An accurate measurement of total temperature in turbomachinery flows remains critical for component life models and cycle performance optimization. While many techniques exist to measure these flows, immersed thermocouple based probes remain highly desirable due to well established practices for probe design and implementation in typical industrial flow applications. However, as engine manufacturers continue to push towards higher maximum cycle temperatures and smaller flow passages, the continued use of these probes requires new probe designs considering both improved sensor durability and measurement accuracy. Increased maximum temperatures introduce many challenges for total temperature measurements using conventional immersed probes, including increased influences of conduction, convection, and radiation heat transfer between the sensor, fluid and the surroundings due to large thermal gradients present in real turbomachinery systems. While these effects have been previously investigated, the available design models are very limited to specific geometries and flow conditions. In this Dissertation, a more fundamental understanding of the flow behavior around typical vented shield style total temperature probes as a function of probe geometry and operating condition is gained using results from high-fidelity Computational Fluid Dynamics simulations with Conjugate Heat Transfer. A parametric study was conducted considering three non-dimensional probe geometric ratios (vent location to shield length (0.029-0.806), sensor diameter to shield inner diameter (0.252-0.672), and shield outer diameter to strut/mount thickness (0.245-0.759)) and three operating conditions (total temperature (70, 850, 2500°F) and pressure (1, 1, 10 atm), respectively) at a moderate Mach number of 0.4. Results were further quantified in the form of new empirical correlations necessary for rapid thermal performance evaluations of current and future probe designs. Additionally, a new mixed-fidelity or Reduced Order Modeling technique was developed which allows the coupling of high fidelity surface heat transfer data from CFD with a generalized form of the 1-D conducting solid equations for evaluating radiation and transient influences on sensor performance. These new flow and heat transfer correlations together with the new Reduced Order Modeling technique developed here greatly enhance the capabilities of designers to evaluate performance of current and future probe designs, with higher accuracy and with significant reductions in computational resources. / Doctor of Philosophy / An accurate measurement of total temperature in turbomachinery flows remains critical for component life models and cycle performance optimization. While many techniques exist to measure these flows, immersed thermocouple based probes remain highly desirable due to well established practices for probe design and implementation in typical industrial flow applications. However, as engine manufacturers continue to push towards higher maximum cycle temperatures and smaller flow passages, the continued use of these probes requires new probe designs considering both improved sensor durability and measurement accuracy. Increased maximum temperatures introduce many challenges for total temperature measurements using conventional immersed probes, including increased influences of conduction, convection, and radiation heat transfer between the sensor, fluid and the surroundings due to large thermal gradients present in real turbomachinery systems. While these effects have been thoroughly described and quantified in the past, the available design models are very limited to specific geometries and flow conditions. In this Dissertation, a more fundamental understanding of the flow behavior around typical vented shield style total temperature probes as a function of probe geometry and operating condition is gained using results from high-fidelity Computational Fluid Dynamics simulations with Conjugate Heat Transfer (CHT) capabilities. Results were further quantified in the form of new empirical correlations necessary for rapid thermal performance evaluations of current and future probe designs. Additionally, a new mixed-fidelity or Reduced Order Modeling (ROM) technique was developed which allows the coupling of high fidelity surface heat transfer data from CFD with a generalized form of the 1-D conducting solid equations for readily predicting the impact of radiation environment and transient errors on sensor performance.

