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A Study of Scalar Mixing in Gas Phase Turbulent Jets Using High Repetition Rate Imaging.

紀錄類型:	書目-語言資料,手稿 : Monograph/item
正題名/作者:	A Study of Scalar Mixing in Gas Phase Turbulent Jets Using High Repetition Rate Imaging./
作者:	Papageorge, Michael.
面頁冊數:	1 online resource (352 pages)
附註:	Source: Dissertation Abstracts International, Volume: 78-10(E), Section: B.
Contained By:	Dissertation Abstracts International78-10B(E).
標題:	Mechanical engineering. -
電子資源:	click for full text (PQDT)
ISBN:	9781369839531

A Study of Scalar Mixing in Gas Phase Turbulent Jets Using High Repetition Rate Imaging.
Papageorge, Michael.

A Study of Scalar Mixing in Gas Phase Turbulent Jets Using High Repetition Rate Imaging. - 1 online resource (352 pages)

Source: Dissertation Abstracts International, Volume: 78-10(E), Section: B.

Thesis (Ph.D.)

Includes bibliographical references

In this dissertation, high-speed mixture fraction (a conserved flow scalar) and velocity measurements were performed to understand the linked spatio-temporal dynamics of scalar mixing processes in gas-phase turbulent jets. The current research focused on four over-arching topics: (i) design and construction of the high energy pulse burst laser system (HEPBLS), (ii) experimental verification of statistical convergence theory for time-series measurements in turbulent flows and the development of a new "multi-burst" data processing methodology for "short duration" time-series measurements, (iii) development and application of high-speed (10 kHz) two-dimensional mixture fraction imaging for spatio-temporal statistical analysis of scalar mixing, and (iv) development and application of simultaneous high-speed velocity and mixture fraction measurements to understand the space-time coupling between velocity and scalar fluctuations.

Electronic reproduction.
Ann Arbor, Mich. :
ProQuest,
2018

Mode of access: World Wide Web

ISBN: 9781369839531Subjects--Topical Terms:

557493
Mechanical engineering.
Index Terms--Genre/Form:

554714
Electronic books.

A Study of Scalar Mixing in Gas Phase Turbulent Jets Using High Repetition Rate Imaging.
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245 1 2 $a A Study of Scalar Mixing in Gas Phase Turbulent Jets Using High Repetition Rate Imaging.
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300 $a 1 online resource (352 pages)
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500 $a Source: Dissertation Abstracts International, Volume: 78-10(E), Section: B.
500 $a Adviser: Jeffrey Sutton.
502 $a Thesis (Ph.D.) $c The Ohio State University $d 2017.
504 $a Includes bibliographical references
520 $a In this dissertation, high-speed mixture fraction (a conserved flow scalar) and velocity measurements were performed to understand the linked spatio-temporal dynamics of scalar mixing processes in gas-phase turbulent jets. The current research focused on four over-arching topics: (i) design and construction of the high energy pulse burst laser system (HEPBLS), (ii) experimental verification of statistical convergence theory for time-series measurements in turbulent flows and the development of a new "multi-burst" data processing methodology for "short duration" time-series measurements, (iii) development and application of high-speed (10 kHz) two-dimensional mixture fraction imaging for spatio-temporal statistical analysis of scalar mixing, and (iv) development and application of simultaneous high-speed velocity and mixture fraction measurements to understand the space-time coupling between velocity and scalar fluctuations.
520 $a The high-speed measurements presented in this dissertation were facilitated through the design and construction of a new high-energy pulse burst laser system (HEPBLS). The design target of the HEPBLS was ultra-high pulse energy output at high repetition rates for turbulence and combustion imaging diagnostics. Several modifications were made to the original pulse burst concept leading to ultra-high laser pulse energies (> 1 Joule/pulse at 532 nm and 10 kHz) over long burst durations (> 20 ms). The high laser pulse energies enable high-fidelity two-dimensional mixture fraction measurements at 10's of kHz using planar Rayleigh scattering and two-line mixture fraction imaging using spontaneous Raman scattering. While the primary imaging diagnostics used the second-harmonic (532 nm) output from the HEPBLS, it is noted that high-energy ultra-violet (266, 355 nm) output was demonstrated as well. The result is a flexible system capable of facilitating a wide range of laser diagnostic techniques at 10's of kHz that have not been available previously. Convergence of turbulent flow statistics from finite-record length time-series measurements was examined via theory and experiment. Analytical solutions of the convergence of statistical moments and correlation functions were developed and experimentally verified for the first time, providing a practitioner a method for accurately estimating the uncertainty of a measurement for a given record length. In addition, a new "multi-burst" data processing method was proposed (and experimentally validated) based on combined ensemble and time-series statistics specifically targeted for shorter-duration time-series measurements characteristic of data acquired using the HEPBLS.
520 $a Scalar mixing dynamics was first examined using high-speed (10 kHz) planar Rayleigh scattering imaging in a series of turbulent propane jets. In this manner, quantitative two-dimensional measurements of the mixture fraction field were collected for jets with Reynolds numbers of Red = 10000, 20000, and 30000 with high signal-to-noise ratios (60 < SNR < 200). The integral length and time scales were calculated via correlation functions across the full range of Reynolds numbers and as function of axial and radial position. The radial dependence of the integral scales was shown to be strongly affected by the increasing intermittency of the turbulence with increasing radial location. Without accounting for local intermittency effects, the integral time scales were overestimated by as much as a factor of three. The results also showed that Taylor's hypothesis, a common Galilean transformation between space and time, properly predicts the functional relationship between the integral length and time scales, but does not allow for a quantitative transformation. A recently proposed "elliptical" model for transformation of correlation functions between space and time was found to be more accurate. The current work demonstrates the accuracy of the elliptical model in turbulent free shear flows for the first time.
520 $a Simultaneous 10 kHz mixture fraction and velocity measurements were performed using two-line spontaneous Raman scattering and particle imaging velocimetry (PIV). Of particular note from a diagnostic standpoint, is that the presence of the PIV seed particles was found to have a negligible influence on the accuracy of the scalar measurements. A qualitative analysis of observed scalar and velocity features show that the majority of the time the axial velocity component and the mixture fraction are highly correlated, but there are distinct periods in which the two fields appear to be relatively uncorrelated or even anti-correlated. Quantitative analysis of statistical metrics including autocorrelation functions, two-point temporal correlation functions, and temporal scalar-velocity cross correlation were performed. The results show that scalar fluctuations and axial velocity fluctuations are highly correlated with a peak correlation coefficient of 0.6 that occurred at zero time lag indicating that the velocity and scalar fluctuations are in phase. Overall, it is concluded that scalar mixing within gas-phase jets is predominantly a passive process and largely controlled by the local axial velocity fluctuations. (Abstract shortened by ProQuest.).
533 $a Electronic reproduction. $b Ann Arbor, Mich. : $c ProQuest, $d 2018
538 $a Mode of access: World Wide Web
650 4 $a Mechanical engineering. $3 557493
655 7 $a Electronic books. $2 local $3 554714
690 $a 0548
710 2 $a ProQuest Information and Learning Co. $3 1178819
710 2 $a The Ohio State University. $b Mechanical Engineering. $3 1148711
773 0 $t Dissertation Abstracts International $g 78-10B(E).
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