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Articles 7321 - 7350 of 11125

Full-Text Articles in Engineering

Information Measures For Statistical Orbit Determination, Alinda Kenyana Mashiku Jan 2013

Information Measures For Statistical Orbit Determination, Alinda Kenyana Mashiku

Open Access Dissertations

The current Situational Space Awareness (SSA) is faced with a huge task of tracking the increasing number of space objects. The tracking of space objects requires frequent and accurate monitoring for orbit maintenance and collision avoidance using methods for statistical orbit determination. Statistical orbit determination enables us to obtain estimates of the state and the statistical information of its region of uncertainty given by the probability density function (PDF). As even collision events with very low probability are important, accurate prediction of collisions require the representation of the full PDF of the random orbit state. Through representing the full PDF …

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Gaseous Corrosion In Hard Disk Drive: A Computational Study, Hardik Shah Jan 2013

Gaseous Corrosion In Hard Disk Drive: A Computational Study, Hardik Shah

Mechanical and Aerospace Engineering Theses - Archive

HDD is the largest digitally encoded data storage device. HDD is used to store digital data in data centers, computers and laptops. A typical HDD consists of a casing, an actuator arm, actuator axis, head, platters, power connectors, and jumper pins. The platter is made up of non-magnetic material and is covered by magnetic material, which stores the data. The magnetic heads are mounted on a moving actuator arm to read and write the data. One of the modes of failure of a HDD is corrosion. The parts of the HDD are corroded by coming in contact with the contaminants. …

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Optimal Thickness Distributions Of Aeroelastic Flapping Shells, Bret Stanford, Philip Beran Jan 2013

Optimal Thickness Distributions Of Aeroelastic Flapping Shells, Bret Stanford, Philip Beran

United States Air Force: Publications

The severe weight limitations of flapping wing micro air vehicles necessitates the use of thin flexible wings, which in turn requires an aeroelastic modeling tool for proper numerical characterization. Furthermore, due to the unconventional nature of these vehicles, wing design guidelines for thrust and/or power considerations are not generally available; numerical design optimization then becomes a valuable tool. This work couples a nonlinear shell model to an unsteady vortex lattice solver, and then computes analytical design gradients: the derivative of aerodynamic force/power quantities with respect to a large vector of thickness variables. Gradient-based optimization is then used to locate the …

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Direct Ignition And S-Curve Transition By In Situ Nano-Second Pulsed Discharge In Methane/Oxygen/Helium Counterflow Flame, Wenting Sun, Sang Hee Won, Timothy Ombrello, Campbell Carter, Yiguang Ju Jan 2013

Direct Ignition And S-Curve Transition By In Situ Nano-Second Pulsed Discharge In Methane/Oxygen/Helium Counterflow Flame, Wenting Sun, Sang Hee Won, Timothy Ombrello, Campbell Carter, Yiguang Ju

United States Air Force: Publications

A well-defined plasma assisted combustion system with novel in situ discharge in a counterflow diffusion flame was developed to study the direct coupling kinetic effect of non-equilibrium plasma on flame ignition and extinction. A uniform discharge was generated between the burner nozzles by placing porous metal electrodes at the nozzle exits. The ignition and extinction characteristics of CH4/O2/He diffusion flames were investigated by measuring excited OH* and OH PLIF, at constant strain rates and O2 mole fraction on the oxidizer side while changing the fuel mole fraction. It was found that ignition and extinction occurred with an abrupt change of …

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Libration Point Orbits Near Small Bodies In The Elliptic Restricted Three-Body Problem, Bharat Mahajan Jan 2013

Libration Point Orbits Near Small Bodies In The Elliptic Restricted Three-Body Problem, Bharat Mahajan

Masters Theses

"In this study, the feasibility of using libration point orbits to explore small solar system bodies, including asteroids and comets, is considered. A novel design for a small body mission is proposed that makes use of libration point orbits as "parking" orbits. In considering a human exploration mission to asteroids or comets, these "parking" orbits may provide benefits including a safe vantage point for staging/observation, reduced perturbation effects from the nonuniform gravitational field of the body, fewer communication blackouts, ease of guidance and control of a lander on the surface, etc. Because small solar system bodies have extremely low mass …

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Manual Modification And Plasma Exposure Of Boron Nitride Ceramic To Study Hall Effect Thruster Plasma Channel Material Erosion, Alexander J. Satonik Jan 2013