Bone Cancer Research Trust / The full text will be available at the end of the embargo: 6th October 2027

The present thesis focuses on evaluating a conjugate heat transfer (CHT) simulation in a ribbed cooling passage with a fully developed flow assumption using LES with the immersed boundary method (IBM-LES-CHT). The IBM with the LES model (IBM-LES) and the IBM with CHT boundary condition (IBM-CHT) frameworks are validated prior to the main simulations by simulating purely convective heat transfer (iso-flux) in the ribbed duct, and a developing laminar boundary layer flow over a two-dimensional flat plate with heat conduction, respectively. For the main conjugate simulations, a ribbed duct geometry with a blockage ratio of 0.3 is simulated at a bulk Reynolds number of 10,000 with a conjugate boundary condition applied to the rib surface. The nominal Biot number is kept at 1, which is similar to the comparative experiment. As a means to overcome a large time scale disparity between the fluid and the solid regions, the use of a high artificial solid thermal diffusivity is compared to the physical diffusivity. It is shown that while the diffusivity impacts the instantaneous fluctuations in temperature, heat transfer and Nusselt numbers, it has an insignificantly small effect on the mean Nusselt number. The comparison between the IBM-LES-CHT and iso-flux simulations shows that the iso-flux case predicts higher local Nusselt numbers at the back face of the rib. Furthermore, the local Nusselt number augmentation ratio (EF) predicted by IBM-LES-CHT is compared to the body fitted grid (BFG) simulation, experiment and another LES conjugate simulation. Even though there is a mismatch between IBM-LES-CHT prediction and other studies at the front face of the rib, the area-averaged EF compares reasonably well in other regions between IBM-LES-CHT prediction and the comparative studies. / Master of Science / The present thesis focuses on the computational study of the conjugate heat transfer (CHT) investigation on the turbine internal ribbed cooling channel. Plenty of prior research on turbine internal cooling channel have been conducted by considering only the convective heat transfer at the wall, which assumes an iso-flux (constant heat flux) boundary condition at the surface. However, applying an iso-flux condition on the surface is far from the realistic heat transfer mechanism occurring in internal cooling systems. In this work, a conjugate heat transfer analysis of the cooling channel, which considers both the conduction within the solid wall and the convection at the ribbed inner wall surface, is conducted for more realistic heat transfer coefficient prediction at the inner ribbed wall. For the simulation, the computational mesh is generated by the immersed boundary method (IBM), which can ease the mesh generation by simply immersing the CAD geometry into the background volume grid. The IBM is combined with the conjugate boundary condition to simulate the internal ribbed cooling channel. The conjugate simulation is compared with the experimental data and another computational study for the validation. Even though there are some discrepancy between the IBM simulation and other comparative studies, overall results are in good agreement. From the thermal prediction comparison between the iso-flux case and the conjugate case v using the IBM, it is found that the heat transfer predicted by the conjugate case is different from the iso-flux case by more than 40 percent at the rib back face. The present study shows the potential of the IBM framework with the conjugate boundary condition for more complicated geometry, such as full turbine blade model with external and internal cooling system.

Jump-diffusion models can under certain assumptions be expressed as partial integro-differential equations (PIDE). Such a PIDE typically involves a convection term and a nonlocal integral like for the here considered models of Merton and Kou. We transform the PIDE to eliminate the convection term, discretize it implicitly using finite differences and the second order backward difference formula (BDF2) on a uniform grid. The arising dense linear system is solved by an iterative method, either a splitting technique or a circulant preconditioned conjugate gradient method. Exploiting the Fast Fourier Transform (FFT) yields the solution in only $O(n\log n)$ operations and just some vectors need to be stored. Second order accuracy is obtained on the whole computational domain for Merton's model whereas for Kou's model first order is obtained on the whole computational domain and second order locally around the strike price. The solution for the PIDE with convection term can oscillate in a neighborhood of the strike price depending on the choice of parameters, whereas the solution obtained from the transformed problem is stabilized. / Master of Science

