The purpose of this research is to reduce the amount of waste generated in Department of Energy nuclear cleanup efforts currently underway. Due to the highly radioactive nature of the waste, any fluid that contacts the waste must then be treated and processed as waste. To minimize the fluids contaminated during flushing, this research aims to provide a basis for the flushing of High Level Waste (HLW) pipelines. Edgar Plastic Kaolin (EPK) with solid particles of a nominal diameter of 1 micron was used as a simulacrum for HLW. An Eulerian-Eulerian simulation built in StarCCM+ software, with a k-ω turbulence model, and a drag coefficient to connect the solid EPK phase with the liquid phase, was used to simulate the flushing of pipelines. Velocities from 3 ft/s to 10 ft/s were investigated to find the highest volumetric efficiency, and it was determined that 10 ft/s was the optimal flushing velocity.

Supersonic channel airfoil design techniques have been shown to significantly reduce drag in high-speed flows over diamond shaped airfoils by Ruffin and colleagues. The effect of applying these techniques to a NACA 66-206 airfoil is presented. The design domain entails channel heights of 8-16.6% thickness-to-chord and speeds from Mach 1.5-3.0. Numerical simulations show an increase in the lift-to-drag ratio for airfoils at Mach 2.5 at a 35,000-ft altitude with a 12% channel height geometry showing a benefit of 17.2% at 6-deg angle of attack and a sharp channel leading edge. Wave drag is significantly reduced while viscous forces are slightly increased because of greater wetted area. Lift forces compared to clean airfoil solutions were also decreased, due mainly to the reduction in the length of the lifting surfaces. A tensile yield failure structural analysis of a typical beam found an 11.4% channel height could be implemented over 50% of the span between two typical ribs. A three dimensional wing was designed with the determined slot geometry and two dimensional flow analyses. An overall increase in L/D of 9% was realized at Mach 2.5 at a 35,000-ft altitude and 6-deg angle of attack.

This paper seeks to explore the effects of an active drag control method known as distributed forcing on a 3D bluff body with a blunt base. The 9.5 x 15.25 x 3 inch aluminum model constructed for this experiment has an elliptically shaped nose and rectangular aft section. The model is fitted with four, 12 Volt fans, forcing the freestream air into and out of 1 mm thick slots on the upper and lower trailing edges. The forcing is steady in time, held at a constant forcing velocity though all Reynolds numbers, but varies roughly sinusoidally in the spanwise direction across the model. Testing was conducted at Reynolds numbers of 50,000, 100,000 and 150,000 at California Polytechnic State University, San Luis Obispo in the Aerospace Engineering Department’s subsonic 3’ by 4’ wind tunnel. Effectiveness of the distributed forcing method was evaluated by measuring the base pressure on the model using a Scanivalve system. By measuring multiple static pressure ports, it was found that base pressure increased by 15.3% and 4.2% at Reynolds numbers of 50,000 and 100,000 respectively, and showed a decrease of 2.7% at a Reynolds number of 150,000. Total drag on the model was also measured using a sting balance mount fitted with strain gauges. This test showed a drag reduction of 15.8% and 5.5% for Reynolds numbers of 50,000 and 100,000 respectively, and an increase in drag of 2.0% at Reynolds number of 150,000, when omitting external power required to run the forcing assembly. The forcing assembly was shown to require nearly 12 times the power to operate than it saves in drag reduction at Reynolds number of 50,000. In addition, a thermal anemometry measurement of streamwise velocity of the near wake behind the bluff body was conducted to qualitatively assess the attenuation of the vortex street behind the model. Distributed forcing shows that as the freestream velocity is increased as compared to the forcing velocity, the change in energy spectral density is lessened, and as such, the largest attenuation in vortex shedding is at Reynolds number of 50,000 while nearly no change is seen at the Reynolds number of 150,000.

