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\titleConf{12th Thermal and Fluids Engineering Conference (TFEC)\\
March, 14-17, 2027}
\city{In person at Southern Methodist University, Dallas, TX, USA\\
And partially online virtual via Zoom and Whova}







\begin{document}
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\PaperNumber{TFEC-2027-xxxxx}
\title{Proceedings Title}
%For at least  authors with different addresses, use instead the following commands
\corrauthor[1]{First A. Author}
\author[1]{Second B. Author, Jr.}
\author[2]{Third Author}
\author[2]{Fourth C. Author}
\corremail{f.author@affiliation.com}
% \doi{http://dx.doi.org/10.1615/TFE2020C.XXX.XXX}
\address[1]{Business or Academic Affiliation 1, City, State, Zip Code}
\address[2]{Business or Academic Affiliation 2, City, Province, Zip Code, Country}
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%\author{Second B. Author, Jr.}
%\address{Department of Chemistry and Courant, Institute of Mathematical Sciences, New York, NY 10012, USA}
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\abstract{This guide has been prepared for authors of papers to be presented at the 12th Thermal and Fluids Engineering Conference (TFEC), March, 14-17, 2027. The abstract summarizes key findings in the paper and should be a paragraph no more than 250 words.
 The abstract summarizes key findings in the paper and should be a paragraph no more than 250 words.
 The abstract summarizes key findings in the paper and should be a paragraph no more than 250 words.
 The abstract summarizes key findings in the paper and should be a paragraph no more than 250 words.
 The abstract summarizes key findings in the paper and should be a paragraph no more than 250 words.
}

\keywords{select up to 10 key terms for a search on
your document}

\maketitle


\begin{table}[!h]
\centering\begin{tabular}
{@{}p{0.5\textwidth}  p{0.5\textwidth}@{}} &\\[-2pt]
\multicolumn{2}{c}{\large{\bf NOMENCLATURE}}  \\&\\[-5pt]
\begin{tabular}
{@{}l l l@{}}
Be	&dimensionless variable		&( - )\\
$C$	&second variable			&(s$^2$)\\
\end{tabular}&
\begin{tabular}
{@{}l l l@{}}
$Q_A$	&third variable			&(kJ)\\
$w_x$	&fourth variable			&(m$^2$/s)\\
\end{tabular}\\[-5pt]&\\
\end{tabular}%\vspace{-30pt}
\end{table}


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\section{Introduction}
Heat is difficult to measure, even at macroscales! At macroscales, key
quantities of interest for heat transfer are temperature, heat flux, and
thermophysical properties such as thermal conductivity, specific heat, etc.
Conductive and convective heat transfer at macroscale are usually governed
by diffusion processes because heat carriers (molecules, electrons, phonons,
etc.) in these processes have short mean free paths and short wavelengths.
In micro- and nanostructures, however, the mean free paths and even
wavelengths of heat carriers become comparable or longer than the
characteristic length involved in the transport process. Heat transfer can no longer be
described by established theories applicable to macroscale. It is precisely
these deviations from continuum that have drawn significant interests from
scientific communities to understand micro-/nanoscale heat transfer.
Such understandings have potential impacts over a wide range of
applications, from microelectronics to energy conversion. Experimentally
probing heat transfer in micro-/nanostructures is essential for scientific
and technological endeavors, and significant progress has been made over the
last two decades. This volume aims to provide a summary of the advances made
in probing micro-/nanoscale heat transfer.
\begin{equation}
  R(E) = \frac{\kappa}{2\eta} \int_{\Omega}\left( \nabla{E}\cdot\nabla{E} +
  \varepsilon \right)^{\eta} \, d\Omega
\end{equation}



In many gasoline direct injection (GDI) engines hollow cone sprays generated by swirl or outwardly opening injectors are applied. In this study the spray of an outwardly opening injector is investigated. According to the geometrical shape of an outwardly opening pintle nozzle the fuel exits from an annular gap. Previous investigations have already shown that the hollow cone spray leaving this nozzle is composed of many single strings instead of a continuous conical sheet.

The dependency of the string spacing on boundary conditions has been described by different authors. \cite{Arcoumanis2008} stated that the string spacing is a function of the fuel rate, while \cite{Befrui2008} and \cite{Reckers2008} found out that the injection pressure has some influence on the string structure. Additionally, \cite{Nouri2007} mentioned that velocity affects the string formation, while the effect of ambient pressure can be neglected \citep{Nouri2007b}.

\begin{table}[!t]
\centering
\caption{Injected fuel mass}\vspace{-10pt}
\begin{tabular}{|ccc|}
\hline
\textbf{injection duration}   & \textbf{injection pressure} & \textbf{fuel mass}  \\
$\Delta t$ [$\mu$s] & [MPa] & [mg] \\
\hline
300 & 1 & 1.7 \\
300 & 2 & 3.0 \\
300 & 3 & 4.0 \\
300 & 4 & 4.7 \\
300 & 5 & 5.4 \\
300 & 6 & 6.0 \\
300 & 7 & 6.5 \\
300 & 8 & 6.9 \\
300 & 9 & 7.2 \\
300 & 10 & 7.6 \\
300 & 11 & 7.7 \\
300 & 12 & 8.0 \\
\hline
100 & 10 & 0.6 \\
200 & 10 & 4.3 \\
400 & 10 & 10.3 \\
\hline
\end{tabular}
\end{table}

\begin{figure}[!b]
	\centering
  \includegraphics[width=7cm]{Fig1.eps}
\caption{Visualization setup.}
\label{fig:VisSetup}
\end{figure}