Hyperthermia is a cancer treatment modality that raises cancerous tissue to cytotoxic temperature levels for roughly 30 to 45 minutes. Hyperthermia treatment planning refers to the use of computational models to optimize the heating protocol to be used in a hyperthermia treatment. This thesis presents a method to optimize a hyperthermia treatment heating protocol. An algorithm is developed which recovers a heating protocol that will cause a desired amount of thermal damage within a region of tissue. The optimization algorithm is validated experimentally on an albumen tissue phantom. The transient temperature distribution within the region is simulated using a two-dimensional, finite-difference model of the Pennes bioheat equation. The relationship between temperature and time is integrated to produce a damage field according to two different models; Henriques'' model and the thermal dose model (Moritz and Henriques (1947)), (Sapareto and Dewey (1984)). A minimization algorithm is developed which re duces the value of an objective function based on the squared difference between an optimal and calculated damage field. Either damage model can be used in the minimization algorithm. The adjoint problem in conjunction with the conjugate gradient method is used to minimize the objective function of the control problem. The flexibility of the minimization algorithm is proven experimentally and through a variety of simulations. With regards to the validation experiment, the optimal and recovered regions of permanent thermal damage are in good agreement for each test performed. A sensitivity analysis of the finite difference and damage models shows that the experimentally-obtained extent of damage is consistently within a tolerable error range. Excellent agreement between the optimal and recovered damage fields is also found in simulations of hyperthermia treatments on perfused tissue. A simplified and complex model of the human skin were created for use within the algorithm. Minimizations using both the Henriques'' model and the thermal dose model in the objective function are performed. The Henriques'' damage model was found to be more desirable for use in the minimization algorithm than the thermal dose model because it is less computationally intensive and includes a mechanism to predict the threshold of permanent thermal damage. The performance of the minimization algorithm was not hindered by adding complexity to the skin model. The method presented here for optimizing hyperthermia treatments is shown to be robust and merits further investigation using more complicated patient models. / Master of Science

The U.S. Evolutionary Power Reactor (EPR) is a new, large-scale pressurized water reactor made by AREVA NP Inc. Surrounding the core of this reactor is a steel wall structure sitting inside called the heavy reflector. The purpose of the heavy reflector is to reduce the neutron flux escaping the core and thus increase the efficiency of the reactor while reducing the damage to the structures surrounding the core as well. The heavy reflector is heated due to absorption of the gamma radiation, and this heat is removed by the water flowing through 832 cooling channels drilled through the heavy reflector. In this project, the temperature distribution in the heavy reflector was investigated to ascertain that the maximum temperature does not exceed the allowable temperature of 350 C, with the intent of modifying the flow distribution in the cooling channels to alleviate any hot spots. The analysis was conducted in two steps. First, the flow distribution in the cooling channels was calculated to test for any maldistribution. The temperature distribution in the heavy reflector was then calculated by simulating the conjugate heat transfer with this flow distribution as the coolant input. The turbulent nature of the flow through the cooling channels made the calculation of the flow distribution computationally expensive. In order to resolve this problem, a simplification method using the "equivalent flow resistance" was developed. The method was validated by conducting a few case studies. Using the simplified model, the flow distribution was calculated and was found to be fairly uniform. The conjugate heat transfer calculation was conducted. The same simplification method used in the flow distribution analysis could not be applied to this calculation; therefore, the computational cost of this model was reduced by lowering the grid density in the fluid region. The results showed that the maximum temperature in the heavy reflector is 347.7 C, which is below the maximum allowable temperature of 350 C. Additional studies were conducted to test the sensitivity of the maximum temperature with change in the flow distribution in the cooling channels. Through multiple calculations, the maximum temperature did not drop more than 3 C; therefore, it was concluded that the flow distribution in the cooling channels does not have significant effect on the maximum temperature in the heavy reflector. / Master of Science

yes / To achieve a better solution of disc brake heat transfer problem under heavy duty applications, the accurate prediction of transient field of heat transfer coefficient is significant. Therefore, an appropriate coupling mechanism between flow field and temperature field is important to be considered. In this paper, a transient conjugate heat transfer co-simulation disc brake model has been presented in order to improve the accuracy and feasibility of conventional coupled FE and CFD method. To illustrate the possible utilizations of this co-simulation method, a parameter study has been performed e.g. geometric, material, and braking application. The results show the advantage of the co-simulation method in terms of computing time efficiency and accuracy for solving complex braking heat transfer problem.

