Master of Science / Department of Geology / Abdelmoneam Raef / In this study, laboratory measurements of ultrasonic frequency P- and S-wave velocities were collected and analyzed from two sets of cores. The first set is from a near surface study in southeastern Kansas, and the second set was from the deep subsurface and obtained from a newly drilled well (Wellington KGS 1-32) in Sumner County, KS. Ultrasonic velocities acquired from the second set of cores were then compared with in situ sonic and dipole sonic frequencies of P- and S-waves from well logs. Well log data, core data, and ultrasonic velocity measurements were integrated for Gassmann fluid replacement modeling. The understanding of the velocity and elastic moduli variations at ultrasonic frequencies, along with the comparison of well log velocities can potentially provide improved understanding to establish a beneficial calibration relationship. It could also allow for estimation of shear wave velocities for wells lacking dipole sonic log data. The ability to utilize cost-effective ultrasonic measurements of velocities and elastic moduli in the laboratory, for fluid replacement modeling (Gassmann) in CO[subscript]2-sequestration, as well as, enhanced oil recovery (EOR) projects, would be a significant advance. Potential alternative use of ultrasonic velocities for determining the effects of fluid replacement using Gassmann modeling, when log data is lacking, is an ongoing effort. In this study, the fluid replacement modeling is executed based on sonic and dipole sonic P- and S-wave velocities and compared with results from theoretical modeling. The significance of this work lies in the potential of establishing a calibration relationship for the representative lithofacies of the carbon geosequestration target zone of the Wellington KGS 1-32 well in Sumner County, and enabling the use of ultrasonic measurements of body wave velocities and elastic moduli in Gassmann fluid replacement modeling. This work, when integrated with continuing effort in mapping lithofacies of the Arbuckle and Mississippian groups, would potentially be of great importance to fluid flow simulation efforts and time-lapse seismic monitoring. This study will utilize Gassmann modeling and a range of measurements and data, which include: well logs and ultrasonic laboratory P- and S-wave measurements and core analysis data.

The use of non-destructive testing (NDT) methods was needed for the conservation studies of historic timber structures. The aim of this study was to develop combined use of ultrasonic pulse velocity (UPV) measurements and infrared (IR) thermography, together with visual analyses for soundness assessment of timber. An important timber structure in Ankara, Aslanhane Mosque and traditional timber dwellings, in AyaS and istiklal District were selected for in-situ analyses. Representative laboratory samples such as mud brick, fired brick, mud mortar, mud plaster, lime plaster, historic timbers of different species and some new timbers were used for analyses in the laboratory to develop reference data for in-situ analyses. This study has shown that direct and indirect UPV measurements taken parallel to fiber direction were good at estimating the soundness of timber elements. UPV measurements taken from timber samples were affected by atmospheric humidity, at which the timber was in equilibrium with or by its water content, cuts of timber and type of species. Quantitative Infrared thermography (QIRT) was good at soundness assessment and defect inspection of timber. The study showed that, the even or heterogeneous distribution of surface temperatures, different thermal inertia characteristics, reflected by the rates of heating and cooling of materials and their ratios to sound timber were good parameters to assess the state of deterioration of timber elements, dampness problems and the compatibility of neighbouring materials with timber. The joint use of QIRT and UPV methods combined with laboratory data has enhanced the accuracy and effectiveness of the survey.

No description available.

