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Philippe Desevaux

Bio: Philippe Desevaux is an academic researcher from University of Franche-Comté. The author has contributed to research in topics: Flow visualization & Supersonic speed. The author has an hindex of 10, co-authored 19 publications receiving 503 citations.

Papers
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TL;DR: In this paper, the performance of six well-known turbulence models for the study of supersonic ejectors was evaluated and the results showed that the k-omega-sst model agrees best with experiments.

323 citations

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TL;DR: In this article, the authors present flow imaging techniques developed for investigating flow in ejectors using the laser sheet method but differ from each other by the kind of the illumination source, the polarization direction of the incident light and the type of the scattering tracers.
Abstract: This paper presents flow imaging techniques developed for investigating flow in ejectors. These visualization techniques use the laser sheet method but differ from each other by the kind of the illumination source, the polarization direction of the incident light and the type of the scattering tracers. Each of these methods enables the visualization of specific phenomena (shock structure, flow instabilities, mixing process). Although the flow visualizations are primarily qualitative, they allow the determination of the flow regime, the measurement of the non-mixing length, can indicate suggestions for the design of ejectors and provide the possibility to validate numerical simulations.

56 citations

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TL;DR: In this paper, an optical method which allows the accurate visualization of the mixing zone between two high-speed flows inside an ejector is described, which associates Rayleigh scattering, laser induced fluorescence and image processing.

40 citations

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TL;DR: Graphical Abstracts: as mentioned in this paper, Section 3.1.2.3.1, Section 2.2, Section 4.3, Section 5.4, Section 6.
Abstract: Graphical Abstract

27 citations

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TL;DR: The condensation process is visualized through a numerical model of non-equilibrium condensation in high speed flows implemented by the present authors in a CFD code through which laser tomography visualization is used to validate the computational results.
Abstract: The present study deals with the visualization of the droplet condensation phenomenon that can occur in ejectors powered by moist air. The condensation process is visualized through a numerical model of non-equilibrium condensation in high speed flows implemented by the present authors in a CFD code. The evolution of the region of condensation in the ejector with the primary stagnation pressure is examined both in the case without secondary flows and in the case with free entrainment of induced air. Laser tomography visualization is used to validate the computational results. The effects of some parameters such as the primary stagnation pressure and the humidity ratio in the primary and secondary air flows are also examined. Limitations of the present numerical model are discussed.

16 citations


Cited by
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TL;DR: In this paper, a comprehensive literature review on ejector refrigeration systems and working fluids is presented, which deeply analyzes ejector technology and behavior, refrigerant properties and their influence over ejector performance.
Abstract: The increasing need for thermal comfort has led to a rapid increase in the use of cooling systems and, consequently, electricity demand for air-conditioning systems in buildings. Heat-driven ejector refrigeration systems appear to be a promising alternative to the traditional compressor-based refrigeration technologies for energy consumption reduction. This paper presents a comprehensive literature review on ejector refrigeration systems and working fluids. It deeply analyzes ejector technology and behavior, refrigerant properties and their influence over ejector performance and all of the ejector refrigeration technologies, with a focus on past, present and future trends. The review is structured in four parts. In the first part, ejector technology is described. In the second part, a detailed description of the refrigerant properties and their influence over ejector performance is presented. In the third part, a review focused on the main jet refrigeration cycles is proposed, and the ejector refrigeration systems are reported and categorized. Finally, an overview over all ejector technologies, the relationship among the working fluids and the ejector performance, with a focus on past, present and future trends, is presented.

359 citations

Journal ArticleDOI
TL;DR: A literature review on ejectors and their applications in refrigeration can be found in this article, where a number of studies are grouped and discussed in several topics, i.e. background and theory of ejector and jet refrigeration cycle, performance characteristics, working fluid and improvement of jet refrigerator.
Abstract: This paper provides a literature review on ejectors and their applications in refrigeration. A number of studies are grouped and discussed in several topics, i.e. background and theory of ejector and jet refrigeration cycle, performance characteristics, working fluid and improvement of jet refrigerator. Moreover, other applications of an ejector in other types of refrigeration system are also described.

339 citations

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TL;DR: The physics of droplet ejection under strong evaporative flow is described using simulations of the laser powder bed interactions to elucidate the experimental results and the relevance of vapor driven entrainment of metal micro-particles to similar fluid dynamic studies in other fields of science will be discussed.
Abstract: The results of detailed experiments and finite element modeling of metal micro-droplet motion associated with metal additive manufacturing (AM) processes are presented. Ultra high speed imaging of melt pool dynamics reveals that the dominant mechanism leading to micro-droplet ejection in a laser powder bed fusion AM is not from laser induced recoil pressure as is widely believed and found in laser welding processes, but rather from vapor driven entrainment of micro-particles by an ambient gas flow. The physics of droplet ejection under strong evaporative flow is described using simulations of the laser powder bed interactions to elucidate the experimental results. Hydrodynamic drag analysis is used to augment the single phase flow model and explain the entrainment phenomenon for 316 L stainless steel and Ti-6Al-4V powder layers. The relevance of vapor driven entrainment of metal micro-particles to similar fluid dynamic studies in other fields of science will be discussed.

333 citations

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TL;DR: In this paper, the effects of two important ejector geometry parameters, the primary Nozzle Exit Position (NXP) and the mixing section converging angle θ, on its performance were investigated.

262 citations

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TL;DR: A review of various researches of the mathematical model on the hydrodynamic and thermodynamic character within the ejector can be found in this paper, where various models consisting of ideal assumptions, governing equations, auxiliary conditions, solution methods and main results are presented.
Abstract: In ejector refrigeration systems, the performance of the ejector is critical to the performance, capability, size and cost of the whole system. Construction of mathematical models has been used as an effective method for analyzing the performance of the ejector as well as the whole refrigeration system. These models can also be used to guide system operation, interpret experimental results and assist in system design and optimization. The overall objective of this paper is to provide a review of various researches of the mathematical model on the hydrodynamic and thermodynamic character within the ejector. The paper first briefly describes ejector including fundamental principle, flowing and mixing mechanism and the method of model establishment. Then various models consisting of ideal assumptions, governing equations, auxiliary conditions, solution methods and main results are presented. The models can be classified into two main categories: (i) steady thermodynamic models which can be further subdivided into single-phase flow model and two-phase flow model and (ii) dynamic models which are also subdivided according to the flowing phases considered. It has been shown that the dynamic models have higher prediction precision and give more information compared with the steady thermodynamic models. In addition, the simplified empirical and semi-empirical models based on measured data are briefly discussed. This review is useful for understanding the evolution process and the current status of the mathematical models on ejector and highlighting the key aspects of model improvement such as the mixing mechanism, the capture of the shock wave, etc.

223 citations