Manual Modification And Plasma Exposure Of Boron Nitride Ceramic To Study Hall Effect Thruster Plasma Channel Material Erosion, Alexander J. Satonik

Masters Theses

"Worn Hall effect thrusters (HET) show a variety of unique microstructures and elemental compositions in the boron nitride thruster channel walls. Worn thruster channels are typically created by running test thrusters in vacuum chambers for hundreds of hours. Studies were undertaken to manually modify samples of boron nitride without the use of a hall effect thruster. Samples were manually abraded with an abrasive blaster and sandpaper, in addition to a vacuum heater. Some of these samples were further exposed to a xenon plasma in a magnetron sputter device. Sandpaper and abrasive blaster tests were used to modify surface roughness values …

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A Computational Study Of Driven Micro-Cavities In Supersonic Flat Plate Flow, Thomas Ryan Rehmeier Jan 2013

A Computational Study Of Driven Micro-Cavities In Supersonic Flat Plate Flow, Thomas Ryan Rehmeier

Masters Theses

"Driven micro-cavities embedded in the wall beneath turbulent supersonic boundary layers are analyzed using two-dimensional computational fluid dynamics. This concept is a passive flow control technique in which very small cavities formed by arrays of thin vertical walls are oriented transverse to the flow direction and underlie the boundary layer. The purpose is to reduce or eliminate skin friction drag. Various micro-cavity configurations were analyzed at locations (0.1 m and 1 m) downstream of the leading edges of flat plates, for free-stream Mach numbers of 1.2, 2.0, and 3.0. Results focus on net drag reduction achieved, cavity flow-field effects, perforation …

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Robustness Of A Derivative-Free Adaptive Control Law In The Presence Of Unmodeled Dynamics, Tansel Yucelen, Anthony J. Calise Jan 2013

Robustness Of A Derivative-Free Adaptive Control Law In The Presence Of Unmodeled Dynamics, Tansel Yucelen, Anthony J. Calise

Mechanical and Aerospace Engineering Faculty Research & Creative Works

Although adaptive control theory offers mathematical tools to achieve required system performance without excessive dependence on modeling, its application to safety-critical systems can be limited by the presence of unmodeled dynamics. This paper examines the robustness to unmodeled dynamics of a recently developed derivative-free adaptive control law. In contrast to derivative-based adaptive laws it is shown, using a Lyapunov-Krasovskii functional, that robustness to unmodeled dynamics is improved by increasing the adaptation gain. This is accomplished by including a bias term in the set of basic functions employed by the adaptive control law. It is shown that derivative-based adaptive laws do …

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Hybrid Protocols For Maintaining Connectivity Of Multiagent Systems, Gerardo De La Torre, Tansel Yucelen, Eric N. Johnson Jan 2013

Hybrid Protocols For Maintaining Connectivity Of Multiagent Systems, Gerardo De La Torre, Tansel Yucelen, Eric N. Johnson

Mechanical and Aerospace Engineering Faculty Research & Creative Works

This paper focuses on a new connectivity control architecture for networked multiagent systems based on hybrid protocols. Specifically, for a group of agents subject to Δ-disk proximity graphs, we consider the consensus problem while preserving connectedness with a priori given bounds on the control inputs. The bounds on the control inputs are shown not to depend on potential functions or system states. Instead, the bounds are user selected continuous functions. By using the proposed framework, we show that the maximum distance among neighboring agents decreases strictly, and hence the connectivity problem is solved while satisfying the consensus objective. © 2013 …

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Effect Of Stitch Density On Tensile Properties And Damage Mechanisms Of Stitched Carbon/Epoxy Composites, Arief Yudhanto, Naoyuki Watanabe, Yutaka Iwahori, Hikaru Hoshi Jan 2013

Effect Of Stitch Density On Tensile Properties And Damage Mechanisms Of Stitched Carbon/Epoxy Composites, Arief Yudhanto, Naoyuki Watanabe, Yutaka Iwahori, Hikaru Hoshi

Mechanical and Aerospace Engineering Faculty Research & Creative Works

Experimental investigation is performed to study tensile properties, damage initiation and development in stitched carbon/epoxy composites subjected to tensile loading. T800SC-24kf dry preforms with tow orientation of [+45/90/-45/02/+45/902/-45/0]s are stitched using 200 denier Vectran® thread. Modified-lock stitch pattern is adopted, and stitch density is varied, viz. moderate density (stitched 6 x 6: stitch density = 2.8 cm-2) and high density (stitched 3 x 3: stitch density = 11.1 cm-2). The stitched preforms are then infiltrated by epoxy XNR/H6813 using resin transfer molding process. Tensile test is conducted to obtain in-plane mechanical properties (tensile strength, failure strain, tensile modulus and Poisson's …