The purpose of the study was to evaluate the merits of the DiscRotor concept that combine the features of a retractable rotor system for vertical take-off and landing (VTOL) with an integral, circular wing for high-speed flight. Tests were conducted to generate basic aerodynamic characteristics of the DiscRotor in hover and in fixed-wing flight. To assess the DiscRotor during hover, small scale tests were conducted on a 3ft diameter rotor without the presence of a fuselage. A "hover rig" was constructed capable of rotating the model rotor at speeds up to 3,500 RPM to reach tip speeds of 500fps. Thrust and torque generated by the rotating model were measured via a two-component load cell, and time averaged values were obtained for various speeds and pitch angles. It has been shown that the DiscRotor will perform well in hover. Ground Effects in hover were examined by simulating the ground with a movable, solid wall. The thrust was found to increase by 50% compared to the ground-independent case. Pressure distributions were measured on the ground and disc surfaces. Velocity measurements examined the flow field downstream of the rotor by traversing a seven hole velocity probe. A wake behind the rotor was shown to contract due to a low pressure region that develops downstream of the disc. Wind tunnel experimentation was also performed to examine the fixed wing flight of the DiscRotor. These experiments were performed in the VA Tech 6â X6â Stability Tunnel. A model of the fuselage and a circular wing was fabricated based upon an initial sizing study completed by our partners at Boeing. Forces were directly measured via a six degree of freedom load cell, or balance, for free stream velocities up to 200fps. Reynolds numbers of 2 and 0.5 million have been investigated for multiple angles of attack. Low lift-to-drag ratios were found placing high power requirements for the DiscRotor during fixed-wing flight. By traversing a seven-hole velocity probe, velocities in a 2-D grid perpendicular to the flow were measured on the model. The strengths of shed vortices from the model were calculated. A method to improve fixed-wing performance was considered where two blades were extended from the disc. An increase of 0.17 in the CL was measured due to the interaction between the disc and blades. This research utilized a wide range of experiments, with the aim of generating basic aerodynamic characteristics of the DiscRotor. A substantial amount of quantitative data was collected that could not be included in this document. Results aided in the initial designs of this aircraft for the purpose of evaluating the merit of the DiscRotor concept. / Master of Science

No description available.

The present study proposes to use a Conrad probe for transient growth study by measuring the two-dimensional velocity behind an array of roughness elements in the Blasius boundary layer. A look-up table approach is proposed to increase the accuracy of the data reduction process at low velocities, based on the results of the calibration performed in a round jet. A velocity correction method is proposed to minimize the errors due to high velocity shear and wall-proximity in the Blasius boundary layer by comparing Conrad probe results to previous hot-wire data. Measurements of the steamwise velocity perturbation obtained with the Conrad probe agree with previous studies. The measured spanwise perturbation confirms the transport process suggested by simulation. The results show that the perturbation amplitude increases by increasing both the freestream velocity and roughness elements height. However, the mechanism for changing the perturbation amplitude of influence differs for these two parameters.

The present study proposes to use a Conrad probe for transient growth study by measuring the two-dimensional velocity behind an array of roughness elements in the Blasius boundary layer. A look-up table approach is proposed to increase the accuracy of the data reduction process at low velocities, based on the results of the calibration performed in a round jet. A velocity correction method is proposed to minimize the errors due to high velocity shear and wall-proximity in the Blasius boundary layer by comparing Conrad probe results to previous hot-wire data. Measurements of the steamwise velocity perturbation obtained with the Conrad probe agree with previous studies. The measured spanwise perturbation confirms the transport process suggested by simulation. The results show that the perturbation amplitude increases by increasing both the freestream velocity and roughness elements height. However, the mechanism for changing the perturbation amplitude of influence differs for these two parameters.

