Aerodynamics and Fluid Mechanics Commons^™

Numerical Simulation Of A Cryogenic Spray, Neel Kishorkumar Shah

Doctoral Dissertations and Master's Theses

Cryogenic sprays have many applications in modern engineering. Cooling of electronic equipment subject to high heat flows, surgical ablation of gastrointestinal mucosae or orbital maneuvering are a few examples of their versatility. However, the atomization of a cryogenic liquid is a complex process. During such an event, aerodynamic effects associated with secondary atomization are further affected by thermodynamic flashing. A better understanding of the characteristics of cryogenic sprays is then necessary to allow for improved design and optimization in applications. The overarching objective of this study is to document such characteristics. The numerical simulation was performed over cryogenic nitrogen spray …

Reduced-Order Dynamic Modeling And Robust Nonlinear Control Of Fluid Flow Velocity Fields, Anu Kossery Jayaprakash, William Mackunis, Vladimir Golubev, Oksana Stalnov

Publications

A robust nonlinear control method is developed for fluid flow velocity tracking, which formally addresses the inherent challenges in practical implementation of closed-loop active flow control systems. A key challenge being addressed here is flow control design to compensate for model parameter variations that can arise from actuator perturbations. The control design is based on a detailed reduced-order model of the actuated flow dynamics, which is rigorously derived to incorporate the inherent time-varying uncertainty in the both the model parameters and the actuator dynamics. To the best of the authors’ knowledge, this is the first robust nonlinear closed-loop active flow …

Assessment Of Conventional And Air-Jet Wheel Deflectors For Drag Reduction Of The Drivaer Model, Sandra K. S. Boetcher, Kaloki L. Nabutola

Publications

Aerodynamic drag is a large resistance force to vehicle motion, particularly at highway speeds. Conventional wheel deflectors were designed to reduce the wheel drag and, consequently, the overall vehicle drag; however, they may actually be detrimental to vehicle aerodynamics in modern designs. In the present study, computational fluid dynamics simulations were conducted on the notchback DrivAer model—a simplified, yet realistic, open-source vehicle model that incorporates features of a modern passenger vehicle. Conventional and air-jet wheel deflectors upstream of the front wheels were introduced to assess the effect of underbody-flow deflection on the vehicle drag. Conventional wheel-deflector designs with varying heights …

Background Flow Influence On Impulsive Jet-Driven Micro Droplet Dispersal, Vaishak Thiruvenkitam

Doctoral Dissertations and Master's Theses

Accurately predicting the airborne spread of infectious diseases is crucial in controlling the COVID­19 pandemic today. Studies have shown the spread of expiratory droplets depends on ambient thermodynamic conditions and flow properties of the jet emitted by the activity. However, the droplet spread in conditions of background flow is not yet comprehensively understood. This study uses the Eulerian­-Lagrangian model with k−ω turbulence modelling to simulate spread of particles and study the factors affecting it in a closed environment with a background flow. Respiratory activities are modeled as a non-­isothermal jet of air with droplets suspended in them in a predetermined …

Active Control Of Coherent Structures In An Axisymmetric Jet, Michael Marques Goncalves

Doctoral Dissertations and Master's Theses

The primary objective of this work is to develop high-fidelity simulation model for jet noise control predictions and quantify the sound reduction when an external source frequency mode excitation is imposed on the jet flow. Whereas passive approaches using mixing devices, such as chevrons, have been shown to reduce low-frequency noise in jet engines, such approaches incur a performance penalty since they result in a reduced thrust. To avoid a performance penalty in reducing jet noise, the current work investigates a open-loop active noise control (ANC) system that utilizes a unsteady microjet actuator on the nozzle lip in the downstream …

Extracting Microplastic From Anhydrous Beach Sediment Utilizing Relative Terminal Velocities, Grace Robertson, Jackson Schuler

