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diff --git a/Master/texmf-dist/doc/latex/aiaa/pre2004/demos/paper/smpaiaa.tex b/Master/texmf-dist/doc/latex/aiaa/pre2004/demos/paper/smpaiaa.tex new file mode 100644 index 00000000000..7f6216014c1 --- /dev/null +++ b/Master/texmf-dist/doc/latex/aiaa/pre2004/demos/paper/smpaiaa.tex @@ -0,0 +1,391 @@ +% +% latex2e adocument: smpaiaa.tex +% +% sample AIAA conference paper, journal article, +% journal note, and journal submission +% +% -- bil kleb <10 jan 97> +% + +\documentclass[cover]{aiaa}% options: paper, article, note, + % cover, and/or submit + +% note: until we reach \begin{document}, we're in the `preamble' + +% load items used by the aiaa class: + +% for a conference paper (`paper' option [default]): +\PaperNumber{98--0879} +\PaperNotice{\CopyrightD{1999}} +\CoverFigure{smpfig}% [optional cover figure] +\Conference{{\bfseries 36th AIAA Aerospace Sciences \\ + Meeting and Exhibit} \\ + January~12--15,~1998/Reno,~NV} + +% for journal submission (`submit' option): +\SubmitName{Kleb ET AL.\ (A10659)} + +% for journal simulation (`article' or `note' options): +\JournalName{Journal of Spacecraft and Rockets} +\JournalPage{39} +\JournalIssue{Volume~36, Number~2} +\JournalNotice{Presented as Paper~98--0879 at the AIAA + 36th Aerospace Sciences Meeting, Reno,~NV, + Jan.~12--15,~1998; received Feb.~13,~1998; + revision received Sept.~18,~1998; + accepted for publication Oct.~1,~1998. + \CopyrightD{1999}} + +% specific to journal article: +\ArticleIssue{Vol.~36, No.~2, March--April 1999}% first page +\ArticleHeader{Kleb ET AL.}% subsequent pages + +% specific to journal note: +\NoteHeader{J.Spacecraft, Vol.~36, No.~2: Engineering Notes} + +% load the title, author, and abstract for use with the \maketitle command + +\title{Simulation of an Aerospace Vehicle \\ + Pitch-Over Maneuver} + +\author{ +% +William L.~Kleb% +% + \thanks{Research Engineer, Aerothermodynamics Branch, + Aero- and Gas-Dynamics Division, + Research and Technology Group.} \\ +% + {\itshape NASA Langley Research Center, + Hampton,~VA~23681}\\[5pt] +% +A.~N.~Author% +% + \thanks{Deligent worker, + AIAA member.} +% +\ and Y.~F.~Anotherlongername% +% + \thanksibid{2} \\ % use same footnote as second author +% + {\itshape Someother Affliation, + Atown,~ST~98293} +} + +\abstract{{\em Note: this abstract does not appear when a +journal note simulation is the chosen option.} The objective of +the present work is to summarize the application of unsteady +computational fluid dynamic methods to the problem of predicting +verticle take-off/vertical landing vehicle aerodynamics during an +un-powered pitch-over maneuver. In addition to the +time-dependent simulation of a pitch-over maneuver, a series of +steady solutions at discrete points are also computed for +comparison with wind-tunnel measurements and as a means of +quantifying unsteady effects. As this application represents a +new challenge to unsteady computational fluid dynamics, +observations concerning grid resolution, far-field boundary +placement, temporal resolution, and the suitability of assuming +flow-field symmetry are discussed.} + + +\begin{document} + +\maketitle% create the cover page, title block, and notices + +\section{Nomenclature}% you could have this generated + % automatically via the nomenclature package + +\begin{tabbing} +12345678 \= Reynolds number based on length $s$ \kill +$c$ \> Sound speed, m/s \\ +$M$ \> Mach number \\ +$P$ \> Pressure, Pa \\ +$Re_s$ \> Reynolds number based on length $s$ \\ +$T$ \> Temperature, K \\ +$V$ \> Velocity, m/s \\ +$x,y,z$ \> Cartesian body axes, m \\ +$\alpha$ \> Angle of attack, deg \\ +$\eta$ \> Wall-normal distance, m \\ +$\rho$ \> Density, kg/m$^3$ +\end{tabbing} + +\subsection{Subscripts} +\begin{tabbing} +12345678 \= \kill +$tran$ \> Transition \\ +$w$ \> Wall \\ +$\infty$ \> Freestream +\end{tabbing} + +\subsection{Superscripts} +\begin{tabbing} +12345678 \= \kill +$0$ \> Fiduciary point \\ +$n\!