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Damage Characterization And Analytical Modeling Of Quasi-Statically Indented Graphite/Epoxy-Honeycomb Core Composite Sandwich Stru, Abhendra K. Singh Jan 2013

Damage Characterization And Analytical Modeling Of Quasi-Statically Indented Graphite/Epoxy-Honeycomb Core Composite Sandwich Stru, Abhendra K. Singh

Mechanical and Aerospace Engineering - Dissertations

The research conducted for this dissertation focused on understanding the nature and extent of barely visible impact damage (BVID) in composite sandwich structures. This was part of a larger research effort that included studies on the influence of BVID on the compressive strengths and failure modes of composite sandwich structures. In this dissertation, the nature and extent of BVID is studied in aluminum honeycomb core sandwich panels with eight and sixteen ply, quasi-isotropic, graphite/epoxy face sheets. The damage in the sandwich structure is created quasi-statically using spherical indentors of two different sizes. Apart from the face sheet thickness and indentor …

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Discussion Of Christine C. Shepard, Vera N. Agostini, Ben Gilmer, Tashya Allen, Jeff Stone, William Brooks And Michael W. Beck. Reply: Evaluating Alternative Future Sea-Level Rise Scenarios, Natural Hazards, 2012 Doi:10.1007/S11069-012-0160-2, A. Boretti Jan 2013

Discussion Of Christine C. Shepard, Vera N. Agostini, Ben Gilmer, Tashya Allen, Jeff Stone, William Brooks And Michael W. Beck. Reply: Evaluating Alternative Future Sea-Level Rise Scenarios, Natural Hazards, 2012 Doi:10.1007/S11069-012-0160-2, A. Boretti

Mechanical and Aerospace Engineering Faculty Research & Creative Works

No abstract provided.

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Neuropredictive Control And Trajectory Generation For Slung Load Systems, Gerardo De La Torre, Eric N. Johnson, Tansel Yucelen Jan 2013

Neuropredictive Control And Trajectory Generation For Slung Load Systems, Gerardo De La Torre, Eric N. Johnson, Tansel Yucelen

Mechanical and Aerospace Engineering Faculty Research & Creative Works

This paper presents a neuropredictive trajectory generation architecture for slung load systems. The presented architecture integrates the real-time trajectory generation method with a system uncertainty identifying neural network. It is shown that the effect of system uncertainty on a model predictive control approach can be mitigated by the use of neural networks. A numerical example of an uncertain slung load system is shown to demonstrate the effectiveness of the presented framework.

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Separate-Channel Integrated Guidance And Autopilot For Automatic Path-Following, Takeshi Yamasaki, S. N. Balakrishnan, Hiroyuki Takano Jan 2013

Separate-Channel Integrated Guidance And Autopilot For Automatic Path-Following, Takeshi Yamasaki, S. N. Balakrishnan, Hiroyuki Takano

Mechanical and Aerospace Engineering Faculty Research & Creative Works

An integrated guidance and autopilot scheme for a path-following uninhabited aerial vehicle is presented in this study. A fixed-wing aircraft usually performs a bank-to-turn maneuver to change its flight direction. The novel approach presented here, however, assumes that each of the three channels of the integrated guidance and autopilot can be independently designed. This concept makes the design process simple. A virtual target moving on the prespecified path for the uninhabited aerial vehicle is introduced to facilitate the algorithm development. A first-/ second order sliding structure with a second order sliding mode and a high-order sliding mode differentiator for the …

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Constraint Enforcement Methods For Command Governor Based Adaptive Control Of Uncertain Dynamical Systems, Simon P. Schatz, Tansel Yucelen, Eric N. Johnsony, Florian Holzapfelz Jan 2013

Constraint Enforcement Methods For Command Governor Based Adaptive Control Of Uncertain Dynamical Systems, Simon P. Schatz, Tansel Yucelen, Eric N. Johnsony, Florian Holzapfelz

