Effect of an aeroelastic film on confined subsonic cavity resonance

EFFECT OF AN AEROELASTIC FILM ON CONFINED SUBSONIC CAVITY RESONANCE by Melissa Carter B.S., Mechanical Engineering, University of New Mexico, 2001 M.S., Mechanical Engineering, University of New Mexico, 2011 ABSTRACT Two shallow three-dimensional cavities were used to study the effect on cavity resonance of an aeroelastic film placed on the wall opposite the cavity in confined (duct) flow. Flow speeds were very low subsonic with Mach number varying from 0.05 to 0.10. The cavities have length-to-depth ratios of 2.5 and 1.5, with identical depths. It was expected that the aeroelastic film in flutter would interact with acoustic signals from the cavity to enhance or inhibit cavity pressure oscillations. Two different film tensions were applied to the film to affect flutter conditions. However, the film support mechanism design did not allow flutter, and each film experienced static displacement caused by outside air pressure. Cavity sound data recorded by a microphone was compared for tests with and without the film. The effects of film tension were insignificant, primarily because the film was not in flutter. The longer cavity exhibited higher sound pressure levels over the entire range of frequencies with an aeroelastic film present. The shorter cavity showed smaller differences, perhaps because the film is longer than the cavity. The presence of an aeroelastic film did affect the shear-layer frequencies in the cavities. For Cavity 2, higher amplitude peaks in the range of estimated resonance frequencies were observed with the film present. The results for the longer cavity indicate that a film on the opposite wall will interact with cavity pressure oscillations to affect sound pressure levels in resonance

School

This project asked the question: What is the role of the undergraduate liberal arts institution in American society, now? I initially searched for answers through secondary research. This did not provide me with a single, concrete answer, but contextualized the topic and showed me that there is a multitude of roles that the university plays in society. I then formed and trained an ensemble and together we explored these roles through group discussion and exhaustive improvisation. Out of the many answers that presented themselves, we focused on the concept that the primary purpose of the university is to create the ideal democratic citizen. This proposition raised more questions such as: how does the university select who is fit to be developed? How do they go about developing these students? And what defines the ideal democratic citizen? Our presentation was an eight hour long site-specific performance art piece called School. It was composed primarily of long-form improvisational games. In the end, we not only learned an enormous amount about the university but also gained experience creating a durational performance and through all of this expanded our understanding of the relationship between the content and the structure of a theatrical piece

Exploring the relationship between changes in bone mineral density, lean body mass, and hormones in active, adult males with osteopenia after a 12-month exercise intervention

Title from PDF of title page (University of Missouri--Columbia, viewed on March 6, 2013).The entire thesis text is included in the research.pdf file; the official abstract appears in the short.pdf file; a non-technical public abstract appears in the public.pdf file.Thesis advisor: Dr. Pamela HintonIncludes bibliographical references.M.S. University of Missouri--Columbia 2012."December 2012"INTRODUCTION: Weight-bearing exercise may positively affect bone via muscle contractions, impact forces, and hormonal changes; however, the importance of these factors remains controversial. PURPOSE: To determine if 12-months of resistance training (RT) or plyometric (PLY) exercise beneficially impacts bone mineral density (BMD) in active, osteopenic men, and to examine the potential osteogenic mechanisms. METHODS: Participants were randomized to 12-months of RT or PLY. LBM and BMD of the whole body, weight-bearing, and non-weight-bearing sites were measured at 0- and 12-months. Testosterone, free testosterone, and estradiol concentrations were assessed using ELISA kits. RESULTS: Whole body and leg BMD increased with no differences between RT and PLY. Hip BMD increased in the RT group. The relationship between the percent change in whole body LBM and the percent change in leg BMD was positive in the PLY group and negative in the RT group. The percent change in whole body LBM was positively correlated with the percent change in hip BMD in the PLY group. The percent change in arm LBM was positively correlated with the percent change in arm BMD in the RT group. The percent change in testosterone and estradiol were negatively correlated with the percent change in hip BMD. DISCUSSION: In conclusion, muscle contraction forces and impact forces may be potential mechanisms for osteogenesis in osteopenic men

Bending the Arc Toward Justice: The Current Era of Juvenile Justice Reform in Georgia

America’s juvenile justice system is experiencing another era of reform. The formal juvenile justice system originated from the ideology and methods of social reformers who viewed deviant behavior as a treatable condition and sought redemption of criminal youth. In the first era of reform, that view powered the state’s exercise of its parens patriae authority and produced a paternalistic judiciary and institutions that used custody as a means of achieving social control. Over time, changing political and social views of childhood and a growing recognition in the law of children as rights-holders shifted the system’s focus away from the rehabilitative ideal. At its extreme, this second era of reform abandoned the developmental view of youth crime in favor of a public safety orientation and resulted in a system overcorrection. The present era of juvenile justice system reform preserves the developmental approach and restores the rehabilitative ideal while striking a better balance between state interests and the rights of individual children. This Article traces the history of the juvenile justice system and reflects on the present era of system reform. Early indications suggest that, through the use of evidence previously not available, the current era of juvenile justice system reform has the potential to restore the rehabilitative ideal on which the system was founded without compromising public safety goals or the legal rights of system-involved children. This Article specifically documents the effort, engagement, and leadership across public and private sectors to effectuate such balanced state-level reform in Georgia—the focus of this Symposium