+\!1$ \> Time level +\end{tabbing} + +\section{Introduction} + +\dropword NASA's Access to Space Study\cite{bekey:94ja} +recommends the development of a {\em fully}\ reusable launch +vehicle\cite{dornheim:94awst} to replace the aged Space +Shuttle. {\em The \verb+\dropword+ command created the hanging +capital letter and automatically capitalizes the rest of the +word.} A method of reaching this goal is to develop a vehicle +which does not rely on expendable boosters to reach orbit, a +single-stage-to-orbit vehicle\cite{austin:94ja}. One such +configuration being investigated is a Vertical Take-off and +Vertical Landing (VTVL) concept\cite{austin:94ja}. In one +scenario, the VTVL vehicle, upon completion of its mission in +low-Earth orbit, reenters nose first, decelerates to subsonic +speeds, and then performs a rotation +maneuver\cite{dornheim:95awst,david:95sn,dornheim:95awst2} to +land vertically. + + +Figure~\ref{f:trn2lndg} presents a schematic of the last portion +of a typical VTVL entry. +\begin{figure} + \incfig{smpfig} + \caption{Transition to landing for a VTVL vehicle.} + \label{f:trn2lndg} +\end{figure} +The pitch-over maneuver, which occurs near Mach 0.2, is +characterized by high angle of attack, unsteady, vortical flow. +Accurately predicting vehicle performance during this aerodynamic +pitch-over maneuver is quite challenging. While ground-based +facilities can readily predict the vehicle's aerodynamics at +discrete points during the maneuver, simulating the transient +motion in a wind tunnel is difficult.\cite{oleary:94cp} +Time-dependent Computational Fluid Dynamics (CFD) offers another +means of analyzing the pitch-over maneuver. The majority of work +in unsteady CFD has, however, been restricted to small amplitude, +harmonic variations in angle of attack in support of aeroelastic +flutter predictions.\cite{edwards:92cp} + +The objective of the present work is to summarize the application +of unsteady CFD methods to the problem of predicting VTVL vehicle +aerodynamics during an un-powered pitch-over maneuver (further +details are available in the companion conference +paper\cite{kleb:96cp}). In addition to the time-dependent +simulation of a pitch-over maneuver, a series of steady solutions +at discrete points are also computed for comparison with +wind-tunnel measurements and as a means of quantifying unsteady +effects. As this application represents a new challenge to +unsteady CFD, observations concerning grid resolution, far-field +boundary placement, temporal resolution, and the suitability of +assuming flow-field symmetry are documented in +Ref.~\citen{kleb:96cp}. + +\section{Geometry} + +The vehicle's fore body is an 8 deg half-angle sphere cone with +nose radius equal to 0.3 of the base radius. The aft body, +beginning at the 85 percent fuselage station, is a cylinder with +a partially squared-off cross-section producing flat ``slices'' +extending from the base of the vehicle to approximately the 60 +percent fuselage station. The vehicle has a fineness ratio of +6.4. A complete description of the vehicle geometry modeled has +been given by Woods in Ref.~\citen{woods:95cp}. + +{\em Through the generosity of Karen Bibb, we have a +demonstration of a subfigure situation. Note that with imbedded +labels you can refer to Fig.~\ref{fig:both} as a whole or +specifically, things in Fig.~\ref{fig:first} or +Fig.~\ref{fig:second}.} An early Lockheed-Martin X-33 +configuration was used in the remainder of the examples. The +full vehicle is shown in Fig.~\ref{fig:both}. +\begin{figure} + \begin{subfigmatrix}{1} + \subfigure[\bf First pretty picture.] + {\incfig{smpfig}\label{fig:first}} + \subfigure[\bf Second pretty picture.] + {\incfig{smpfig}\label{fig:second}} + \end{subfigmatrix} + \caption{Temperature distribution comparisons at various wing + semi-span stations as a function of chord. Whuh?