In the past, research into Short Takeoff and Landing aircraft has led to the investigation of the coupling of a Circulation Control Wing and Upper Surface Blowing engine. The Circulation Control Wing entrains the flow of the engine to be deflected downward such that a component of the thrust is now in the vertical direction. The unfortunate consequence of the Upper Surface Blowing engine is the poor cruise performance due to scrub drag. Cal Poly's research into a Cruise Efficient Short Takeoff and Landing Aircraft offers a solution by pylon mounting over the wing engines. Analysis shows that the engine thrust is still deflected downward resulting in very high lift coefficients above 6.6. In the culmination of this project Cal Poly would like to find a correlation between the location of the engine and the deflection angle of the thrust. The results of this study show some engine deflection for an over the wing engine. The configurations explored were able to provide 3°-8.5° of deflection. The deflection falls short of the results by previous static and wind tunnel tests of upper surface blowing engines. The results show that the closer to the wing and further forward the engine is located the more engine deflection will be seen. This paper explores the trends of coupling an over the wing engine with a circulation control wing as well as compare the results to the idealized claims of previous experiments.

This project examined the effect of Gurney flaps on a 2D, 2-ft chord NACA 0036 airfoil in the Cal Poly 3’x4’ low speed wind tunnel at 25 m/s. It also covered the numerical simulation of the experiment in computational fluid dynamics (CFD). During the study, problems with the wind tunnel data were seen. After a careful diagnosis, the problem was traced to dirty flow conditioners which were subsequently replaced. Five Gurney flaps at 1, 2, 3, 4, and 5% of the chord were tested. The Gurney flaps had the effect of eliminating the lift reversal effect and lowering the profile drag at low angles of attack, ranging from 4-27%. The optimal Gurney flap appeared to be 2% of the chord. CFD modeling of the problem had limited success, with the best results coming from Mentor’s k-w SST turbulence model. This model reproduced the non-linear lift curve, and captured the trend in rising drag fairly well, but failed to predict the correct point of separation. Attempts to model the Gurney flap in CFD were unsuccessful.

In this paper, an array of converging-diverging nozzles in parallel is designed to create a highly turbulent, sufficiently mixed flow for the study of turbulent-compressibility effects and assist in the ongoing work of oblique detonation wave (ODW) research. Several nozzle array candidates were designed with varying numbers of nozzles and nozzle sizes and evaluated using computational fluid dynamics to determine which candidate produced the most viable conditions for investigating turbulent compressibility effects. Conditions and design restrictions of the nozzle arrays were tailored to the conditions set in the Hypersonic Wind Tunnel, which is located at the Propulsion and Energy Research Lab at the University of Central Florida.

The objective of this study is to refine the understanding of micro-fluidics subject to micro-gravity in an attempt to support future space exploration efforts. A combination of experimental and numerical approaches were utilized to build a validated assessment approach. A quasi-pore geometry, inspired by CT scans of rat bones, was used in lieu of human bone structures. A quasi-1D assessment of the conservation of momentum was used to identify the dominant forces acting on the fluid at the operating length-scales. The dominant forces were surface tension, gravity, and shear stress. Experiments were conducted to visualize the flow moving through the quasi-pore geometry. Computational Fluid Dynamics (CFD) was used to create a corresponding model of the experiments in order to illicit further insight. The CFD models were validated by using micro-fluidic experiments. Once validated, the CFD model was also used to study micro-fluids in micro-gravity conditions. The results showed that gravity has a significant effect on the flow pattern of fluids through micro-fluidic porous features. The results can be correlated to the fluid flow through bone pores on Earth versus in micro-gravity. This suggests that interstitial fluid flow is influenced by the effects of micro-gravity leading to physiological changes in astronaut bones.

With the use deployable drones becoming more common research into their improvement is necessary. Deployable drones that are launched from tubes have size limits on the diameter of the propeller during launch and storage. The purpose of this research is to develop deployable propeller blades for practical uses, such as tube launched propeller driven drones and easier to transport wind turbine blades. A deployable propeller will allow for the utilization of larger propellers when a large non-deployable blade isn't an option. Because deployable propellers need to fold, the deployable propeller blades were designed to be hollow and with a slit across the leading and trailing edges of the blades. Because of this unique design, a deployable propeller is not as structurally sound as a conventional propeller, and it requires pressure distributions to be sure the propeller can withstand operation without becoming deformed and compromised. My work will focus on using Computational Fluid Dynamics (CFD) modeling and physical testing to test the aerodynamic design concerns of the deployable propeller, the effects of the unique design requirements on its aerodynamics, and developing a model to quantify the aerodynamic drivers of the deployable propeller. The results indicated that the modifications used to make the propeller deployable did not prevent the propeller from functioning properly and that the model was accurate enough to be used as a method for testing potential designs before manufacturing and physically testing prototypes.