FUN3D and USM3D Analysis of the Propulsion Aerodynamic Workshop 2018 S-Duct Test Case

This work presents the results of Fun3D and USM3D analyses that were performed for the 4th AIAA Propulsion Aerodynamics Workshop (PAW). The PAW workshop is separated into three sections that focus on internal duct flows, nozzle flows and a special topic. This paper focuses on the internal duct flow section of PAW04 while an accompanying paper discusses the analyses performed for the nozzle portion. For the internal duct flow section, the PAW04 participants were provided with the two configurations consisting of an S-duct with and without aerodynamic interface plane (AIP) rake legs modeled. The participants were asked to perform a grid refinement study as well as a turbulence model study for the configuration with the rake legs. The analyses discussed here were performed on custom grids developed under the guidelines of the workshop. Additionally, the paper discusses the development and use of flow controllers for matching the desired flow characteristics. The results show that both solvers do well for predicting internal flow characteristics of the S-duct based on direct comparison with the experimental data. However, the CFD-to-CFD comparison proved to be more challenging due to the localized occurrence of supersonic flow near the rake legs when using the mass flow controller. A turbulence model study was performed to compare the two-equation SST model to the SA-QCR model. The results show that although the turbulence model does affect the solution, it makes a minimal impact on pressure recovery and inlet distortion intensity for this case. Suggestions for future workshops include gridding guidelines similar to those employed for the Drag Prediction Workshop series for the grid refinement study and a time accuracy study

A Grid Sourcing and Adaptation Study Using Unstructured Grids for Supersonic Boom Prediction

NASA created the Supersonics Project as part of the NASA Fundamental Aeronautics Program to advance technology that will make a supersonic flight over land viable. Computational flow solvers have lacked the ability to accurately predict sonic boom from the near to far field. The focus of this investigation was to establish gridding and adaptation techniques to predict near-to-mid-field (<10 body lengths below the aircraft) boom signatures at supersonic speeds using the USM3D unstructured grid flow solver. The study began by examining sources along the body the aircraft, far field sourcing and far field boundaries. The study then examined several techniques for grid adaptation. During the course of the study, volume sourcing was introduced as a new way to source grids using the grid generation code VGRID. Two different methods of using the volume sources were examined. The first method, based on manual insertion of the numerous volume sources, made great improvements in the prediction capability of USM3D for boom signatures. The second method (SSGRID), which uses an a priori adaptation approach to stretch and shear the original unstructured grid to align the grid and pressure waves, showed similar results with a more automated approach. Due to SSGRID s results and ease of use, the rest of the study focused on developing a best practice using SSGRID. The best practice created by this study for boom predictions using the CFD code USM3D involved: 1) creating a small cylindrical outer boundary either 1 or 2 body lengths in diameter (depending on how far below the aircraft the boom prediction is required), 2) using a single volume source under the aircraft, and 3) using SSGRID to stretch and shear the grid to the desired length

A Quiet Revolution: How Judicial Discipline Essentially Eliminated Foster Care and Nearly Went Unnoticed.

This Article argues that juvenile court judges can safely reduce the number of children entering foster care by faithfully and rigorously applying the law. Judges often fail to perform this core functon when a state child welfare agency separates a child from their family. Judges must perform their role as impartial gatekeeper despite the temptation to be omnipotent moral busybodies

Remittance of participant's retirement contributions to the State Optional Retirement Program

This paper discusses the problem: How can the South Carolina Retirement Systems mandate or encourage employers to remit the retirement contributions of participants in the State Optional Retirement Program to their chosen vendor within a defined time frame

Blended-Wing-Body Transonic Aerodynamics: Summary of Ground Tests and Sample Results

The Blended-Wing-Body (BWB) concept has shown substantial performance benefits over conventional aircraft configuration with part of the benefit being derived from the absence of a conventional empennage arrangement. The configuration instead relies upon a bank of trailing edge devices to provide control authority and augment stability. To determine the aerodynamic characteristics of the aircraft, several wind tunnel tests were conducted with a 2% model of Boeing's BWB-450-1L configuration. The tests were conducted in the NASA Langley Research Center's National Transonic Facility and the Arnold Engineering Development Center s 16-Foot Transonic Tunnel. Characteristics of the configuration and the effectiveness of the elevons, drag rudders and winglet rudders were measured at various angles of attack, yaw angles, and Mach numbers (subsonic to transonic speeds). The data from these tests will be used to develop a high fidelity simulation model for flight dynamics analysis and also serve as a reference for CFD comparisons. This paper provides an overview of the wind tunnel tests and examines the effects of Reynolds number, Mach number, pitch-pause versus continuous sweep data acquisition and compares the data from the two wind tunnels