Eric Jumper

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Air Force Academy Aeronautics Digest - Fall 1979

AIR FORCE ACADEMY Aeronautics Digest- Spring/Summer 1982

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Theoretical Investigation of Dynamic Stall Using a Momentum Integral Method

: An analytical study into the gust response of an airfoil is presented. The momentum-integral eq... more : An analytical study into the gust response of an airfoil is presented. The momentum-integral equation for steady flow is extended into the airfoil that experiences a constant-rate-of-change of angle-of-attack gust. The von Karman-Pohlhausen method of integration is successfully modified to incorporate the additional transient flow terms; the equation of closure necessary to do this is also presented. Finally, computation of the flow about a Joukowski airfoil using the new equations is performed and the results are presented and discussed. It is shown that these results are in agreement with existing experimental data.

Air Force Academy Aeronautics Digest. Fall 1978

: This digest covers unclassified research in aeronautics performed at the United States Air Forc... more : This digest covers unclassified research in aeronautics performed at the United States Air Force Academy during the six months ending 1 January 1979. This report includes individual technical papers in the specific areas of aerodynamics, fluid mechanics, experimental instrumentation, engineering education and thermodynamics and heat transfer. (Author)

Air Force Academy Aeronautics Digest - Fall/Winter 1981

: Contents: Experimental Documentation of the Lifting Surface Wakes of a Canard and Forward-Swept... more : Contents: Experimental Documentation of the Lifting Surface Wakes of a Canard and Forward-Swept Wind Configuration; Experimental Flow Field Measurements of Three-Dimensional Square Cross-Section Missiles at Moderate Angles of Attack; What Makes the Aircraft Gas Turbine Engine so Good at Altitude; Determination of the Frequency Response Characteristics of a Redesigned Seven-Hole Pressure Probe; The Aeronautics Department and Core Courses at the United States Air Force Academy; and Some Aeronautical Experiments by Wilbur Wright; and The Engineer's Bookshelf.

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Air Force Academy Aeronautics Digest. Spring 1979

: This digest covers unclassified research in aeronautics performed at the United States Air Forc... more : This digest covers unclassified research in aeronautics performed at the United States Air Force Academy during the six months ending 1 July 1979. This report includes individual technical papers in the specific areas of aerodynamics, fluid mechanics, experimental instrumentation, engineering education and thermodynamics and heat transfer. (Author)

Waves Elicited from the Stator Row Downstream of a @'an

Fluid dynamic issues in continuous wave short wavelength chemical lasers

This paper addresses fluid dynamic issues of concern in the design and development of Continuous ... more This paper addresses fluid dynamic issues of concern in the design and development of Continuous Wave (CW) Short Wavelength Chemical Lasers (SWCLs). Short Wavelength Chemical Laser technology is in its research stage and SWCL concepts are in their evolving mode. Researchers are presently addressing candidate chemical systems and activation concepts. Since these lasers will be flowing systems, it is necessary to discuss both the probable fluid dynamics issues, because of the inherent complexities fluid dynamicist can support this activity. In addition to addressing the SWCL fluid dynamic issues, this paper will review past fluid dynamic activities in high energy lasers and discuss additional research still required. This paper will also address the various levels of fluid dynamic modeling and how these models can be applied in studying the fluid dynamics of Short Wavelength Chemical Lasers. Where it is felt that specific fluid methodologies are not available, but are required in orde...

Transient analysis of a laser supported detonation wave using Whitham’s rule

The Physics of Fluids, 1978

Analysis is made of a laser supported detonation wave using Whitham’s rule. The C+ characteristic... more Analysis is made of a laser supported detonation wave using Whitham’s rule. The C+ characteristic is developed for absorption of laser energy immediately behind a shock wave. The characteristic is then coupled with the Rankine-Hugoniot equations relating conditions across the shock. In this way an equation for predicting the transient shock strength is obtained. The result is compared to experiment and to steady state laser supported detonation theory. The result of this comparison is that the derived equation does duplicate the transient response of the experiment and (when allowed to run to steady state) it does agree with many of the characteristics of the steady state theory.

Model for oxygen recombination on silicon-dioxide surfaces. II - Implications toward reentry heating

30th Aerospace Sciences Meeting and Exhibit, 1992

This paper briefly reviews the model for recombination of oxygen on a silicon-dioxide surface pre... more This paper briefly reviews the model for recombination of oxygen on a silicon-dioxide surface presented in detail in a previous paper. New data supporting the model is also presented. The ramifications of the model toward the production of excited molecular oxygen is examined as it pertains to surface heating. A reentry simulation is given and compared to STS-2 reentry data, and conclusions are drawn as to the implications of the recombination model toward reentry heating. A possible buffering of the heating above a critical temperature associated with the physics of the model is also discussed.

Theoretical and Numerical Study of Asymmetric Unsteady Lex and Slender-Wing Vortices Including Breakdown

Abstract : The following final report documents the accomplishments made under AFOSR Grant F49620... more Abstract : The following final report documents the accomplishments made under AFOSR Grant F49620-92-J-9105 for the period starting January 1, 1992 and ending September 30, 1995. During this time, progress was made in better understanding the spiral vortex breakdown phenomenon. A theoretical model of vortex breakdown was developed illustrating the self-induced cause-and-effect nature of the breakdown spiral in sustaining its geometry in an adverse pressure field. From this study a geometric compatibility condition was discovered in the form of a non-dimensional circulation strength. Experiments were conducted to experimentally confirm this geometric compatibility condition. An isolated vortex was subjected to two breakdown-inducing flowfields; the first consisted of a flow obstruction, and the second consisted of a pair of counter-rotating cylinders. The geometric compatibility condition was found to exist for the resulting spiral vortex breakdown from both of the experiments. Three papers were written and presented on this study at several AIAA Applied Aerodynamics conferences, and a journal paper is currently under review. Also, an abstract was submitted in October, 1995 for an AIAA Applied Aerodynamics conference in 1996.