This currently presented work is an evaluation of the characteristics of different cooling hole geometries to particulate ingestion clogging. Experimentation was conducted using a premixed bluff body flame combustor facility to generate high temperature combustor flow conditions. Sand ingestion along the cooling path of the combustion liner was reproduced using an air-assisted seeder providing consistent sand ingestion. Mass flow rate of cooling air was controlled using a sonic orifice downstream of a pressure regulator so that the mass flow rate of the air and sand mixture is independent of the clogging state. Pressure data upstream of a small section of a combustion liner was recorded to quantify the clogging of the different combustion liner cooling geometries over time. Several geometries were tested including 3 "S" shaped slots with varying width and length, along with tapered straight slots, and compared to the traditional straight round hole. It was found that a diverging orientation of the tapered slot had the most promising performance mitigating particulate deposition. The displacement boundary layer growth interaction with the main flow within the diverging section of the slot is discussed as the main contributing factor to resist clogging. The use of such a clogging-resistant combustion liner could drastically reduce the maintenance necessary for vehicles operating in sandy and dusty environments, reducing the overall operational cost, and lowering risks of complete failure of the aircraft propulsion system.

This multidisciplinary study provides a comprehensive visualization of airborne aerosols and droplets coming into contact with a crossflow of moving air utilizing both experimental particle measuring methods and multiphase computational fluids dynamics (CFD). The aim of this research is to provide a Eulerian visualization of how ventilation can alter the position and density of an aerosol cloud, with the goal of applying this information to our understanding of social distancing ranges within outdoor settings and ventilated rooms. The results indicate that even minor perpendicular crossflows across the trajectory of an aerosol cloud can greatly reduce both the linear displacement and density of the cloud, with negligible increases in density along the flow path.

Aerodynamic optimization is a key step in designing planes, cars, and even buildings. Numerical modeling is used to automate the optimization process and can use different methods to iterate through designs. In this process, consideration of the starting design is paramount as a poor choice can use up computational time and effort. Often, these designs are made with the intention of being out in the open, for which studies on shape variations in freestream situations abound. However, for the case where an object must be placed in the wake of another, there is little research. The study presented here aims to help fill this gap, starting with a case of an elliptical fairing design placed around a cylinder in the wake of a D shaped tube. The fairing itself is parameterized to gain an understanding of how its shape and relative location to the D-tube influence both the fairing itself and the D-tube. The evaluations are done using numerical models that are both validated and measured for uncertainty. Following that, the results are used to provide an initial fairing design for a real case, that being of an instrument on NASA's Dragonfly drone. The example is also used to provide a brief comparison to the trends seen in the 2D characterization as compared to trends seen in freestream design. In total, this research aims to provide a starting point for understanding how design choices affect the aerodynamics of a fairing in a bluff body wake.

The research presented here provides a basis for understanding the hydrodynamics of surfboard fin geometries. While there have been select studies on fins there has been little correlation to the shape of the fin and its corresponding hydrodynamic performance. This research analyzes how changing the planform shape of a surfboard fin effects its performance and flow field. This was done by isolating the taper and sweep distribution of a baseline geometry and varying each parameter individually whilst maintaining a constant span and surface area. The baseline surfboard fin was used as a template in Matlab to generate a set of x and y coordinates that defined the outline of the fin shape. These coordinates were then altered by changing either the sweep or taper distribution and resulted in new, unique planform shapes. The new shapes were used to generate 3D models with the NACA 0006 foil as the cross-section hydrofoil. After the geometry was modeled, each fin was meshed and simulated in CFD for incidence angles ranging from 0o to 20o and a fin Reynolds Number of 3.51x105. When the sweep distribution was changed, there was a direct correlation to vortex formation off the leading edge. Increasing the sweep generated a stronger vortex that persisted for higher angles of attack and resulted in higher moments but increased drag. Changing the taper distribution was not as influential. The tapered fin set showed similar flow fields and body forces to each other. Making a fin more rectangular had slight decreases in drag but made the shape more prone to separation.

This thesis presents changes to the design of the Prototype Vehicles Laboratory (PROVE Lab) Endurance Car, an electric car intended to break the Guinness World Record for the single-charge range of an electric vehicle. The design range is 1609.34 km, however at the design velocity of 104.6 kph, the drag is 196 N; which requires more battery capacity than the 100 kWh maximum of the baseline model. With a fixed frontal area, drag reduction can come from lowered velocity or reduced CD. CD reduction is attempted in four ways: side skirts between the fenders, a raised ride height, an elongated diffuser, and a widened rear. Side skirts were added to move pressure recovery from the front ducts to the diffuser by lowering the pressure between the side skirts; this had the intended effect but increased the tendency of the flow to separation in the already-separated areas. There was no significant change in pressure drag, but the shear drag and downforce increased. The ride height was increased to reduce drag and downforce; this change did not have a significant effect on the resultant forces and the separation on the underbody was largely unchanged. The diffuser was extended by 12.7 cm without modifying the aspect ratio, to lower the divergence angle. The pressure and shear drag reduced by 8 N and 1.1 N, respectively, and downforce decreased by 80 N, but separation in the diffuser was not eliminated. Finally, the fourth strategy reduced the divergence angle to approximately zero degrees by widening the center of the vehicle. This decreased pressure drag by 13 N and downforce by 188 N. Additionally, this strategy allows a larger 180 kWh battery, which permits 1609.34 km of range at 104.6 kph.