Aerospace Engineering Commons^™

Nonlinear Uav Flight Control Using Command Filtered Backstepping, Brian M. Borra

Master's Theses

The aim of this effort is to implement a nonlinear flight control architecture, specifically flight path control via command filtered backstepping, for use in AME UAS's Fury® 1500 unmanned flying wing aircraft. Backstepping is a recursive, control-effort minimizing, constructive design procedure that interlaces the choice of a Lyapunov function with the design of feedback control. It allows the use of certain plant states to act as intermediate, virtual controls, for others breaking complex high order systems into a sequence of simpler lower-order design tasks.

Work herein is a simplified implementation based on publications by Farrell, Sharma, and Polycarpou. Online approximation …

Experimental Investigation Of A 2-D Air Augmented Rocket: High Pressure Ratio And Transient Flow-Fields, Josef S. Sanchez

Master's Theses

A 2-D Air Augmented Rocket, the Cal Poly Air Augmented Rocket (CPAAR) Test Apparatus operating as a mixer-ejector was tested to investigate high stagnation pressure ratio and transient flow fields of an ejector. The primary rocket ejector was supplied with high pressure nitrogen at a maximum chamber pressure of 1758 psia and a maximum mass flow rate of 1.4 lb/s. The secondary flow air was entrained from a fixed volume plenum chamber producing pressures as low as 3.3 psia. The maximum total pressure ratio achieved was 221. The original CPAAR apparatus was rebuilt re-instrumented and capability expanded. A fixed volume …

The Importance And Challenge Of Launch Environment Testing, Christina Diaz

Aerospace Engineering

This report discusses the purpose and effect of environmental testing, particularly vibration, shock and acoustic tests, in the aerospace industry. Vibration, shock, and acoustic testing are methods that are used to quantify and analyze the physical phenomenon of the launch environment on a payload or launch vehicle. The importance of innovation in testing and understanding of failures is crucial to a successful spacecraft mission. The advancement and precision of these testing methods is also explored in this report such as the invention of the 6 Degree of Freedom (DoF) vibration table and solutions to data acquisition issues recently discovered in …

Effect Of End-Plate Tabs On Drag Reduction Of A 3d Bluff Body With A Blunt Base, Jarred Michael Pinn

Master's Theses

This thesis involves the experimental testing of a bluff body with a blunt base to evaluate the effectiveness of end-plate tabs in reducing drag. The bluff body is fitted with interchangeable end plates; one plate is flush with the rest of the exterior and the other plate has small tabs protruding perpendicularly into the flow. The body is tested in the Cal Poly 3ft x 4ft low speed wind tunnel. Testing is conducted in three phases.

The first phase was the hot-wire measurement of streamwise velocity of the near wake behind the bluff body. An IFA300 thermal anemometry system with …

Debris Propagation Due To A Space Vehicle Breakup At High Altitudes, Juan A. Alvarado

Doctoral Dissertations and Master's Theses

Recently, there has been a surge of interest in the estimation of the extent of the airspace containing falling debris due to a space vehicle breakup. A precise computation of propagation of debris to the ground is not practical for many reasons. There is insufficient knowledge of the initial state vector, ambient wind conditions and the key parameters including the ballistic coecients. In addition, propagation of all debris pieces to the ground would require extensive computer time. In this thesis, a covariance propagation method is introduced for the estimation of debris propagation due to a space vehicle breakup. The falling …

Study Of Mechanical And Thermal Behavior Of Polymeric Ablator Using Md, Abhishek Kumar, Veera Sundararaghavan

Ablation Workshop

The thermal protection materials used for spacecraft heat shields are subjected to various thermal and mechanical loads during an atmospheric entry which can threaten the structural integrity of the system. This paper describes the development of a molecular dynamics approach to understand the mechanical and thermal behavior of high temperature polymers. One such material PICA has successfully flown on the Stardust spacecraft and is the TPS material chosen for the Mars Science Laboratory (MSL) and SpaceX Dragon spacecraft. Although such polymers have good structural properties at moderate temperature,they became structurally weak at extreme region of temperature and loads. In order …

Aerothermal Characterization Of Silicon Carbide-Based Tps In High Enthalpy Airflow, Francesco Panerai, Olivier Chazot

Ablation Workshop

Inductively-coupled plasma generators provide an ideal environment to reproduce the aerothermal heating experienced by a spacecraft re-entering a planetary atmosphere. The flight boundary layer chemistry is duplicated around a TPS model, ensuring a similarity between the flight and ground stagnation-point heat flux.

Experiments conducted in an induction plasmatron on silicon carbide-based thermal protection materials will be described. Several specimens are tested under a wide range of pressure and temperature conditions and investigated by means of infrared radiometry and optical emission spectroscopy. The plasma to which the materials are exposed is characterized in details by calorimetric and Pitot pressure measurements, and …

Methodology For Ablation Investigations In The Vki Plasmatron Facility: Preliminary Results With A Carbon Fiber Preform, Bernd Helber, Olivier Chazot, Annick Hubin, Thierry Magin

Ablation Workshop

Following the current developments of a new class of low-density, carbon/resin composite ablators, new efforts were initiated at the VKI on ablation research to understand the complex material response under reentry conditions and to develop and validate new material response models. Promising experimental results were obtained by testing the low-density monolytic composite ablator (MonA) in the 1.2MW inductively heated VKI Plasmatron facility. The application of a high speed camera with short exposure times (2μs) enabled in-situ analysis of both (3D) surface recession and spallation and further made it possible to demonstrate the outgassing effects of pyrolizing ablators. A change in …

Thermo-Chemical And Mechanical Coupled Analysis Of Swelling, Charring And Ablative Materials For Re-Entry Applications, Gregory Pinaud

Ablation Workshop

One of the major challenges in the design of atmospheric reentry vehicles is the optimization of the thermal protection system (TPS). During a reentry, the vehicle encounter severs heating and mechanical stress. A robust sizing is therefore essential to insure vehicle integrity and the mission success. In order to maximize the payload mass of the vehicle, lightweight charring ablators are commonly chosen as TPS materials for this one shot mission.