The Goldschmied Propulsor concept combines boundary layer suction and boundary layer ingestion to improve propulsive efficiency and reduce drag on an axisymmetric body. This investigation of a Goldschmied Propulsor aimed to determine influential characteristics of the suction slot geometry to aid in better slot geometry design and to decrease the suction flow requirements for maintaining attached flow over the entire model surface. The Propulsor model was 38.5 inches in length with a max diameter of 13.5 inches. Three suction slot geometries were investigated with the addition of aluminum cusps to the slot entrance. The cusps varied in the distance they protruded into the incoming suction flow and in the angle they took from the lip into the suction slot. Wind tunnel testing was completed in the Cal Poly 3ft x 4ft test section of the draw-down tunnel at a Reynolds Number of 2.3x106. Results show that of the three cusp geometries, the smallest Cusp A protruding only 0.05 inches into the suction flow, produced the greatest reductions in pressure drag and total axial force for the fan speeds tested. When compared to the no cusp condition, none of the three cusp geometries produced any significant improvement in total drag or in required suction flow rate.

This research paper aims to investigate the optimization of smaller propeller blades to achieve maximum efficiency by studying the effect of the twist angle on reducing drag, increasing thrust, and preventing rapid wear on the blade. Inefficient propellers consume a significant amount of energy, particularly during low-speed flights. The low Reynolds number regime challenges aviation engineers to design propellers with the highest possible efficiency to minimize energy losses. The primary objective of this thesis is to optimize smaller propeller blade shapes to enable them to produce maximum efficiency. The advanced ratio of a propeller blade heavily influences the blade's performance efficiency. The analysis uses the modified Blade Element Momentum Theory (BEM) and the Betz optimization method, with an analytical approach for comparing methods. The results show that the aerodynamic twist angle plays a vital role in propeller blade performance in a low Reynolds number regime. An optimized twist angle can improve efficiency up to eight times, as per the preliminary data, highlighting the critical role of optimization in achieving maximum efficiency in propeller blades.

This work aims to identify the key flow parameters that influence flame acceleration in a semi-confined square channel. A transverse fluidic jet was used as an active flow blockage mechanism and to introduce turbulence into the propagating flame. Three experimental parameters were used to examine the relative influence of (1) mixture reactivity defined here as system equivalence ratio (SER), (2) jet mixture composition (JMC), and the momentum ratio (MR) on the acceleration of laminar premixed methane flame. High-speed PIV and schlieren photography were utilized to characterize the instantaneous flow-field conditions throughout the flame-jet interaction. Using these diagnostic techniques, flame front positions and local velocity vector fields have been spatially and temporally resolved. Changes in flame properties including flame structure, velocity, and vorticity were tracked as a function of time. Stoichiometric equivalence ratios were more effective in the production of vorticity and the promotion of flame acceleration. The stoichiometric condition accelerated the flame to the highest final flame velocity of the three parameters examined. Different compositions of the jet mixture demonstrated that the flame acceleration is primarily affected by the jet turbulence and not on the reactivity of the jet compositions. Out of the three parameters examined, the momentum ratio parameter had the least amount of influence on the flow field and flame acceleration. The increase of 33 % in the momentum ratio had negligible effect in the final flame front velocity and implies that the jet turbulence is the main driving mechanism for flame acceleration.

As industry transitions to a net-zero carbon future, turbulent premixed combustion will remain an integral process for power generating gas turbines and are also desired for aviation engines due to their ability to minimize pollutant emissions. However, accurately predicting the behavior of a turbulent reacting flow field remains a challenge. To better understand the dynamics of premixed reacting flows, this study experimentally investigates the evolution of turbulence in a high-speed bluff-body combustor. The combustor is operated across a range of equivalence ratios from 0.7-1 to quantify the role of heat release and flame scales on the evolution of turbulence as the flow evolves from reactants to products. High-speed particle image velocimetry and CH* chemiluminescence imaging systems are simultaneously employed to quantify turbulent flame and flow dynamics. The results demonstrate that the flame augments turbulence fluctuations as the flow evolves from reactants to products for all cases. However, turbulence fluctuations increase monotonically with the heat of combustion and corresponding turbulent flame speed. Nondimensional spatial profiles of turbulence are used to develop a correlation to predict the increase in turbulent fluctuations in an extended progress variable space. A Reynolds Averaged Navier Stokes (RANS) decomposition is also explored to better characterize the effects of heat release on turbulence evolution dynamics. The correlations and RANS decomposition can guide modeling capabilities to better predict confined turbulent reacting flows and accelerate design strategies for premixed turbines with carbon-free fuels.

