Aerospace Engineering Commons^™

Assessment Of Sting Effect On X-31 Aircraft Model Using Cfd, Adam Jirásek, Russell M. Cummings

Aerospace Engineering

The article describes the computational evaluation of the effect a belly mounted sting on the aerodynamics characteristics of an X-31 wind tunnel model. The investigation includes results of steady and time-dependent CFD analysis of the X-31 model with and without sting. The values of the steady lift and pitching moment coefficients as well as the pitching moment of model undergoing a manuever are compared to each other and to the wind tunnel data. The results of this analysis show the detrimental effect of sting on stability of the vortical structure above the wing as well as a substantial increase of …

Overview Of Recent Circulation Control Modeling Activities At Cal Poly, David D. Marshall, Kristina K. Jameson

Aerospace Engineering

This paper provides an overview of the Circulation Control modeling research that has been performed, and is still ongoing, at Cal Poly, San Luis Obispo. This work started in 2005 with the interest of applying Circulation Control technologies to advanced aircraft designs. After the initial investigations into this, it was apparent that there was a long history of experimental work in this area to build on, but a number of deficiencies existed in the modeling capabilities. For Circulation Control enabled aircraft, these included: few available tools to accurately model the takeoff and landing performance, the limitations in the standard regulations …

Improved Methodologies For Maneuver Design Of Aircraft Stability And Control Simulations, Adam Jirásek, Tiger L. Jeans, Mathew Martenson, Russell M. Cummings, Keith Bergeron

Aerospace Engineering

With many modern fighter aircraft experiencing unpredicted flight dynamics during flight tests, recent research has focused on developing methodologies for incorporating computational fluid dynamics into the aircraft development process. The goal of this approach is to identify configurations susceptible to stability and control issues early in the design process. Previous research has primarily focused on full aircraft configurations, however, to increase the rate of development the current study focused on a two-dimensional NACA0012 airfoil. The two-dimensional NACA0012 airfoil has the advantage of reducing the computational cost by orders of magnitude compared to full scale aircraft simulations, while still providing complicated …

Parameter Estimation Of Fundamental Technical Aircraft Information Applied To Aircraft Performance, Mike Vallone, Robert A. Mcdonald

Aerospace Engineering

Inverse problems can be applied to aircraft in many areas. One of the disciplines within the aerospace industry with the most openly published data is in the area of aircraft performance. Many aircraft manufacturers publish performance claims, flight manuals and Standard Aircraft Characteristic (SAC) charts without any mention of the more fundamental technical information such as C_D0. With accurate tools, generalized aircraft models and a few curve-fitting techniques, it is possible to evaluate vehicle performance and estimate these technical parameters.

With this goal a program has been written in Matlab to calculate the fundamental information behind a …

Designing A Green Aircraft: Cal Poly's 2009 Undergraduate Aircraft Designs, Robert A. Mcdonald, Bruce Wright

Aerospace Engineering

The Cal Poly senior design class submitted six designs this year in response to the 2009 Undergraduate Team Aircraft Design Competition. This paper summarizes our experiences teaching design through this RFP and brings the student's insights together.

Conceptual Design Of An Environmentally Responsible 150-Passenger Commercial Aircraft, Natalie R. Smith, Bryan Blessing, James Dixon, Allen Mackey, Gregory Mckenzie, Robert A. Mcdonald, Bruce Wright

Aerospace Engineering

Verde is an environmentally responsible commercial transport seating 150 dual-class passengers, designed in response to the 2008-2009 Request for Proposal from the American Institute of Aeronautics and Astronautics Undergraduate Team Aircraft Design Competition. While the airline industry faces increasing pressures from the cost of fuel and the responsibility of environmental impact, the next generation of this aircraft class must operate more efficiently and address those environmental needs. Therefore, all design decisions for Verde focused first on reducing fuel burn, second on reducing emissions, then noise, and finally on maintaining flyaway cost, airport integration, and passenger comfort. The final design utilizes …