} + \label{fig:both} +\end{figure} +This configuration (B1001A) was evaluated during +Phase I of the X-33 program. It has twin vertical tails, fins, +and outboard body flaps. The engines are modeled by the box-shaped +structure on the base. {\em We can also have a ``table'' of two, +or four, or more figures as in Fig.~\ref{fig:four}.} +\begin{figure} + \begin{subfigmatrix}{2} + \subfigure[\bf First pretty picture.] + {\incfig{smpfig}} + \subfigure[\bf Second pretty picture.] + {\incfig{smpfig}} + \subfigure[\bf Second pretty picture, again.] + {\incfig{smpfig}} + \subfigure[\bf First pretty picture, again.] + {\incfig{smpfig}} + \end{subfigmatrix} + \caption{Four small figures in a table-like setting.} + \label{fig:four} +\end{figure} + +\section{Computational Mesh} + +The underlying surface definition database was generated from +structured surface patches obtained using +GRIDGEN\cite{GRIDGEN3D_release}, GridTool\cite{GridTool}, and +simple analytical methods. The unstructured surface and +flow-field grids were then generated using +FELISA\cite{peraire:90cp} and TETMESH.\cite{kennon:92cp} The +coarsest mesh has 32,374 tetrahedra with 6,634 nodes. Additional +meshes are described in Ref.~\citen{kleb:96cp}; however, all the +results shown here are the result of the coarsest meshes. + +Since the flow about symmetric configurations at high angles of attack, +even with zero side-slip, often involve asymmetric, vortex-dominated, +features,\cite{yoshinaga:94cp,cobleigh:94cp,dusing:93cp,fisher:94cp} +two different options for the computational domain were employed: +one modeling the complete vehicle and another modeling only half +of the vehicle, assuming symmetry across the pitch-plane. This +aspect of the study is covered in Ref.~\citen{kleb:96cp}. + +\section{Numerical Method} + +The 3D3U code of Batina\cite{batina:93aij} was used exclusively in this +study. The 3D3U code was originally developed to study harmonically +pitching wings and wing-bodies in transonic flow. The code can +incorporate aeroelastic effects through assumed mode shapes, coupled +with a deforming mesh via the linear spring analogy. + +The following defaults were used for the computed results in this +study: Roe's flux-difference splitting, an eigenvalue limiter +threshold value of 0.3, second-order flux reconstruction using a +$\kappa$ of 0.5, and Gauss-Seidel implicit time integration with +a CFL number of one million. + +\section{Maneuver Definition} + +The pitch schedule chosen for this study is the first half of a +sine function. Initially, the vehicle is in steady flight at +17.5 degrees angle of attack, Mach 0.2. At time zero, the +vehicle begins the pitch-over maneuver, reaching a maximum pitch +rate exactly half-way through the maneuver and finishing at a 180 +deg angle of attack. For this study, the time to complete the +maneuver was chosen as 90 seconds, giving a maximum rotation rate +of 3.1 deg per second halfway through the maneuver. For +simplicity, it is assumed that the free-stream Mach number +remains constant throughout the maneuver. + +{\em Sticking in a table for guidance (see Table~\ref{tab:sample}).} +\begin{table}[htbp] + \begin{center} + \caption{A sample table} + \begin{tabular}{ccc} \hline\hline + \multicolumn{2}{c}{Header 1} & Header 2 \\ \hline + a & b & c \\ + d & e & f \\ \hline\hline + \end{tabular} + \label{tab:sample} + \end{center} +\end{table} +Normally there would be text following the table, so that it +is not left ``hanging'' into the next section. + +\section{Results} + +The main results are presented in two stages which are followed +by comments on flow asymmetries for both steady and unsteady +flows. The first stage is computed steady data as it compares to +experimental results. while the second is a comparison of steady +to unsteady data. + +\subsection{Steady Flow} + +As a baseline to examine the unsteady effects of the pitch-over +maneuver itself, steady flow at selected angles of attack were +computed. Figure~\ref{f:expcomp} shows a comparison