[EN] The present PhD thesis aims at the development of a one-dimensional solver capable of solving single- and two-phase flow fluid systems. The novelty of this project lies in the use of an open source CFD platform, called OpenFOAM, as a development framework for the new tool. For the new solver development, the conservation equations based on Navier- Stokes (three-dimensional system) have been analyzed and reduced to one dimension. For the two-phase simulations, the Two Fluid Model method was used as base. In addition, a series of empirical models have been selected as closing equations of the system. The final solver includes a series of requirements that reinforce their capabilities. Among them, the use of a second mesh that represents the solid and takes into account the heat transmitted to the fluid by conduction through a solid, stands out. On the other hand, the possible transfer of mass between phases in twophase fluids has been taken into account. Similarly, a subcooled boiling model has been implemented which takes into account the possible generation of vapor near the wall while the bulk is kept below saturation temperature. Finally, this paper presents the verification and validation of the solver. The verification has been carried out mainly with the system code TRACE, whose validation has been demonstrated in numerous works and its use is very extended in the scientific community. For the validation, we have the results of two experimental cases that allow us to demonstrate the physical validity of the new application developed. The use of this platform allows for a much more direct coupling between one- and three-dimensional domains, obtaining a better optimization of the calculation. / [ES] El presente trabajo de doctorado tiene por objetivo el desarrollo de un solver unidimensional capaz de resolver sistemas de fluidos monofásicos y bifásicos. La novedad de este proyecto reside en el uso de una plataforma CFD de código abierto, llamada OpenFOAM, como marco para el desarrollo de la nueva herramienta. Para el desarrollo del nuevo solver, se han analizado las ecuaciones de conservación basadas en Navier-Stokes (tridimensionales) y se han reducido a una dimensión. Para la parte bifásica del solver, se utiliza el método Two Fluid Model. Además, se han incluido todos los modelos empíricos necesarios como ecuaciones de cierre del sistema. El solver final incluye una serie de requerimientos que refuerzan sus capacidades. Entre ellas, destacan, por un lado, el uso de una segunda malla que represente el sólido y tenga en cuenta el calor transmitido al fluido por conducción a través de un sólido. Por otro lado, se ha tenido en cuenta la posible transferencia de masa entre fases en fluidos bifásicos. Igualmente, se ha implementado un modelo de ebullición subenfriada que tiene en cuenta la posible generación de vapor cerca de la pared mientras el centro del fluido se mantiene por debajo de la temperatura de saturación. Finalmente, este trabajo presenta la verificación y validación del solver. La verificación se ha realizado principalmente con el código de sistema TRACE. Para la validación, se cuenta con los resultados de dos casos experimentales que permiten demostrar la validez física de la nueva aplicación desarrollada. La implementación del nuevo solver en esta plataforma abierta permite un futuro acoplamiento mucho más directo entre mallas unidimensionales y tridimensionales, obteniendo una mayor optimización del cálculo. / [CA] El present treball de doctorat té per objectiu el desenvolupament d'un nou solver unidimensional capaç de solucionar sistemes amb fluids monofàsics i bifàsics. La novetat d'aquest projecte resideix en l'ús d'una plataforma CFD de codi obert, anomenada OpenFOAM com a marc de desenvolupament de la nova eina. Per al desenvolupament del nou solver, s'han analitzat les equacions de conservació basades en Navier-Stokes (tridimensionals) i s'han reduït a una dimensió. Per a la part bifàsica del solver s'utilitza el mètode Two Fluid Model. A més, s'han inclòs tots els models empírics necessaris com a equacions de tancament del sistema. El solver final inclou una sèrie de requeriments que reforcen les seues capacitats. Entre elles, destaquen, d'una banda, l'ús d'una segona malla que represente el sòlid i es tinga en compte la calor transmesa al fluid per conducció a través d'un sòlid. D'altra banda, s'ha tingut en compte la possible transferència de massa entre fases en fluids bifàsics. Igualment, s'ha implementat un model d'ebullició subrefredada que té en compte la possible generació de vapor prop de la paret mentre el centre del fluid es manté per davall de la temperatura de saturació. Finalment, aquest treball presenta la verificació i validació del solver. La verificació s'ha realitzat principalment amb el codi de sistema TRACE, la validació del qual s'ha demostrat en nombrosos treballs i el seu ús està molt estés en la comunitat científica. Per a la validació, es compta amb els resultats de dos casos experimentals que permeten demostrar la validesa física de la nova aplicació desenvolupada. L'ús d'esta plataforma permiteix un futur acoblament més directe, entre elements unidimensionals i tridimensionals, obtenint una major optimització del càlcul. / Gómez-Zarzuela Quel, C. (2020). Development and assessment of a one-dimensional CFD solver for boiling flows in bubbly regimes [Tesis doctoral]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/148368