According to \cite{Gavaises2006} and \cite{Reckers2008} the fluid flowing radially through the gap between pintle and seat exhibits an enlargement of the flow passage cross-sectional area, and thus flow separation inside the nozzle and buildup of air pockets at the nozzle exit can be observed \citep{Befrui2008}. This causes a two-phase flow inside the nozzle that is responsible for the stringy structure at the nozzle exit \citep{Arcoumanis2008}.
Investigations with a large-scale transparent nozzle \citep{Nouri2007} show that the surface structure cannot be the only reason for the strings, since the strings could be observed for the large scale nozzle as well as for the original nozzle although the corresponding relative surface roughness is quite different.
Cavitation seems not to be responsible for the flow structure, even though it may enforce or influence the string formation. \cite{Befrui2008} justified this statement with a volume-of-fluid-simulation that excludes the modeling of cavitation but shows the typical string structure. Additionally, \cite{Gavaises2006} observed strings both for cavitating and noncavitating nozzles.

A detailed study of the influences of different injection conditions on the string-like structure has not been accomplished so far. Therefore, the goal of this investigation is to give a detailed comparison of the impact of injection conditions on spray structure at the nozzle exit. Visualization measurements with a far-field microscope are applied to identify the interspacing of the string structure at varying injection pressures and injection durations. Additionally, laser correlation velocimetry (LCV) is used to investigate the velocity of the strings, and to examine possible correlations between the string structure and the spray velocity at the exit.

These results are needed to understand the phenomena in order to   validate numerical simulations.

\subsection{Measurement Sensitivity, Uncertainty, Reproducibility, and
Calibration}


Heat flux cross small structures such as nanowires is very tiny, and
high-sensitivity heat flux meters are needed for thermal measurements.
Similar to macroscale heat flux measurements, nanoscale heat flux
measurements usually require knowing temperature differences between two
points and thermal resistance between the same points, from which the heat
flux can be calculated. The key for small heat flux measurements is to
create structures with large thermal resistance values between the two
temperature measurements points.


\subsubsection*{Suspended structures.}

Suspended structures used for nanowire
thermal conductivity measurements serve as a good example.
From the entire volume, it is clear that significant progress has been made
in experimental techniques to probe nanoscale heat transfer phenomena, and
the experimental results have led to new understandings of heat transfer
physics, generated new challenges, and opened new opportunities. From my own
perspective, the following are some significant challenges.


\section{Conclusions}

Significant progress has been made in terms of tailoring the radiative
properties with micro-/nanost\-ructured materials. Rapid developments have
been made in fabricating periodic gratings and nanostructured periodic
arrays of metal materials over thin films and multilayers. Magnetic
responses have been demonstrated in the infrared and even visible spectral
regions. Further research is needed to understand the coupling mechanisms
between various modes and localized surface plasmons. While FDTD and RCWA
can be used to calculate the radiative properties for engineered surfaces
with micro-/nanostructures, faster computational algorithms are needed with
complicated structures to assist the design for specific applications. The
optical constants are often different in the nanostructured materials as
compared with the bulk solid. Furthermore, for high-temperature
applications, the chemical and thermal stability must be considered, as well
as the size- and temperature-dependent optical constants of the materials.

Aligned metallic nanowires may exhibit unique optical and thermal radiative
properties due to the surface-enhanced absorption and scattering,
anisotropic dielectric function, and magnetic resonance (between parallel
wires), and may be applied to diffraction optics as well as IR polarizers
and in the control of optical and radiative properties. Detailed models
considering both surface scattering and volume scattering will allow better
understanding of the radiative transfer in these inhomogeneous structures.
Methods for fabricating more uniform structures in large areas with a high
yield are still needed. Measurements at longer wavelengths, i.e., mid- to
far-IR, will help in understanding the effective medium behavior as well as
the magnetic response.

VACNT arrays show great promise for radiometric applications as nearly
perfect absorbers and emitters in a broad spectral region. EMT appears to be
able to describe the visible and infrared properties of CNT arrays
reasonably well. Specular and diffuse black materials made of SWCNTs or
MWCNTs should be valuable for space-borne radiometric systems, high-power
laser radiometers, absolute cryogenic radiometers, and infrared calibration
facilities. The chemical stability and mechanical rigidity of these
structures also need to be further investigated. A challenge that exists in
the materials growth process is how to control the growth conditions so that
arrays with a controllable degree of alignment and surface morphology can be
reproduced. In terms of optical properties of CNTs, quantitative
understanding of the anisotropic optical behaviors should be pursued. There
is a need to investigate the polarization-dependent reflectance and
transmittance at oblique incidence.

\textbf{Submission Deadline:} Full paper PDF should be submitted before \textbf{December 06, 2026}.



\acknowledgements

This work is supported by U.S. Department of Energy, Office of Science,
Office of Basic Energy Sciences under Award No. DE-FG02-02ER45977.






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