of the +normal force coefficient with the experimental data of +Woods\cite{woods:95cp} for angles of attack from 0 to 60 deg. +\begin{figure} + \incfig{smpfig} + \caption{Comparison of steady normal force coefficient as a + function of angle of attack with experimental data of + Woods\protect{\cite{woods:95cp}}} + \label{f:expcomp} +\end{figure} +The computed results agree well (within 20 percent) at small angles of attack, +and diverge from the experimental results as the angle +of attack increases largely due to the position of the lee-side +separation line---a viscous phenomenon. +Since the computed results are modeling inviscid +flow, the only mechanism for flow separation is the numerical +dissipation in the scheme. Thus, the exact location of the computed +separation line is highly grid and scheme dependent. Compounding +this is the fact that the lee-side separation line nearly +encompasses the length of the vehicle; and thus, a slight +deviation can make a large difference in the integrated coefficients. + +\subsection{Unsteady Flow} + +Figure~\ref{f:aerocomp} compares the normal force coefficient of +both the steady and unsteady calculations. +\begin{figure*} + \incfig{smpfig} + \caption{Comparison of steady and unsteady normal force + coefficients as a function of angle of attack. {\em Example + of a figure that spans both columns. The danger is that the + figure numbering may be out of order since the single-column + float and double-column float counters are not connected when + it comes to determining placement order. You can correct this + known ``feature'' of \LaTeX{} by using the \texttt{fix2col} package.}} + \label{f:aerocomp} +\end{figure*} +The solid line represents the unsteady results and the symbols +are the steady-flow results. Readily discernible is the fact +that the steady and unsteady results are significantly different. +The time-dependent results have the time lag behavior expected +for moderately unsteady flow: showing the same general +qualitative trend throughout the angle-of-attack range, but with +the unsteady results lagging behind the steady results. Other +aerodynamic coefficients show similar +differences.\cite{kleb:96cp} + +\subsection{Flow Asymmetry} + +As documented in Ref.~\citen{kleb:96cp}, no appreciable +asymmetries were found for the steady flow cases computed +although they were present in the experimental data of +Woods\cite{woods:95cp}. However, for the unsteady case, +asymmetric flow is apparent as shown in Figure{f:uasym}. +\begin{figure}[t] + \incfig{smpfig} + \caption{Unsteady flow asymmetry: side force coefficient as a + function of angle of attack.} + \label{f:uasym} +\end{figure} +This figure shows the appearance of a non-zero side-force similar +to that reported for {\em steady} flow by Woods\cite{woods:95cp}. +The most significant manifestations of the asymmetries occur in +the 90 to 135 deg angle-of-attack range. + +\section{Concluding Remarks} + +The objective of the present work was to focus an unsteady CFD +method on the prediction of VTVL vehicle aerodynamics during a +pitch-over maneuver. This was accomplished through the use of +the inviscid 3D3U code\cite{batina:93aij} A series of steady +solutions at discrete points in the maneuver were computed and it +was shown that, even for the unrealistically slow pitch-over rate +studied, unsteady effects were large. More importantly, the +rotation maneuver creates flow asymmetries which lead to side +forces not apparent for the steady cases. + +As this is an exploratory study, there is certainly room for +future work. The following is just a handful of extensions which +would be necessary to create an effective design tool: +incorporating viscous effects, allowing movable control surfaces, +coupling a six-degree-of-freedom rigid body dynamics solver, +adding control law, and incorporating an adaptive grid +capability. + +\bibliography{smpbtx} +\bibliographystyle{aiaa} + +\end{document} |