Non-invasive, spatially averaged temperature measurements of falling acetone droplets in nitrogen atmosphere at elevated pressures and temperatures

Preusche, Andreas; Dreizler, Andreas; Steinhausen, Christoph; Lamanna, Grazia; Stierle, Rolf

doi:10.1016/j.supflu.2020.105025

Cited by 6 publications

(18 citation statements)

References 21 publications

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“…The droplet measurement value of V LIFP,i is then put into the equation for the estimated temperature using LIFP T LIFP , with the fit parameters for an equivalent energy density E UV to determine the temperature. This calibration method was found to be pressure independent within discernible precision and accuracy [23].…”

Section: Discussionmentioning

confidence: 87%

“…This maximum is reached when the entire fluorescence peak is imaged from it's beginning. A more detailed description of the setup is available in [23].…”

Section: Discussionmentioning

confidence: 99%

“…Following the approach proposed by Mysik [17], these measurements enable us, for the first time, to assess the importance of volume viscosity in the liquid-like supercritical region and may lead to improved closure models for modelling momentum transport and dissipation effects in supercritical fluids. Finally, the temperatures derived from non-resonant, spontaneous Raman scattering data and laser induced fluorescence and phosphorescence thermometry (LIFP) data provided by Preusche et al [23] are employed to validate the theoretical prediction of an improved evaporation model. It is important to emphasise, that only the temporal evolution of the droplet temperature can be validated, since the presented measurements do not allow droplet size investigations.…”

Section: Introductionmentioning

confidence: 99%

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Experimental Investigations of Near-critical Fluid Phenomena by the Application of Laser Diagnostic Methods

Lamanna

Steinhausen

Preusche

et al. 2022

Fluid Mechanics and Its Applications

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Physics of supercritical fluids is extremely complex and not yet fully understood. The importance of the presented investigations into the physics of supercritical fluids is twofold. First, the presented approach links the microscopic dynamics and macroscopic thermodynamics of supercritical fluids. Second, free falling droplets in a near to supercritical environment are investigated using spontaneous Raman scattering and a laser induced fluorescence/phosphorescence thermometry approach. The resulting spectroscopic data are employed to validate theoretical predictions of an improved evaporation model. Finally, laser induced thermal acoustics is used to investigate acoustic damping rates in the supercritical region of pure fluids.

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Section: Discussionmentioning

confidence: 87%

“…This maximum is reached when the entire fluorescence peak is imaged from it's beginning. A more detailed description of the setup is available in [23].…”

Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Experimental Investigations of Near-critical Fluid Phenomena by the Application of Laser Diagnostic Methods

Lamanna

Steinhausen

Preusche

et al. 2022

Fluid Mechanics and Its Applications

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“…Several laser diagnostic methods have been developed and improved. Spontaneous Raman scattering [2] and combined laser induced fluorescence and phosphorescence [36] enabled the measurement of gas composition in the wake of an evaporating droplet, gas temperatures and, for the case of acetone, mean droplet temperatures. Laser-induced thermal acoustics has been extended to enable the measurement of the acoustic damping rates in the supercritical region of pure fluids [56].…”

Section: Transcritical Evaporation and Mixing Processesmentioning

confidence: 99%

Collaborative Research on Droplet Dynamics Under Extreme Ambient Conditions

Schulte

Dreizler

Munz

et al. 2022

Fluid Mechanics and Its Applications

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A fundamental understanding of droplet dynamics is important for the prediction and optimization of technical systems involving drops and sprays. The Collaborative Research Center (CRC) SFB-TRR 75 was established in January 2010 to focus on the dynamics of basic drop processes, and in particular on processes involving extreme ambient conditions, for example near thermodynamic critical conditions, at very low temperatures, under the influence of strong electric fields, or in situations involving extreme gradients of the boundary conditions. The goal of the CRC was to gain a profound physical understanding of the essential processes, which is the basis for new analytical and numerical descriptions as well as for improved predictive capabilities. This joint initiative involved scientists at the University of Stuttgart, the TU Darmstadt, the TU Berlin, and the German Aerospace Center (DLR) in Lampoldshausen. This first chapter provides a brief overview of the overall structure of this CRC as well as a summary of some selected scientific achievements of the subprojects involved. For further details the reader is referred to the subsequent chapters of this book related to the individual subprojects.

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“…In this paper, we provide new insight into the turbulence development and diffusive transport characteristics of supercritical cryogenic jets. We will focus our analysis to single specie cryogenic fluids, as phase transition in mixtures is governed by more complex mechanisms 23,24 and the research is still in preliminary stages with respect to the thermophysical properties of mixtures of supercritical fluids 17,25 . Our aim is to provide answers to three fundamental questions that are still open regarding the nature of these jets:…”

Section: Introductionmentioning

confidence: 99%

Unpicking the interplay of turbulence, diffusion, and thermophysics in cryogenic jets at supercritical pressures

et al. 2021

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Cryogenic supercritical fluids represent an intriguing category of fluids that combine mechanical and thermophysical properties of both ultra low temperature conditions as well as phenomena taking place well above the critical point. Recent research has demonstrated that it is a common misconception to consider the supercritical state as one homogeneous state. Instead these fluids consist of two to four liquid and gas like phases, each with their own unique characteristics. In our work we investigate numerically single specie cryogenic fluid jets -initially at subcritical temperatureswhich are injected into a supercritical environment (both the pressure and temperature exceed the thermodynamic critical state). For the investigation, a new solver namely "CoolFoam" has been developed which is designed for compressible non-isothermal two-fluid simulations where diffusive transport of heat and/or mass are accounted for. Real fluid thermodynamics are modelled using a polynomial fitting approach developed in our previous work. We introduce also a new phase characterisation framework based on the association of phases with specific temperature ranges (rather than using a single line like the Widom line) which allowed us to better identify similarity effects between the various conditions. We analyse the inter-dependence of the underlying phenomena: density gradient and diffusive mass transport (molecular and thermo(Soret)-diffusion) and turbulence. We also compared supercritical N 2 with subcritical liquid and gas jets to highlight potential differences with respect to how these jets behave. We find that the jet dynamics are largely dictated by the thermodynamic transition of the injected fluid and the associated variation in thermophysical properties. Recently new evidence relevant to the behaviour of cryogenic jets has been produced based both on numerical and experimental efforts. Banuti has presented a detailed thermo-

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Non-invasive, spatially averaged temperature measurements of falling acetone droplets in nitrogen atmosphere at elevated pressures and temperatures

Cited by 6 publications

References 21 publications

Experimental Investigations of Near-critical Fluid Phenomena by the Application of Laser Diagnostic Methods

Experimental Investigations of Near-critical Fluid Phenomena by the Application of Laser Diagnostic Methods

Collaborative Research on Droplet Dynamics Under Extreme Ambient Conditions

Unpicking the interplay of turbulence, diffusion, and thermophysics in cryogenic jets at supercritical pressures

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