To predict the behaviour of the TPS ablative materials under pyrolysis for reentry applications, Astrium ST initiated the development of a specific module of the finite element software SAMCEF: AMARYLLIS. …

Coupled Computation Of Fluid And Material Response For Non-Charring Ablative Materials In Hypersonic Flow, Jonathan E. Wiebenga, Iain D. Boyd

Ablation Workshop

Hypersonic vehicles are subjected to high heat loads throughout their flight trajectories, and as a result, some form of thermal protection system (TPS) is required to ensure the vehicle’s survival. Accurate prediction of the behavior of these materials in a hypersonic environment is crucial to the efficient design of a hypersonic flight vehicle. It can be very costly and difficult, however, to experimentally replicate the flow conditions found in many hypersonic regimes, and for this reason it is desirable to be able to simulate the behavior of TPS materials under these flight conditions. This study aims to improve the modeling …

Uncertainty Analysis Of Reaction Rates In A Finite Rate Gas-Surface Model, Thomas E. Schwartzentruber

Ablation Workshop

A finite–rate–catalytic wall boundary condition incorporated into hypersonic flow simulations is investigated. Benchmark simulations of hypersonic flow over a cylinder are presented using the finite–rate–catalytic model parameterized with a test air–silica chemical model comprising the gas–surface reaction mechanisms and their associated rates. It is demonstrated that backwards recombination rates should not be arbitrarily set but must be consistent with the gas–phase thermodynamics, otherwise a drift from the equilibrium state may occur. The heat flux predicted by the finite rate model lies between non–catalytic and super–catalytic limits depending on the surface temperature. It is found that even for a constant surface …

Cfd Ablation Predictions With Coupled Gsi Modeling For Charring And Non-Charring Materials, Daniele Bianchi, Alessandro Turchi, F. Nasuti, M. Onofri

Ablation Workshop

To this day, a major objective of TPS design is to reduce empiricism, and to increase fundamental modeling capability through increased understanding. One of the most challenging aspect is the proper coupling between the material response and the external flow field. With this regard, the goal of this research activity is the improvement of the numerical modeling capabilities through the development of advanced CFD tools integrated with Gas-Surface Interaction (GSI) modeling.

Numerical prediction of ablation is ambitious and cpu-time demanding due to the complex multiphase physical and chemical processes that occur. With improvements in computational algorithms and advances in computer …

Radiative Transfer Equation Solver Module For Coupled Simulation Of Hypersonic Flows, Ranjan S. Mehta, Paul J. Dionne, Samuel F. Owens

Ablation Workshop

Accurate numerical modeling of the aerothermal environment around an ablation-cooled hypersonic re-entry vehicle requires high-fidelity models for processes such as non-equilibrium surface themochemistry, non-equilibrium pyrolysis chemistry, multi-scale radiation, spallation and charring. It is expected that, these models when utilized in a coupled manner will be able to accurately capture the possible nonlinear interactions between various phenomena in a computationally efficient manner. Development of a coupled radiative solver is currently being carried out as part of a joint effort between CFDRC, University of Michigan and University of Kentucky to develop a fully coupled method of simulating atmospheric entry flows and response …

Modeling Of Heat Transfer Attenuation By Ablative Gases During The Stardust Re-Entry, Alexandre Martin, Iain D. Boyd

Ablation Workshop

The great majority of modern space vehicles designed for planetary exploration use ablative materials to protect the payload against the high heating environment experienced during re-entry. In order to properly model and predict the aerothermal environment of the vehicle, it is imperative to account for the gases produced by ablation processes. In the case of charring ablators, where an inner resin is pyrolyzed at a relatively low temperature, the composition of the gas expelled into the boundary layer is complex and may lead to thermal chemical reactions that cannot be captured with simple flow chemistry models. In order to obtain …

Ablation Modeling Of A Solid Rocket Nozzle, Mark E. Ewing, Galen H. Richards, Micheal P. Iverson, Daron A. Isaac

Ablation Workshop

No abstract provided.

Definition Of Ablation Test-Case Series #3, Tom Van Eekelen, Jean R. Lachaud, Alexandre Martin, Ioana Cozmuta

Ablation Workshop

The test-case series #3 will be a further extension of the tests defined within the framework of the NASA ablation modelling workshops. In order to reduce the amount of work, all tests within test-case series #3, will use the TACOT material defined by Lachaud et al. The main goal of this new series, is to test the 3D modelling capabilities of the participating codes. The first 1D results were presented at the 4th Ablation workshop, and together with the results of the second test-case series, will be discussed and analyzed more thoroughly at the 5th Ablation Workshop, Feb. 28- March …

Ablation Test Case Series #2. Mopar: Results For The Inter-Code Calibration, Jonathan E. Wiebenga, Iain D. Boyd, Alexandre Martin

Ablation Workshop

No abstract provided.

Ablation Test Case Series #2. Itrac Results, Mark E. Ewing

Ablation Workshop

No abstract provided.

Ablation Test Case Series #2. Amaryllis Results, Tom Van Eekelen, Jean-Marc Bouilly

Ablation Workshop

No abstract provided.

Ablation Test Case Series #2. Be13 Results, Jean-Marc Bouilly

Ablation Workshop

No abstract provided.