Lift Superposition And Aerodynamic Twist Optimization For Achieving Desired Lift Distributions, Kevin A. Lane, David D. Marshall, Robert A. Mcdonald

Aerospace Engineering

A method for achieving an arbitrary lift distribution with an arbitrary planform is presented. This is accomplished through optimizing aerodynamic twist for a given number of either known airfoils or airfoils to be designed. The spanwise locations of these airfoils are optimized to get as close to the desired lift distribution as possible. Airfoils are linearly interpolated between these points. After aerodynamic twist, the planform is twisted geometrically using radial basis functions to model the twist distribution. The aerodynamic influence of each twist distribution is determined and all are superimposed to determine the function weights of each twist function, yielding …

A Three Dimensional Vortex Particle-Panel Method For Modeling Propulsion-Airframe Interaction, Jacob S. Calabretta, Robert A. Mcdonald

Aerospace Engineering

The panel code has been a pivotal tool for aerodynamic simulations for decades, today providing users with quick solutions without the necessity of a volume grid. Unfortunately, the panel code also carries with it some inherent shortcomings when compared with other methods. One such weakness is its inability to account for any work done on or by the system in question. This paper proposes a method to address this issue by combining vortex particles with a panel code, and using them to model the work effects of a propeller or engine. While the proposed model is still a work in …

Computational And Experimental Comparison Of A Powered Lift, Upper Surface Blowing Configuration, Jay Marcos, David D. Marshall

Aerospace Engineering

This paper demonstrates the use of CFD as a validation tool for wind tunnel data on 2D high lift airfoil with a 3D engine performed by Georgia Tech Research Institute. Results of this validation will assist in determining the appropriate turbulence models, boundary conditions, mesh characteristics and other CFD modeling techniques necessary to capture the complicated flow physics associated with the coupling of circulation control wings and engine exhaust flows. It was found that grid issues and the two-equation turbulence model, k-ε, over predicted lift as blowing momentum increases even with the additional complexity of having an over the wing …

Design And Performance Of Circulation Control Flap Systems, Rory M. Golden, David D. Marshall

Aerospace Engineering

The design of circulation control (CC) dual radius flap systems were investigated to characterize the parameters that make up the flap surface to offer further knowledge into the CC field of study. Multiple dual radius flap geometries, along with variants, were developed by varying specific flap parameters from a baseline configuration that had previously developed. The aerodynamics of the different flap geometries were analyzed using two-dimensional CFD. This research will explore the design of CC pneumatic flap systems to improve the performance of existing CC flap configurations, and provide insight into the characteristics of the CC flap geometry.

Towards Efficient Viscous Modeling Based On Cartesian Methods For Automated Flow Simulation, Patrick Hu, Hongwu Zhao, Ramji Kamakoti, Nagendra Dittakavi, Liping Xue, Kan Ni, Shaolin Mao, David D. Marshall, Michael Aftosmis

Aerospace Engineering

The advanced Computational Fluid Dynamics (CFD) techniques that address the current limitations of Cartesian-based Navier-Stokes CFD schemes are explored in current investigation. Three promising methods of implementing improved wall boundary conditions are applied: (1) the enhanced diamond path stencil approach, (2) the reformulated extended extrapolation boundary condition, and (3) the ghost cell method. Several initial testing cases have been conducted with all these three boundary conditions, including the flow past a circular cylinder, flow past a flat plate at different inclined angles and flow past an AGARD RAE2822 airfoil. All the results show the effectiveness of these boundary conditions in …

Inverse Airfoil Design Utilizing Cst Parameterization, Kevin A. Lane, David D. Marshall

