A paper describes direct numerical simulations (DNSs) of three-dimensional mixing-layer flows undergoing transition to turbulence; the mixing layers may or may not be laden with evaporating liquid drops. In contrast to most studies in this field, the general case is investigated here where both the gas and the liquid drops' composition encompasses a very large number of species. The simulations were performed using a mathematical model discussed in several prior NASA Tech Briefs articles; the prior studies described a laminar mixing layer, whereas the present study describes a mixing layer that has all attributes of turbulence. The model includes governing equations in an Eulerian and a Lagrangian reference frame for the gas and drops, respectively. To mathematically describe the myriad of species, the model relies on continuous thermodynamics concepts. The paper succinctly reiterates the model and discusses results of the new numerical simulations. Comparisons are performed with previous single-species similar simulations and with the laminar simulations using the same model. The paper presents several conclusions, the main one being that differences between single- and multi-species turbulent flows having the same initial conditions are so significant that neither experiments on, nor theoretical studies of, single-species flows are adequate as surrogates for studies of multi-species flows.
This work was done by Josette Bellan and Laurent Selle of Caltech for NASA's Jet Propulsion Laboratory. For more information, download the Technical Support Package (free white paper) at www.techbriefs.com/tsp under the Physical Sciences category.
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Refer to NPO-42632, volume and number of this NASA Tech Briefs issue, and the page number.
This Brief includes a Technical Support Package (TSP).
DNNs of Multicomponent Gaseous and Drop-Laden Mixing Layers Achieving Transition to Turbulence
(reference NPO-42632) is currently available for download from the TSP library.
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Overview
The document is a Technical Support Package from NASA's Jet Propulsion Laboratory (JPL) concerning the research and development of Direct Numerical Simulations (DNNs) related to multicomponent gaseous and drop-laden mixing layers that achieve transition to turbulence. It is identified by the NTR Number 42632 and is part of NASA Tech Briefs, which disseminates aerospace-related technological advancements with broader scientific and commercial applications.
The focus of this research is on understanding the complex interactions within mixing layers that contain multiple gaseous components and liquid droplets. These mixing layers are critical in various aerospace applications, including combustion processes, atmospheric phenomena, and the design of efficient propulsion systems. The transition to turbulence in these layers is a significant area of study, as turbulence affects the performance and efficiency of aerospace vehicles.
The document emphasizes the importance of DNNs in providing detailed insights into the fundamental mechanisms governing turbulence and mixing processes. By simulating these phenomena at a high level of fidelity, researchers can gain a deeper understanding of the underlying physics, which can lead to improved models and predictions for real-world applications.
Additionally, the Technical Support Package outlines the potential for these findings to contribute to advancements in technology and science, highlighting the relevance of the research to both the aerospace sector and other industries. It encourages collaboration and innovation through the NASA Innovative Partnerships Program, which aims to facilitate the transfer of technology and knowledge from NASA to commercial entities.
For further inquiries or assistance regarding this research area, the document provides contact information for the Innovative Technology Assets Management at JPL, including a mailing address, telephone number, and email.
Overall, this Technical Support Package serves as a valuable resource for understanding the dynamics of multicomponent mixing layers and their transition to turbulence, showcasing NASA's commitment to advancing aerospace technology and fostering innovation through research.
