Aerodynamics and Fluid Mechanics Commons^™

Comparative Study On Performance Accuracy Of Three Probe And Five Probe Flow Analysers For Wind Tunnel Testing, Akhila Rupesh Ms, J V Muruga Lal Jeyan Dr

International Journal of Aviation, Aeronautics, and Aerospace

In the field of inviscid fluid flow studies, the theoretical concept has to be developed even more. In order to make it possible, it is very important to supplement the concepts with strong experimental results. While performing experimentation, various accepts of design can be determined with factors influencing the and also required modification can be recommended in a more systematic and economic manner. Also, the aim objective of the experiment is to extend the underlying theory and to produce new designs with improvements that can be great support to the advancement in technology. In experimental analysis, wind tunnels are used …

Aerodynamic Characterization Of Bio-Mimicked Pleated Dragonfly Aerofoil, Md Akhtar Khan, Chinmaya Padhy

International Journal of Aviation, Aeronautics, and Aerospace

The work inspired by the dragonfly wing corrugation positioned at the front wing's radius section lying at 40% of the total wingspan of forewing from the root section. During gliding flight, dragonfly wings presumed to be an ultra-light aerofoil due to its well-defined cross-sectional corrugation. The aerodynamic simulation carried out to understand the aerodynamic performance of a bio-mimetic dragonfly corrugated airfoil at low Reynolds number range of 75000-150000 to explore the potential advantages of pleated airfoils at a varying angle of attack from 0° to 12°. CFD analysis accomplished by using ANSYS Fluent to understand the aerodynamic performance of the …

Nebulizer-Based Systems To Improve Pharmaceutical Aerosol Delivery To The Lungs, Benjamin M. Spence

Theses and Dissertations

Combining vibrating mesh nebulizers with additional new technologies leads to substantial improvements in pharmaceutical aerosol delivery to the lungs across therapeutic administration methods. In this dissertation, streamlined components, aerosol administration synchronization, and/or Excipient Enhanced Growth (EEG) technologies were utilized to develop and test several novel devices and aerosol delivery systems. The first focus of this work was to improve the poor delivery efficiency, e.g., 3.6% of nominal dose (Dugernier et al. 2017), of aerosolized medication administration to adult human subjects concurrent with high flow nasal cannula (HFNC) therapy, a form of continuous-flow non-invasive ventilation (NIV). The developed Low-Volume Mixer-Heater (LVMH) …

Theoretical Study Of Magnetic Particles In A Shear Flow Subjected To A Uniform Magnetic Field, Christopher A. Sobecki

Doctoral Dissertations

"Magnetic manipulation of non-spherical magnetic microparticles is important for applications in shape-based and magnetic-based separations such as waste management, disease diagnostics, drug delivery, and mining. Manipulations of magnetic microparticles also include chain formation to assemble compositions for electronics, drug loading designs, and magnetorheological fluids for smart armor, hydraulic brakes, and dampers. In microfluidic devices, separation-formation-effectiveness depends on the shape of the channel, the shear rate, and the magnetic field strength and direction.

Particle separation and chain formation involved highly complex and computational expense-demanding studies in microfluidic devices, magnetic fields, and particle- particle/wall interactions. This research took complex experimental studies and …

Novel Adaptive Sampling Algorithm For Pod-Based Non-Intrusive Reduced Order Model, Jiachen Wang, Xiaosong Du, Joaquim R.R.A. Martins

Mechanical and Aerospace Engineering Faculty Research & Creative Works

The proper orthogonal decomposition (POD) based reduced-order model (ROM) has been an effective tool for flow field prediction in the engineering industry. The sample selection in the design space for POD basis construction affects the ROM performance sensitively. Adaptive sampling can significantly reduce the number of samples to achieve the required model accuracy. In this work, we propose a novel adaptive sampling algorithm, called conjunction sampling strategy, which is based on proven strategies. The conjunction sampling strategy is demonstrated on airfoil flow field prediction within the transonic regime. We demonstrate the performance of the proposed strategy by running 10 trials …

A Convolutional Neural Network Model Based On Multiscale Structural Similarity For The Prediction Of Flow Fields, Yifu An, Xiaosong Du, Joaquim R.R.A. Martins

Mechanical and Aerospace Engineering Faculty Research & Creative Works

We have seen the emerging applications of deep neural networks for flow field predictions in the past few years. Most of the efforts rely on the increased complexity of the model itself or take advantage of novel network architectures, such as convolutional neural networks (CNN). However, reaching low prediction error cannot guarantee the quality of the predicted flow fields in terms of the perceived visual quality. This work introduces the multi-scale structural similarity (MS-SSIM) index method for flow field prediction. First, we train CNN models using the commonly used root mean squared error (RMSE) loss function as the reference. Then …

Dynamic Behavior And Interactions Of Ferrofluid Droplets Under Magnetic Fields In Low Reynolds Number Flows, Md Rifat Hassan

Doctoral Dissertations

Digital microfluidics in combination with emulsion microfluidics are crucial building blocks of droplet-based microfluidics, which are prevalent in a wide variety of industrial and biomedical applications, including polymer processing, food production, drug delivery, inkjet printing, and cell-based assays. Therefore, understanding the dynamics and interactions of droplets as well as the interactions between the droplets and solid surfaces are of great importance in order to improve the performance or product in these applications.