Aerospace Engineering

An inverse airfoil design process is presented that makes use of the CST parameterization method. The CST method is very powerful in that it can easily represent any airfoil shape within the entire design space of smooth airfoils. This makes it an ideal modeling technique for an inverse design process because accurate airfoil geometry treatment is required. The downfall of some inverse design processes is that they do not accurately handle the leading edge region due to large flow gradients and high curvature distributions. One way to account for this is by representing airfoils with smooth analytic functions, such as …

Assessing The V2-F Turbulence Models For Circulation Control Applications, Travis M. Storm, David D. Marshall

Aerospace Engineering

This paper explores the applicability of several variations of the v²-f turbulence model to circulation control flows. The effects of modifying the model to capture nonlinear eddy viscosity effects and streamline curvature effects are assessed. Results indicate that the v²-f turbulence model is capable producing more physically accurate results for circulation control flow fields than common modern turbulence modeling techniques.

Mixi Thruster Tungsten And Thoriated Tungsten Testing, Jesse R. Miller

Aerospace Engineering

The purpose of this project is to build and evaluate a tungsten filament cathode for the 3-cm Miniature Xenon Ion (MiXI) thruster. The filament is to be used for future tests within the CP 3-cm MiXI and thoriated tungsten is to be examined as a possible alternative. No testing of these filaments was conducted, but the preparatory work has been conducted for future testing.

Effects Of Delamination On Composite Sandwich Structures Under Static And Fatigue Loading, Eugene Everett Eswonia

Master's Theses

This thesis will present the experimental and numerical analysis of composite sandwich structures under monotonic and fatigue loading. The sandwich skins were made of fiberglass and the core used was a closed cell PVC foam. Initial delaminations were introduced into the sandwich structures during manufacturing to see the effect of delamination size on the ultimate strength and monotonic fracture. Fiberglass rods, called shear keys, added to the foam core to determine whether or not they increased the strength of the test specimens. Furthermore, shear key locations were also varied and their effects noted. The fixed rate static behavior for all …

Aerodynamic Performance Enhancement Of A Naca 66–206 Airfoil Using Supersonic Channel Airfoil Design, David Michael Giles

Master's Theses

Supersonic channel airfoil design techniques have been shown to significantly reduce drag in high-speed flows over diamond shaped airfoils by Ruffin and colleagues. The effect of applying these techniques to a NACA 66-206 airfoil is presented. The design domain entails channel heights of 8-16.6% thickness-to-chord and speeds from Mach 1.5-3.0. Numerical simulations show an increase in the lift-to-drag ratio for airfoils at Mach 2.5 at a 35,000-ft altitude with a 12% channel height geometry showing a benefit of 17.2% at 6-deg angle of attack and a sharp channel leading edge. Wave drag is significantly reduced while viscous forces are slightly …

Numerical Solutions For The Cawapi Configuration On Unstructured Grids At Usafa, United States, Scott A. Morton, David R. Mcdaniel, Russell M. Cummings

Aerospace Engineering

No abstract provided.

Lessons Learned From The Numerical Investigations On The Vfe-2 Configuration, Willy Fritz, Russell M. Cummings

Aerospace Engineering

The Second International Vortex Flow Experiment provided a variety of experimental data for a 65° delta wing with sharp and blunt/rounded leading edges. Flow measurements including forces and moments, surface pressures, Pressure Sensitive Paint measurements, and off-surface flow variables from Particle Image Velocimetry were made available for comparisons with computational simulations. A number of test cases were chosen for simulation by seven numerical groups, and a summary of their results is presented here. The ability of computational fluid dynamics to predict such flow features as the dual primary vortex system found on the blunt leading edge configuration and a shock/vortex …

Shock Effects On Delta Wing Vortex Breakdown, Lucy A. Schiavetta, Okko J. Boelens, Simone Crippa, Russell M. Cummings, Willy Fritz, Ken J. Badcock