No / Development of therapeutic strategies for tumor-selective delivery of therapeutics through exploitation of the proteolytic tumor phenotype has significant scope for improvement of cancer treatment. ICT2588 is a peptide-conjugated prodrug of the vascular disrupting agent (VDA) azademethylcolchicine developed to be selectively hydrolyzed by matrix metalloproteinase-14 (MMP-14) within the tumor. In this report, we extend our previous proof-of-concept studies and demonstrate the therapeutic potential of this agent against models of human colorectal, lung, breast, and prostate cancer. In all tumor types, ICT2588 was superior to azademethylcolchicine and was greater or comparable to standard clinically used agents for the respective tumor type. Prodrug activation in clinical human lung tumor homogenates relative to stability in human plasma and liver was observed, supporting clinical translation potential. A major limiting factor to the clinical value of VDAs is their inherent cardiovascular toxicity. No increase in plasma von Willebrand factor (vWF) levels, an indicator of systemic vascular dysfunction and acute cardiovascular toxicity, was detected with ICT2588, thereby supporting the tumor-selective activation and reduced potential of ICT2588 to cause cardiovascular toxicity. Our findings reinforce the improved therapeutic index and tumorselective approach offered by ICT2588 and this nanotherapeutic approach.

We investigated the structure and defects associated with interphase boundaries between a γ (fcc) matrix and plate-shaped precipitates of the δ (orthorhombic) phase in Inconel 718. Based upon transmission electron microscopy (TEM) observations, the average habit plane was confirmed to be (111)_γ which is consistent with previous reports. A parallel array of misfit dislocations with Burgers vector b=1/6[112̅]_γ, (designated M1) are always observed lying along the [11̅0] direction. Another array of misfit dislocations appears in some regions of the interface with Burgers vector b=1/6[21̅1̅]_γ (designated M2). These dislocations also lie along the [11̅0] direction. Irregular ledges were identified on the interface and are believed to contribute to the thickening of δ plates. Dislocations in the matrix were also characterized. Most matrix dislocations have a 1/2[1̅01]_γ Burgers vector. The growth ledges in the habit plane of a single δ plate have a variety of effective Burgers vectors. A geometric matching approach based upon near-coincident sites was employed to explain the interfaces structure of interphase boundaries in Inconel 718, as well as fdc/bcc in Ni-45wt% Cr. In both cases, the conjugate plane is the plane with the highest areal density of near-coincident sites over a small region while the average habit plane is determined by the continuity of near-coincidence sites over a large area. The M1 interfacial dislocations in the γ/δ interface accommodate misfit in the habit plane whereas M2 dislocations do not and are probably a by-product of the dissociation of matrix dislocations. In the fcc/bcc system, the habit plane is not parallel to the conjugate plane and the partial dislocations associated with matrix stacking faults improve matching in the habit plane even though their Burgers vector lies out of this plane. / Ph. D.