Mechanical and Aerospace Engineering Faculty Research & Creative Works

Recently, research has been conducted in order to improve the transient behavior of adaptively controlled uncertain nonlinear dynamical systems. In this paper, an adaptive control architecture is extended in order to achieve predictable transient performance in the presence of state constraints. The methodology at hand is based on a robust command governor framework, which is a dynamical system adjusting the trajectory of a given command in order to track a certain desired closed-loop reference model both in transient time and steady-state. Specifically, the command, which is applied on the reference model and the actual system, is changed by the command …

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Non-Equilibrium Pressure Control Of The Height Of A Large-Scale, Ground-Coupled, Rotating Fluid Column, R. L. Ash, I. R. Zardadhkan Jan 2013

Non-Equilibrium Pressure Control Of The Height Of A Large-Scale, Ground-Coupled, Rotating Fluid Column, R. L. Ash, I. R. Zardadhkan

Mechanical & Aerospace Engineering Faculty Publications

When a ground-coupled, rotating fluid column is modeled incorporating non-equilibrium pressure forces in the Navier-Stokes equations, a new exact solution results. The solution has been obtained in a similar manner to the classical equilibrium solution. Unlike the infinite-height, classical solution, the non-equilibrium pressure solution yields a ground-coupled rotating fluid column of finite height. A viscous, non-equilibrium Rankine vortex velocity distribution, developed previously, was used to demonstrate how the viscous and non-equilibrium pressure gradient forces, arising in the vicinity of the velocity gradient discontinuity that is present in the classical Rankine vortex model, effectively isolate the rotating central fluid column from …

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Modelling And Configuration Control Of Wing-Shaped Bi-Stable Piezoelectric Composites Under Aerodynamic Loads, Andres F. Arrieta, Onur Bilgen, Michael I. Friswell, Paolo Ermanni Jan 2013

Modelling And Configuration Control Of Wing-Shaped Bi-Stable Piezoelectric Composites Under Aerodynamic Loads, Andres F. Arrieta, Onur Bilgen, Michael I. Friswell, Paolo Ermanni

Mechanical & Aerospace Engineering Faculty Publications

Bi-stable composites have been considered for morphing applications thanks to their ability to hold two statically stable shapes with no energy consumption. In this paper, the modelling of the dynamic response of cantilevered wing-shaped bi-stable composites is presented. To this end, an analytical model approximating the dynamic response about each statically stable shape of wing-shaped bi-stable composites is derived. Theoretical modal properties are obtained to attain or stabilise a desired configuration following a previously introduced resonant control strategy. The resonant control technique is evaluated for a wing-shaped bi-stable composite subject to aerodynamic loads. Wind tunnel experiments are conducted on a …

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Numerical Study Of Pressure Fluctuations Due To A Mach 6 Turbulent Boundary Layer, Lian Duan, Meelan M. Choudhari Jan 2013

Numerical Study Of Pressure Fluctuations Due To A Mach 6 Turbulent Boundary Layer, Lian Duan, Meelan M. Choudhari

Mechanical and Aerospace Engineering Faculty Research & Creative Works

Direct numerical simulations (DNS) are used to examine the pressure fluctuations generated by a Mach 6 turbulent boundary layer with nominal freestream Mach number of 6 and Reynolds number of Reτ ≈ 464. The emphasis is on comparing the primarily vortical pressure signal at the wall with the acoustic freestream signal under higher Mach number conditions. Moreover, the Mach-number dependence of pressure signals is demonstrated by comparing the current results with those of a supersonic boundary layer at Mach 2.5 and Reτ ≈ 510. It is found that the freestream pressure intensity exhibits a strong Mach number dependence, irrespective of …

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Prediction Of Foreign Object Debris/Damage Fod Type Based In Human Factors For Aeronautics Using Logistic Regression Model, David Ricardo Romo Jan 2013

Prediction Of Foreign Object Debris/Damage Fod Type Based In Human Factors For Aeronautics Using Logistic Regression Model, David Ricardo Romo

Open Access Theses & Dissertations

Foreign Object Debris/Damage (FOD) has been an issue for military and commercial aircraft manufacturers since the early ages of aviation and aerospace. Currently, aerospace is growing rapidly and the chances of FOD presence are growing as well. One of the principal causes in manufacturing is the human error. The cost associated with human error in commercial and military aircrafts is approximately accountable for 4 billion dollars per year. This problem is currently addressed with prevention programs, elimination techniques, and designation of FOD areas, controlled access, restrictions of personal items entering designated areas, tool accountability, and the use of technology such …