Aerospace Engineering

It has been observed that delta wings placed in a transonic freestream can experience a sudden movement of the vortex breakdown location as the angle of incidence is increased. The chapter reports on the use Computational Fluid Dynamics (CFD) to examine this behaviour in detail. The study shows that a shock-vortex interaction is responsible. The balance of the vortex strength and axial flow, and the shock strength, is examined to provide an explanation of the sensitivity of the breakdown location. Limited experimental data is available to supplement the CFD results in certain key respects, and the ideal synergy between CFD …

Numerical Solutions For The Vfe-2 Configuration On Unstructured Grids At Usafa, United States, Russell M. Cummings, Andreas Schϋtte

Aerospace Engineering

The numerical simulation of the flow for the VFE-2 configuration with rounded leading edges is presented. For the numerical simulation the Cobalt Code was used, which uses a cell-centered unstructured hybrid mesh approach. Several numerical results are presented for the steady RANS equations as well as for DES and DDES hybrid approaches. Within this paper the focus is related to the dual primary vortex flow topology, especially the sensitivity of the flow to angle of attack and Reynolds number effects. Reasonable results are obtained with both steady RANS and SA-DDES simulations. The results are compared and verified by experimental data, …

Multidisciplinary Design Optimization Of An Extreme Aspect Ration Hale Uav, Bryan Morrisey, Robert A. Mcdonald

Aerospace Engineering

Development of High Altitude Long Endurance (HALE) aircraft systems is part of a vision for a low cost communications/surveillance capability. Applications of a multi payload aircraft operating for extended periods at stratospheric altitudes span military and civil genres and support battlefield operations, communications, atmospheric or agricultural monitoring, surveillance, and other disciplines that may currently require satellite-based infrastructure. The central goal of this research was the development of a multidisciplinary tool for analysis, design, and optimization of HALE UAVs, facilitating the study of a novel configuration concept. Applying design ideas stemming from a unique WWII-era project, a "pinned wing" HALE aircraft …

Cost-Benefit Analysis Of Error Reduction For Complex Systems, Robert A. Mcdonald

Aerospace Engineering

The cost-benefit tradeoff of analysis fidelity in complex systems analysis has been posed as an optimization problem providing quantitative guidance for investment in improving analysis. A nonlinear constrained optimizer to solve this problem has been integrated into an error tradeoff environment providing an intuitive tool for the decision maker to consider investment in fidelity at the same time as design decisions are considered. An example demonstrates the efficacy of the improved interface to enable fidelity improvement investment decisions.

Orbital Propagators For Horizon Simulation Framework, Mitra Farahmand

Master's Theses

This thesis describes the models of four common orbital propagators and outlines the process of integrating them into the Horizon Simulation Framework (HSF). The results of the Two-Body, J2, and J4 propagators from the HSF are then compared against the outcomes of these propagators in MATLAB and Satellite Toolkit (STK). The MATLAB algorithms verify the functionality of the propagators and determine the accuracy of the HSF implementation. The compassion against STK validates the formulation of the HSF propagators. In order to equip the HSF with a more precise means of orbit determination, adding the Simplified General Perturbations 4 (SGP4) propagator …

Rayleigh Flow Of Two-Phase Nitrous Oxide As A Hybrid Rocket Nozzle Coolant, Lauren May Nelson

Master's Theses

The Mechanical Engineering Department at California Polytechnic State University in San Luis Obispo currently maintains a lab-scale hybrid rocket motor for which nitrous oxide is utilized as the oxidizer in the combustion system. Because of its availability, the same two-phase (gas and liquid) nitrous oxide that is used in the combustion system is also routed around the throat of the hybrid rocket’s converging-diverging nozzle as a coolant. While this coolant system has proven effective empirically in previous tests, the physics behind the flow of the two-phase mixture is largely unexplained. This thesis provides a method for predicting some of its …

The Interaction Between Throttling And Thrust Vectoring Of An Annular Aerospike Nozzle, David Michael Imbaratto