Behavior of particles in buoyancy driven turbulent flow at Ra ≈ 10º is investigated experimentally. The volume fraction of the particles is low enough for the inter particle influence to be neglected, the mass loading of particle is low enough that the turbulence as not modified, and the particles Reynolds numbers (Re p ) st are small enough that the wake effect can be neglected. The buoyancy driven turbulent flow is created by maintaining an unstable density difference, using NaCl dissolved in water, across the ends of a long vertical tube. There is no mean flow and the turbulence is axially homogeneous. A method for uniform introduction of the particles was devised. Glass particles (S.G=2.4-2.5) of different diameter ranges (50-400 µm) are introduced into this flow. The sizes of particles considered are less than the Kolmogrov length scale corresponding to the turbulence level. The turbulence intensity level was varied in order to match its characteristic time and velocity scale to those of the particles. The ratio of the timescales, the Stokes number; is in the range (0.01-0.55); Stokes number is defined as a ratio of the viscous relaxation time of the particle and a turbulent time scale, and represents the effect of the particle inertia in the interaction with the turbulence, Stk =τp/τk. Another important non-dimensional parameter is the velocity ratio, the k ratio of the particle settling velocity in still fluid to a characteristic turbulence velocity. The flow field is illuminated by a continuous Argon-ion laser and a PHOTRON high- speed digital camera is used for imaging. The raw images are processed to evaluate particle centers followed by their velocity measurements. The objective of the experiment is to check for the effect of the turbulent flow on the sedimentation rate of the heavy particles. This sedimentation rate is compared with the settling velocity obtained in still water. It is expected that within a certain range of Stokes numbers and velocity ratios the sedimentation rate would be substantially changed, and the spatial concentration distribution of the particles may become patchy implying that turbulence may actually inhibit rather than enhance mixing of particles. By varying the turbulence level and particle mean diameter we achieved a set of values for the particle parameters, namely St k. ≈ 0.01, 0.1, 0.14, 0.55 and velocity ratios[[Wp ] St]]≈ 0.2, .0, 0.5, 2.25 respectively. The w rms velocity ratio [[Wp ] St /wf defined as a ratio between the article terminal velocity [Wp ] St and a suitable flow velocity scale; it is a measure of the residence time of the particle in an eddy, in eddy turnover time units. In this study we have considered the turbulence r.m.s velocity for the flow velocity scale.The particle Reynolds number (Re p)st corresponding to these 4 cases were 0.2, 31.5, 4.0, 31.5. Some preliminary quantitative measurements were made only for the 150-200 µm particles and turbulence level w rms ≈ 4.0 cm/s,corresponding to Stk ≈0.14 [[Wp ] St] = 0.5. A quantitative picture was obtained for the other cases. Streak pictures for these four different groups of particles revealed that Stk and the velocity ratio [[Wp ] St ] were important in influencing the particle- w rms turbulence interaction not the Stk alone. The r.m.s velocity fluctuations of particles in both the lateral (utp) and vertical direction (wtp) measured were found to be different from those obtained in still-water case.(For equations, pl see the pdf file)

The condition of no relative velocity of fluid past solid is termed as ‘no-slip boundary condition’. This condition is a general observation in fluid mechanics. However, several research groups have recently reported slip of water for surfaces with water repelling chemistry (referred to as hydrophobic surfaces). The effect has been attributed to disruption of H-bonding network of water molecules at such surfaces and resulting nucleation of dissolved gases and even reduced water density locally in absence of dissolved air. Slip of water on hydrophobic surfaces has been demonstrated to get amplified by high degree of roughness and patterning. Trapping of air in the surface asperities has been cited as the possible reason. The present work focuses on the study of effect of surface chemistry and roughness on flow behavior close to solid surfaces. Superhydrophobic surfaces have been generated by novel methods and wet-etching has been used to generate well-defined patterns on silicon surfaces. For flow characterisation, a micrometre resolution Particle Image Velocimetry (micro-PIV) facility has been developed and flow measurements have been carried out with a spatial resolution of less than 4 µm. It has been found from the experiments that flow of water on smooth surfaces, with or without chemical modification, conforms to the no-slip within the resolution limits of experiments. Deviation is observed in case of rough and patterned hydrophobic surfaces, possibly because of trapped air in asperities. Total Internal Reflection experiments, used to visualise the air pockets, confirmed the trapping of air at asperities. Diffusion of air out of the crevices seems to be the limiting factor for the utility of these surfaces in under-water applications.

Particle Image Velocimetry (PIV) is a powerful technique to measure the velocity at many points in a flow simultaneously by performing correlation analysis on images of particles being transported by the flow. These images are acquired by illuminating the flow with two light pulses so that each particle appears once on each image. <p> The spatial resolution is an important parameter of this measuring system since it determines its ability to resolve features of interest in the flow. The super-resolution technique maximises the spatial resolution by augmenting the PIV analysis with a second pass that identifies specific particles and measures the distance between them. <p> The accuracy of the procedure depends on both the success with which the proper pairings are identified and the accuracy with which their centre-to-centre distance can be measured. This study presents an analysis of both the systematic uncertainty and random uncertainty associated with this process. The uncertainty is analysed as a function of several key parameters that define the quality of the image. The uncertainty analysis is performed by preparing 4000 member ensembles of simulated images with specific setpoints of each parameter. <p> It is shown that the systematic uncertainty is negligible compared to the random uncertainty for all conditions tested. Also, the image contrast and the selection of a threshold for the particle search are the most critical parameters influencing both success rate and uncertainty. It is also shown that high image intensities still yield accurate results. The search radius used by the super-resolution algorithm is shown to be a critical parameter also. By increasing the search radius, the success rate can be increased although this is accompanied by an increase in random uncertainty.