The Rotating Detonation Combustor (RDC) has, in recent years, been a subject of great interest in the pressure-gain combustion research community. Researchers have been investigating the RDC as a potential improvement over current combustors in today's turbomachinery-based power generation systems. With the theoretical efficiency boost that detonations provide over deflagrating combustors, RDCs have the promise to be a next step in fuel/cost savings in the power generation industry. One mode of research to push an RDCs capabilities is the potential use of combustible carbon/hydrocarbon solid particles in addition to liquid or gaseous fuels. These particles are a source of high energy density and, once added, can reduce the amount of liquid/gaseous fuel needed while operating at the same fuel-to-air ratio. These organic particles are derived from grown sources making them cost-effective and sustainable, in contrast to mined or drilled fossil fuels. Carbon black, peanut flour, and powdered sugar were seeded into a 6-inch diameter RDC operating on a gaseous hydrogen-air mixture. This was done at the leanest hydrogen-air ratio possible where the combustor, operating on just gaseous fuel, would still experience stable detonation waves. Solid fuel was then seeded in place of the gaseous fuel at varying ratios to study its effects on the ability of the combustor to continue to experience detonations. In general, while stable detonations were achieved when solid fuel began replacing the gaseous fuel, the greater the concentration of solid particles compared to gaseous fuel, the greater the likelihood of irregular detonation modes. These modes were observed using a high-speed camera: taking back-end imaging observations to measure characteristics of present detonation waves, including wave number, speed, stability, and phase angle. CTAPs were also added along the length of the outer body of the RDC to take pressure measurements during operation.

Temperature measurements can be difficult to obtain across many different harsh environments such as engine combustion chambers, engine exhaust temperatures, and explosion fireballs. While there are alternate methods to measure fluid temperature such as laser measurements, acoustic measurements, and camera imaging techniques, these methods can often be expensive, difficult to implement, and not able to see within the environment. Thermocouples are popular sensors because they are cheap and easy to implement across a wide range of applications and can measure temperature in areas where other methods cannot reach or see. However, while these sensors are very popular and versatile, they do have some disadvantages, mainly, the response time. When the testing environment becomes harsh, the thermocouple size increases so that the sensor can survive. Unfortunately, when the thermocouple size increases, so does the time that it takes to sense the gas temperature. For this research, the environment will mimic an explosive environment with very fast temperature rise times that will require quick sensor response. This will not be achievable with a single thermocouple; so, multiple thermocouples will be used. This research focuses on evaluating past multi-thermocouple reconstruction techniques to determine which available method is the most accurate and feasible to implement. Of the methods researched, this work has found that a frequency domain method proposed by Forney and Fralick provides temperature estimates as accurate as 0.5% off the average steady state temperature with an average percent error of 5%.

Fluids-related issues in the Aerospace industry are often multiphase in scope. Numerical modeling, such as computational fluid dynamics, is used to describe these problems, as they are difficult or impossible to describe analytically. This research uses computational fluid dynamics to describe multiphase problems related to melting-solidification and particle impingement. Firstly, a numerical model was established that uses the Volume-of-Fluid method to resolve a melting/solidifying particle. This model was verified against experiments and simplified analytical models, and a mesh independence study was done to ensure the results were independent of the mesh sizing. Next, the model was applied to two separate but related problems. The Artemis program has renewed interest in lunar dust mitigation. It is proposed that lunar regolith partially melts and becomes "sticky" when coming into contact with a jet flame, like a landing rocket. The method above was applied to a lunar regolith particle to show how these "sticky" particles can adhere to surfaces. The direct resolution methodology was also applied to a melted sand particle impinging and infiltrating a yttria-stabilized zirconia thermal barrier coating, as seen in engine turbines. Sand can infiltrate the thermal barrier coating and decrease its effectiveness. The infiltration from a single particle was compared to the infiltration from a stream of melted sand. These three efforts showcase the usefulness of directly resolving small particles using the Volume-of-Fluid method.