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Proceedings Of The First International Conference On Smarandache Multispace & Multistructures, Florentin Smarandache, Linfan Mao Jan 2013

Proceedings Of The First International Conference On Smarandache Multispace & Multistructures, Florentin Smarandache, Linfan Mao

Branch Mathematics and Statistics Faculty and Staff Publications

In recent decades, Smarandache’s notions of multispace and multistructure were widely spread and have shown much importance in sciences around the world. Organizedby Prof.Linfan Mao, a professional conference on multispaces and multistructures, named the First International Conference on Smarandache Multispace and Multistructure was held in Beijing University of Civil Engineering and Architecture of P. R. China on June 28-30, 2013, which was announced by American Mathematical Society in advance.

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Bio-Inspired Cooperative Optimal Trajectory Planning For Autonomous Vehicles, Charles Remeikas Jan 2013

Bio-Inspired Cooperative Optimal Trajectory Planning For Autonomous Vehicles, Charles Remeikas

Electronic Theses and Dissertations

With the recent trend for systems to be more and more autonomous, there is a growing need for cooperative trajectory planning. Applications that can be considered as cooperative systems such as surveying, formation flight, and traffic control need a method that can rapidly produce trajectories while considering all of the constraints on the system. Currently most of the existing methods to handle cooperative control are based around either simple dynamics and/or on the assumption that all vehicles have homogeneous properties. In reality, typical autonomous systems will have heterogeneous, nonlinear dynamics while also being subject to extreme constraints on certain state …

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Chemoelastoplastic Analysis Of A Copper-Graded Silicon Nanorod For Lithium-Ion Battery Anode Application, Chao Ji Jan 2013

Chemoelastoplastic Analysis Of A Copper-Graded Silicon Nanorod For Lithium-Ion Battery Anode Application, Chao Ji

Mechanical and Aerospace Engineering Theses - Archive

Lithium-ion batteries are currently widely used in electronics, electrical vehicles and other devices/machines. Along with the mounting demand for much improved performance in these developing technological fields, silicon was recognized to possess much higher energy capacity when used as an anode than graphite that is currently used. However, there occurs colossal volume expansion of silicon anode during the lithiation process. The material consequently suffers enormous stresses, especially, at the interface with a current collector, which deteriorate the device quickly during cycling. To prevent the active material (Si) from falling off from a current collector, nanoengineering strategies have been suggested, including …

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Application Of Phase Change Material In Sustainable Cooling Of Data Centers, Nikhil Dhiman Jan 2013

Application Of Phase Change Material In Sustainable Cooling Of Data Centers, Nikhil Dhiman

Mechanical and Aerospace Engineering Theses - Archive

The ever increasing information technology heat load and data center cooling energy are the main reasons to investigate the performance of microencapsulated phase change slurry over other heat transfer fluids. In recent years, more effort is being made on the development of a new technique to use the phase change materials as pump-able heat transfer fluid and as heat storage system.Microencapsulated phase change slurry is dispersion where the phase change material, microencapsulated by a polymeric capsule, is dispersed in water. Compared to water, these new fluids have a higher heat capacity during phase change and a possible enhancement, as a …

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Thermal Management Method For Foil Bearings In Turbine Hot Section, Tejas Devidas Patil Jan 2013

Thermal Management Method For Foil Bearings In Turbine Hot Section, Tejas Devidas Patil

Mechanical and Aerospace Engineering Theses - Archive

Recently, Air Foil Bearings (AFB) are gaining higher industrial acceptance in micro-turbo machinery. AFB show high speed operating capability and environmental friendly operation in comparison to rolling element bearings. Utilization of ambient air as a lubricant eliminates maintenance of a pressurized oil lubricating system. AFBs are therefore a feasible alternative to oil lubricated bearings in small machines. High speed operation results in thermal management issues which can be solved through a suitable cooling mechanism. Axial cooling by passing air through bearing support structure (called bump foils) is the most commonly used. In this method, cooling is achieved in the heat …

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Immersion Cooling Of High End Data Center Server And Validation Through Experiments, Harsh Patel Jan 2013

Immersion Cooling Of High End Data Center Server And Validation Through Experiments, Harsh Patel