Student Works

The primary intent of this research was to investigate and develop a method to extract microplastics from anhydrous beach sediment. Microplastic is found abundantly in coastal sea environments, including aqueous bottom sediment, and beach sediment (Sagawa, Kawaai, & Hinata, 2018). The scope of the microplastic extraction method in this case is limited to strictly the anhydrous beach sediment. The Venturi Effect and Burnoulli’s Principle have been utilized in the design of a nozzle with airflow that has been injected with a sediment and microplastic heterogenous mixture. A nozzle was designed to operate at the specific terminal velocity of sediment such …

Design And Flight-Path Simulation Of A Dynamic-Soaring Uav, Gladston Joseph

Doctoral Dissertations and Master's Theses

We address the development of a dynamic-soaring capable unmanned aerial vehicle (UAV) optimized for long-duration flight with no on-board power consumption. The UAV’s aerodynamic properties are captured with the integration of variable fidelity aerodynamic analyses. In addition to this, a 6 degree-of-freedom flight simulation environment is designed to include the effects of atmospheric wind conditions. A simple flight control system aids in the development of the dynamic soaring maneuver. A modular design paradigm is adopted for the aircraft dynamics model, which makes it conducive to use the same environment to simulate other aircraft models. Multiple wind-shear models are synthesized to …

Computational Investigation Of Perforated Plate Film Cooling Utilizing Conjugate Heat Transfer, Jonathan Sippel

Doctoral Dissertations and Master's Theses

The accuracy of modern state-of-practice computational fluid dynamics approaches in predicting the cooling effectiveness of a perforated plate film-cooling arrangement is evaluated in ANSYS Fluent. A numerical investigation is performed using the Reynolds Averaged Navier Stokes equations and compared to NASA Glenn’s available Turbulent Heat Flux 4 experimental measurements collected as a part of the Transformational Tools and Technologies Project. A multiphysics approach to model heat conduction through the solid geometry is shown to offer significant improvements in wall temperature and film effectiveness prediction accuracy over the standard adiabatic wall approach. Additionally, localized gradient-based grid adaption is analyzed using the …

Analysis Of Ship Airwakes Using Modal Decomposition, Nicholas Zhu

Doctoral Dissertations and Master's Theses

The three-dimensional, unsteady, and turbulent airwake produced by a scaled model of a generic Navy ship (Simple Frigate Shape No. 2) was investigated in a low-speed wind tunnel. Stereoscopic, time-resolved particle image velocimetry (TR-PIV) measurements were made at six different crosswise planes over the flight deck region of the ship model, with and without the effect of a simulated atmospheric boundary layer (ABL).

Spatiotemporal analyses of the TR-PIV measurements were performed using modal decomposition, and the modes were decomposed further based on the frequency contents of their time dynamics. This approach allowed an inspection of the individual scales of the …

A Comparative Study Between 6 Degree-Of-Freedom Trajectory Model And Modified Point Mass Trajectory Model Of Spinning Projectiles, Ange Du

Doctoral Dissertations and Master's Theses

For spinning projectiles, the 6 Degree-of-Freedom model can closely capture their trajectories with high accuracy and details. However, it comes with the drawbacks of long computation time and needing many aerodynamic coefficients which can be hard to obtain. The Modified Point Mass Trajectory Model was introduced as a simplified solution. This work compares them with each other, and with some more conventional methods. A program is developed to simulate and visualize trajectories. With some augmentations, the Modified Point Mass model is able to generate comparable results in most cases, but not including special cases such as when the projectile is …

Comparative Study On The Prediction Of Aerodynamic Characteristics Of Mini - Unmanned Aerial Vehicle With Turbulence Models, Somashekar V, Immanuel Selwyn Raj A

International Journal of Aviation, Aeronautics, and Aerospace

When dealing with CFD simulations the turbulent nature is seen on most of the engineering flows and these flows need to be solved. Reliable and applicable CFD outputs can be obtained from the accurate modelling of the turbulence as it is one of the most vital elements of CFD modelling. The RANS equations are extensively employed to analyse the complex flows over aircraft and for this purpose, a turbulence model is needed for turbulent flow analyses. Compatible turbulence must be chosen for the exact predictions of aircraft aerodynamic characteristics. In this report, numerical analyses of Mini-UAV are done to compare …