Master's Theses

Applied research and testing has been conducted at the Cal Poly San Luis Obispo High-pressure Blow-Down facility to study the affects of throttling in a thrust-vectored aerospike nozzle. This study supports the ongoing research at Cal Poly to effectively thrust vector a hybrid rocket motor. Such thrust vectoring is achieved by small secondary ports in the nozzle body that are perpendicular to the main nozzle. The testing conducted included characterizing and comparing the performance of a straight aerospike nozzle to that of a thrust-vectored aerospike nozzle. Throttling effects on the aerospike nozzle in an unvectored and in a vectored configuration …

Development Of A High Performance Micropropulsion System For Cubesats, Christopher Lorian Biddy

Master's Theses

Picosatellites are defined as satellites with a mass between 0.1 and 1kg (Miniaturized satellite). Picosatellites are typically designed to work together or function in formations (Miniaturized satellite). A specific type of Picosatellite known as CubeSats were introduced in 1999 and since then have increased in popularity so that there are now over 80 CubeSat programs around the world. CubeSats are defined as cubic units 10cm on each side and no more than 1kg in mass. CubeSats are required to conform to the CubeSat Standard created by California Polytechnic State University and Stanford University and be compatible with Cal Poly’s P-POD …

On-Board Orbit Determination And 3-Axis Attitude Determination For Picosatellite Applications, John Arthur Bowen

Master's Theses

This thesis outlines an orbit determination and 3-axis attitude determination system for use on orbit as applicable to 1U CubeSats and other picosatellites. The constraints imposed by the CubeSat form factor led to the need for a simple configuration and relaxed accuracy requirements. To design a system within the tight mass, volume, and power constraints inherent to CubeSats, a balance between hardware complexity, software complexity and accuracy is sought. The proposed solution consists of a simple orbit propagator, magnetometers with a magnetic field look-up table, Sun sensors with an analytic Sun direction model, and the TRIAD method to combine vector …

Application Of Volterra Functions To X-31 Aircraft Model Motion, United States Air Force Academy, Russell M. Cummings

Aerospace Engineering

Recent advances towards an efficient computational method for accurately determining the stability and control characteristics of an aircraft are discussed and critiqued. The present approach with greatest promise is to reduce the number of high-fidelity CFD simulations by using Volterra functions Reduced Order Modeling. This type of reduced order model is a predictive model which has a unique training maneuver -a unit impulse. The advantage of such an approach is the fast prediction of the aerodynamic characteristics of an aircraft. This article presents the results of application of the Volterra functions ROM for prediction of linear movement of a 2D …

Comparison Of Overset Grid And Grid Deformation Techniques Applied To 2-Dimensional Naca Airfoils, Charles M. Hoke, Robert K. Decker, Russell M. Cummings, David R. Mcdaniel, Scott A. Morton

Aerospace Engineering

This paper documents a comparison of overset grid and grid deformation schemes applied to flapped and non-flapped NACA airfoil configurations in order to determine the relative accuracy and computational efficiency of each method. This study is part of a larger effort to use computational fluid dynamics to perform moving control surface calculations. Three different cases, using both overset and deformed grids, are considered, including: a) lift and moment comparison of a quasi-steady, non-flapped 0012 airfoil, b) lift and moment comparison of a dynamically pitching non-flapped 0012 airfoil, and c) lift comparison of a dynamic pitching and oscillating flapped 0012 airfoil. …

Satellite Formation Flight Navigation Using The Clohessy-Wiltshire Equations, Anna Kimmich

Aerospace Engineering

This report presents the design and simulation of a satellite navigation program using Matlab. The program allows any number of independent satellites to navigate in a co-planar cluster formation in a circular orbit with no input besides its location coordinates from a simulated GPS unit and the relative location of other satellites from a simulated on-board sensor. This navigation program uses a potential field-like function to calculate the desired satellite position within the formation. It uses the Clohessy-Wiltshire equations to calculate the impulsive maneuvers needed to achieve and maintain the formation.