Mechanical and Aerospace Engineering Theses - Archive

Despite recent improvements in data center cooling efficiency such as hot and cold aisle and air side economizer, air cooling may not have the capacity to cool high end racks such as from IBM's NetBAY42 (150Kw and above). Increasing computer capabilities in data center has resulted in increase in rack power density per square ft as indicated by the latest uptime. The cooling of such high powered servers and corresponding racks poses a significant challenge to thermal engineers.The use of immersion cooling is novel approach for data center cooling. In this study after some modification high powered server is fully …

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Vision-Based Sensing And Optimal Control For Low-Cost And Small Satellite Platforms, Bradley Sease Jan 2013

Vision-Based Sensing And Optimal Control For Low-Cost And Small Satellite Platforms, Bradley Sease

Electronic Theses and Dissertations

Current trends in spacecraft are leading to smaller, more inexpensive options whenever possible. This shift has been primarily pursued for the opportunity to open a new frontier for technologies with a small financial obligation. Limited power, processing, pointing, and communication capabilities are all common issues which must be considered when miniaturizing systems and implementing low-cost components. This thesis addresses some of these concerns by applying two methods, in attitude estimation and control. Additionally, these methods are not restricted to only small, inexpensive satellites, but offer a benefit to large-scale spacecraft as well. First, star cameras are examined for the tendency …

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Mission Analysis For Pico-Scale Satellite Based Dust Detection In Low Earth Orbits, Jacob Belli Jan 2013

Mission Analysis For Pico-Scale Satellite Based Dust Detection In Low Earth Orbits, Jacob Belli

Electronic Theses and Dissertations

A conceptual dust detection mission, KnightSat III, using pico-scale satellites is analyzed. The purpose of the proposed KnightSat III mission is to aid in the determination of the size, mass, distribution, and number of dust particles in low earth orbits through a low cost and flexible satellite or a formation of satellites equipped with a new dust detector. The analysis of a single satellite mission with an on-board dust detector is described; though this analysis can easily be extended to a formation of pico-scale satellites. Many design aspects of the mission are discussed, including orbit analysis, power management, attitude determination …

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A Numerical Study Of Incompressible Fluid Flow Over A Forward Facing Step At Various Grades, Peter Andrew Martinez Jan 2013

A Numerical Study Of Incompressible Fluid Flow Over A Forward Facing Step At Various Grades, Peter Andrew Martinez

Mechanical and Aerospace Engineering Theses - Archive

The study of the effect of natural forces on hydraulic structures is of great concern for the accurate prediction of when a design could be at risk of failure. In recent times the use of the shallow water equations to predict the behavior of the free surface for flow over a step has proven inaccurate because only a hydrostatic pressure distribution is considered. One of the phenomena that will not be accounted for with the shallow water equations in such a setup is the formulation of undular bore type waves on the surface. In order for a more accurate representation …

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Design, Fabrication And Test Of Surface Tension-Driven Microboats And Thermally Oscillatory Bubble-Propelled Microsubmarines, Lei Qiao Jan 2013

Design, Fabrication And Test Of Surface Tension-Driven Microboats And Thermally Oscillatory Bubble-Propelled Microsubmarines, Lei Qiao

Mechanical and Aerospace Engineering Dissertations - Archive

In this work, we develop microboats and microsubmarines, which are capable of moving on and under water, respectively. The microboat is propelled due to the difference between surface tensions around stern and bow. This difference is generated by releasing a liquid with lower surface tension than water from the stern. We explore both horizontal and vertical motions of the microboats through a combination of experimental and theoretical investigations. It has a length of 8 mm and weight of 20 mg with the highest speed of 25 cm/s and travel distance of 85 cm. Moreover, we design, fabricate and test microboats …

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Experimental Characterization Of Roughness And Flow Injection Effects In A High Reynolds Number Turbulent Channel, Mark A. Miller Jan 2013

Experimental Characterization Of Roughness And Flow Injection Effects In A High Reynolds Number Turbulent Channel, Mark A. Miller

Theses and Dissertations--Mechanical and Aerospace Engineering

A turbulent channel flow was used to study the scaling of the combined effects of roughness and flow injection on the mean flow and turbulence statistics of turbulent plane Poiseuille flow. It was found that the additional momentum injected through the rough surface acted primarily to enhance the roughness effects and, with respect to the mean flow, blowing produced similar mean flow effects as increasing the roughness height. This was not found to hold for the turbulence statistics, as a departure from Townsend’s hypothesis was seen. Instead, the resulting outer-scaled streamwise Reynolds stress for cases with roughness and blowing deviated …

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