Recombination of Oxygen and Nitrogen on Silica-Based Thermal Protection Surfaces: Mechanism and Implications

Springer eBooks, 1996

A number of papers, see for example [1], have pointed out the importance of being able to model t... more A number of papers, see for example [1], have pointed out the importance of being able to model the catalytic recombination of oxygen and nitrogen on silica-based materials because of the role that these reactions play in re-entry heating. Because the energies of molecular oxygen and nitrogen are less than that of two atoms of oxygen and nitrogen, respectively, when these species recombine, the excess energy can be transferred directly to the surface, representing an additional heat load [2]. Silicon dioxide is the principal material making up the Space Shuttle thermal-protection-tile surface; to be more precise, the surface is a borosilicate reaction-cured glass (RCG) [3]. This paper describes a kinetic approach to modeling the recombination of oxygen and nitrogen on Reaction-Cured Glass (RCG). The paper is meant to present only a brief review of these models; more detail on these models can be found in [4–7].

A multi temporal trainable delay neural network

Proceedings of 1994 IEEE International Conference on Neural Networks (ICNN'94), 1994

Neural networks have been used for analysis of temporally related patterns. Methods used include ... more Neural networks have been used for analysis of temporally related patterns. Methods used include the encoding of temporal data for input to static networks, backpropagation through time, avalanche filters, recursive networks and temporal difference learning. Each of these methods attempt to learn temporal relationships through the use of varying amplification weights coupled with a constant periodic sampling of input signals. This paper presents a method of using delays rather than amplifications to encode temporal relationships directly into the network. This method improves memory usage by the network during simulation as well as reducing the required size of the network for temporal analysis.<<ETX>>

Model for oxygen recombination on reaction-cured glass

Journal of Thermophysics and Heat Transfer, 1994

This article briefly reviews the model for recombination of oxygen on a silicon-dioxide surface p... more This article briefly reviews the model for recombination of oxygen on a silicon-dioxide surface presented in detail in a previous paper. Data for oxygen recombination on reaction-cure d glass (RCG), a silicon-dioxid ebased material, is presented and compared with the Si-O2 recombination model. The model is modified slightly to better represent the oxygen-RCG system, but the essential feature of the model, the participation of the oxygen of the surface matrix itself, remains unchanged. The ramifications of the model toward the production of excited molecular oxygen is examined as it may pertain to surface heating during a re-entry. Data indicating that the predicted production of singlet-delta oxygen, and no higher-electronic-state oxygen is given in support of the model.

Mechanisms for thermally enhanced target coupling by repetitively pulsed lasers

Journal of Thermophysics and Heat Transfer, 1987

Dynamic Leading-Edge Flap Scheduling

Journal of Aircraft, 1997

ABSTRACT This paper reports on an experimental determination of a leading-edge flap schedule used... more ABSTRACT This paper reports on an experimental determination of a leading-edge flap schedule used to maintain attached flow during arbitrary. dynamic pitch motions of a NACA 0009 airfoil, The airfoil could be made to dynamically pitch about ifs midchord, and was equipped with a 20% leading-edge flap and 27% trailing-edge flap, both of which could be independently and dynamically deflected, Airfoil normal force histories were measured during dynamic pitch and/or flap motions (either or both flaps) by integrating the tints histories of pressure measurements taken at 28 locations enveloping the airfoil, A static leading-edge flap schedule was determined using both flow visualization and surface pressure surveys; it was found that attached flow could be maintained by keeping the leading-edge flap aligned with the oncoming flow. Application of the statically determined leading-edge flap schedule during dynamic airfoil or combined airfoil and trailing-edge flap motions shelved that this simple leading-edge nap schedule worked even more robustly during dynamic experiments. Finally, the leading-edge flap schedule was applied to an unsteady lift-control experiment, in which trailing-edge flap Notions computed using a control algorithm were used to control the unsteady lift on the airfoil during large dynamic pitch motions. These experiments showed that satisfactory lift control was possible when the leading-edge nap schedule nas implemented, and that no modification to the lift-control algorithm was necessary to account for the leading-edge nap motions.

Wave drag prediction using a simplified supersonic area rule

Journal of Aircraft, 1983

Simple theories of dynamic stall that are helpful in interpreting computational results

Computer Physics Communications, 1991

Abstract This paper briefly reviews the phenomena of dynamic stall and comments on some of the th... more Abstract This paper briefly reviews the phenomena of dynamic stall and comments on some of the theoretical work performed to help understand why the phenomena occurs for two-dimensional flow past an airfoil undergoing a pitching motion. A first look at how these understandings might be extended to three-dimensional flow fields past finite-span wings is also presented. In particular, a simple theory is developed that provides a rationale for why the experimental results from studies of finite-span wings undergoing dynamic stall closely resemble the dynamic-stall results for two-dimensional airfoils, while steady-flow results from finite-span wing studies are so dissimilar from those for two-dimensional airfoils.

Air Force Academy aeronautics digest: Spring/summer 1981[Final Report]

Air Force Academy aeronautics digest: Spring/summer 1981[Final Report]. AMHIGGINS, FM JONAS, EJ J... more

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