Identification Of Wind-Induced Hazard Zones Impacting Uas Bridge Inspection, Jack J. Green, John Mott

International Journal of Aviation, Aeronautics, and Aerospace

Unmanned Aerial Systems (UAS) continue to grow in both popularity and utility within the national airspace system. The use of commercial UAS for civil inspection, specifically that of bridge structures, is becoming commonplace among practitioners and academics alike. The development of an integrated bridge-inspection hazard model provides a way for UAS operators to prepare for and respond to changing environmental conditions that could otherwise prevent a successful UAS flight. The interaction of wind-induced airflow with bridge surfaces creates an aerodynamic wake that can result in hazardous conditions for a UAS platform operating in close proximity. An analysis of this airflow …

Numerical Analysis Of Aerospike Engine Nozzle Performance At Various Truncation Lengths, Sam Dakka Dr, Oliver Dennison

International Journal of Aviation, Aeronautics, and Aerospace

The aerospike engine was first devised in the early 1960s where it provided new means of reaching orbit in a single stage. The paper aimes to demonstrate the viability of the technology by showcasing the increased nozzle thrust efficiency over the conventional bell nozzle. Various truncations were applied to the nozzle and each was subjected to two conditions, an over-expansion and near optimum condition. The nozzle contour was developed using the simple approximation method and was chosen to replicate that of the XRS-2200. This anchored the data, thereby validating the computational fluid dynamics (CFD) simulation. Simulations were completed for at …

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 …

A Model For Inhalation Of Infectious Aerosol Contaminants In An Aircraft Passenger Cabin, Bert A. Silich

International Journal of Aviation, Aeronautics, and Aerospace

Aerosol contamination of an aircraft cabin by infectious passengers is a concern of passengers, aircrew and the aviation industry. This may be especially important during a pandemic, such as COVID-19, where the full extent of aerosol transmission is not well understood. A statistical method to determine the number of infectious passengers on board along with a mathematical model estimating the contaminant concentration of aerosols in the cabin and the number of inhaled infectious particles by passengers is presented. An example is used to demonstrated how the results can be estimated during normal operations and emergency conditions with malfunctions of the …

Aerodynamic Performance Analysis Of Co-Flow Jet Airfoil, C M Vigneswaran, Vishnu Kumar G C

International Journal of Aviation, Aeronautics, and Aerospace

The work in this paper aims to increase the maximum lift coefficient of the airfoil by implementing the co-flow jet concept on NACA 0018 airfoil and also to investigate the performance of co-flow jet (CFJ) airfoil. To conduct numerical solution, RANS equations have been solved for 2D incompressible and unsteady flow using the Spalart-Allmaras turbulence model. The suction surface of the airfoil is modified by placing the injection slot near the leading edge and the suction slot near the trailing edge. A small mass of air is withdrawn into the airfoil suction slot, pressurized by a pumping system located inside …

Albatross And Falcon Inspired Bionic Uav: An Aerodynamic Analysis, Bilji C. Mathew, Sagar K. Sahu, Prantik Dutta, Rushi Savale, Muruga Lal Jeyan Jv Dr.

International Journal of Aviation, Aeronautics, and Aerospace

The drone industry yearns for enhanced aerodynamic performance. In order to achieve this feat, researchers and engineers are trying to mimic the natural flyers due to their aerodynamic optimality. One such flyer, the Albatross is an inspiration for many marine drones due to its planform and aerodynamic efficiency. The wing of the plan form is designed and simulated to study its properties. The Bell-Shaped Lift Distribution is incorporated for higher efficiency and elimination of the total downwash produced in case of an Elliptical Lift Distribution. A blended wing body inspired by the Falcon is used for smoother airflow interactions. Furthermore, …