generalized application of the adiabatic mixing model may become inappropriate for subsonic submerged jets at high-pressure conditions. Two cases are discussed where thermal and concentration driven fluxes are seen to have significant influence. To which extent the adiabatic mixing model is valid depends on the relative importance of local diffusive fluxes, namely Fourier, Fick and Dufour diffusion. This is inter alia influenced by different time and length scales. The experimental data from a high-pressure n-hexane/nitrogen jet injection were investigated numerically. Finally, based on recent numerical findings, the plausibility of different thermodynamic mixing models for binary mixtures under high pressure conditions is analyzed.

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Modeling and Simulation of a Turbulent Multi-component Two-phase Flow Involving Phase Change Processes Under Supercritical Conditions

Kuetemeier

Sadiki

2022

Fluid Mechanics and Its Applications

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The present paper aims at developing a generally valid, consistent numerical description of a turbulent multi-component two-phase flow that experiences processes that may occur under both subcritical and trans-critical or supercritical operating conditions. Within an appropriate LES methodology, focus is put on an Euler-Eulerian method that includes multi-component mixture properties along with phase change process. Thereby, the two-phase flow fluid is considered as multi-component mixtures in which the real fluid properties are accounted for by a composite Peng-Robinson (PR) equation of state (EoS), so that each phase is governed by its own PR EoS. The suggested numerical modelling approach is validated while simulating the disintegration of an elliptic jet of supercritical fluoroketone injected into a helium environment. Qualitative and quantitative analyses are carried out. The results show significant coupled effect of the turbulence and the thermodynamic on the jet disintegration along with the mixing processes. Especially, comparisons between the numerical predictions and available experimental data provided in terms of penetration length, fluoroketone density, and jet spreading angle outline good agreements that attest the performance of the proposed model at elevated pressures and temperatures. Further aspects of transcritical jet flow case as well as comparison with an Eulerian-Lagrangian approach which is extended to integrate the arising effects of vanishing surface tension in evolving sprays are left for future work.

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An investigation of thermodynamic states during high-pressure fuel injection using equilibrium thermodynamics

Cited by 101 publications

References 77 publications

Experimental Investigation of Droplet Injections in the Vicinity of the Critical Point: A comparison of different model approaches

Experimental Investigation of Droplet Injections in the Vicinity of the Critical Point: A comparison of different model approaches

On the Consideration of Diffusive Fluxes Within High-Pressure Injections

Modeling and Simulation of a Turbulent Multi-component Two-phase Flow Involving Phase Change Processes Under Supercritical Conditions

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