Recently, several studies in the literature have demonstrated the potential of magnetic fields in controlling the behavior of droplets in microscale; however, the fundamental mechanism behind the interesting …

Numerical Investigations Of Transient Wind Shear From Passing Vehicles Near A Road Structure (Part I: Unsteady Reynolds-Averaged Navier-Stokes Simulations), Hamid Rahai, Assma Begum

Mineta Transportation Institute

In this research, the authors performed unsteady numerical simulations of a moving Ahmed body under a freeway overpass at different distances from the bridge columns in order to evaluate transient wind shear and the wind load on these columns. Results have shown that when the vehicle is at 0.75W distance from the bridge columns, an unsteady wind speed of up to 24 m/s is observed at the columns with a pressure coefficient difference of 0.9. Here W is the width of the vehicle. These results indicate with an appropriate system for harnessing these wind energy potentials, significant renewable electric power …

Next-Generation Re-Entry Aerothermodynamic Modeling Of Space Debris Using Machine Learning, Nicholas Sia

Graduate Theses, Dissertations, and Problem Reports (ETD)

The number of resident space objects re-entering the atmosphere is expected to rise with increased space activity over recent years and future projections. Predicting the survival and impact location of the medium to large sized re-entering objects becomes important as they can cause on ground casualties and damage to property. Uncertainties associated with the re-entry process makes necessary a probabilistic approach, which can be computationally expensive when using high-fidelity numerical methods for estimating aerothermodynamic properties. To date, object-oriented analysis is the dominant tool used for atmospheric re-entry modeling and simulation, where aerothermodynamic coefficients are used to determine the risk a …

Design, Fabrication And Analysis Of Novel Dragonfly-Bioinspired, Flapping Wing System For A Micro Air Vehicle, Erfan Salami

Student Works (2020-2029)

In the recent decades, the design and development of biomimetic micro air vehicles (BMAV) have gained increased interest from the global scientific and engineering communities. This has given greater motivation to study and understand the aerodynamics involved with winged insects. Dragonflies demonstrate unique and superior flight performance than most of the other insect species and birds. They are capable of sustained gliding flight as well as hovering and are able to change direction very rapidly. Pairs of independently controlled forewings and hindwings give them an agile flying ability. There are still many technological challenges involved with designing the BMAV. One …

Dances And Escape Of The Vortex Quartet, Brandon Behring

Dissertations

This dissertation considers the linear stability of a one-parameter family of periodic solutions of the four-vortex problem known as 'leapfrogging' orbits. These solutions, which consist of two pairs of identical yet oppositely-signed vortices, were known to W. Gröbli (1877) and A. E. H. Love (1883) and can be parameterized by a dimensionless parameter related to the geometry of the initial configuration. Simulations by Acheson and numerical Floquet analysis by Tophøj and Aref both indicate, to many digits, that the bifurcation occurs at a value related to the inverse square of the golen ratio. Acheson observed that, after an initial period …

Design And Control Techniques Of The Open-Circuit Subsonic Wind Tunnel With Closed Testing Section, Jamshid Yakhshilikov, Jamshid Inoyatkhodjaev

Acta of Turin Polytechnic University in Tashkent

This paper will describe the design and control techniques of the open-circuit subsonic wind tunnel with closed testing section (WT) for study purpose. The goal is to design a WT that can be tested at a wind speed of 30 m/s, where the desired cross-sectional area of the test chamber is 0.5x0.5 m. The pressure drop inside the WT has been calculated in order to select one of the available axial fans from the manufacturer’s catalog, and computational fluid dynamics (CFD) was performed to check the result. In order to obtain a smooth airflow in the test section, a proportional …

Entrainment Processes For A Jet In Cross-Flow: The Quantification Of Turbulent Contributions And Their Importance On Accurate Modeling, Graham Asher Freedland

Dissertations and Theses

A jet in cross flow (JICF) is examined experimentally by injecting a stream of air into crossing fluid with an aim into quantifying entrainment process and downstream evolution. The behavior of JICF is important to fields ranging from turbine-blade cooling to smokestack pollution and volcanic eruption dynamics. Existing simplified volcanic plume models are tested; most importantly, the near-field contributions of complex interconnected vortex systems, which present significant uncertainties because they assume negligible turbulence. While jets in irrotational cross-flow have been investigated, this analysis has focused on the interaction between a turbulent jet in low and highly turbulent cross-flow created by …

The Varied Thermal Response Of Magnetic Iron-Oxide Nanoparticles During Induction Heating In Liquid And Solid-Liquid Phase Change Mediums, Joshua Tompkins

Graduate Theses and Dissertations

This study investigates the induction heating response of uncapped iron oxide nanoparticles sonically dispersed as a nanofluid and mechanically distributed in solid phase change materials. The nanoparticles examined have a mean diameter of 14.42 nm and are magnetically heated in an alternating magnetic field at an amplitude of 72.6 kA/m at frequencies of 217, 303, and 397 kHz. Nanoparticle characterization was undertaken through transition electron microscopy, x-ray diffraction, and dynamic light scattering when in suspension. Carrier fluids were characterized through viscosity, heat capacity, and density measurements which were used in the calorimetric calculation of the specific absorption rate (SAR) of …

Numerical Analysis Of A Circulation Control Wing, Luke W. Bodkin

Master's Theses

The objective of this thesis was to develop an experimental method to research circulation control wings using numerical analysis. Specifically, it is of interest to perform 3D wind tunnel testing on a circulation control wing in the Cal Poly Low Speed Wind Tunnel (CPLSWT). A circulation control wing was designed and analyzed to determine the feasibility of this testing.

This study relied on computational fluid dynamics (CFD) simulations as a method to predict the flow conditions that would be seen in a wind tunnel test. A CFD simulation was created of a wing model in a wind tunnel domain. Due …

Field Testing The Effects Of Low Reynolds Number On The Power Performance Of The Cal Poly Wind Power Research Center Small Wind Turbine, John B. Cunningham

Master's Theses

This thesis report investigates the effects of low Reynolds number on the power performance of a 3.74 m diameter horizontal axis wind turbine. The small wind turbine was field tested at the Cal Poly Wind Power Research Center to acquire its coefficient of performance, C­_p, vs. tip speed ratio, λ, characteristics. A description of both the wind turbine and test setup are provided. Data filtration and processing techniques were developed to ensure a valid method to analyze and characterize wind power measurements taken in a highly variable environment. The test results demonstrated a significant drop in the …

Numerical Analysis Of Multi-Functional Surface Acoustic Wave Sensor, Xin Xu

Doctoral Dissertations and Master's Theses

A surface acoustic wave (SAW) sensor can have broad industrial applications due to its compact size, low cost-effectiveness, and versatility of sensible measurands, as well as the wireless capabilities. In this study, a theoretical modeling approach accompanied by a MATLAB-based algorithm of the SAW device is first presented. With the designed dimensional parameters and selected material properties, numerical analyses are performed using COMSOL Multiphysics to validate the theoretical results. Various postprocessing responses of the propagated SAWs in both time and frequency domains, such as time delay, insertion loss, and frequency shift, are examined to evaluate the device performances. Also, the …

Hypersonic Heat Transfer Load Analysis In Star-Ccm+, Robert Comstock

Master's Theses

This thesis investigates the capabilities of STAR-CCM+, a Computational Fluid Dynamics (CFD) software owned by Siemens, in predicting hypersonic heat transfer loads on forward-facing surfaces. Results show that STAR-CCM+ predicted peak heat transfer loads within +/- 20% of experimental data on the leading edge of a delta wing design from the X-20 Dyna-Soar program with 73^o of sweep. Steady-state laminar simulations were run as replications of wind tunnel tests documented in NASA CR-535, a NASA technical report that measured and studied the hypersonic pressure and heat transfer loads on preliminary X- 20 wing designs across a wide range of …

Celebrating 90-Orbits Around The Sun, Stafford Air & Space Museum

Programs

In celebration of the 90th birthday of Oklahoma astronaut and aerospace legend, Gen. Thomas P. Stafford, the Stafford Air & Space Museum in Weatherford, Oklahoma is offering free admission on September 17th, 2020.

Unless stated otherwise within this repository collection, all materials are shared under the following Creative Commons license: [Creative Commons Attribution-NonCommercial 4.0 International License].

Resonant Triad Interactions In One And Two-Layer Systems, Malik Chabane

Dissertations

This dissertation is a study of the weakly nonlinear resonant interactions of a triad of gravity-capillary waves in systems of one and two fluid layers of arbitrary depth, in one and two-dimentions. For one-layer systems, resonant triad interactions of gravity-capillary waves are considered and a region where resonant triads can be always found is identified, in the two-dimensional wavevector angles-space. Then a description of the variations of resonant wavenumbers and wave frequencies over the resonance region is given. The amplitude equations correct to second order in wave slope are used to investigate special resonant triads that, providing their initial amplitude …