A framework for performing mesh morphing in a conjugate simulation in the commercial Computational Fluid Dynamics (CFD) software ANSYS Fluent is presented and validated. A procedure for morphing both the fluid and solid domains to simulate the protrusion of deposit into the fluid while concurrently altering and adding to the solid regions is detailed. The ability to delineate between the original metal sections of the solid and the morphed regions which represent deposit characteristics is demonstrated. The validity and predictive capability of the process is tested through simulation of a canonical impingement jet. A single over-sized impingement jet (6.35 mm) at 894 K and an average flow velocity of 56.5 m/s is used to heat a nickel-alloy target plate. One gram of 0-5 μm Arizona Road Dust (ARD) is delivered to the target and a Particle Shadow Velocimetry (PSV) technique is used to capture the transient growth of the deposit structure on the target. Thermal infrared images are taken on the backside of the target and synchronized with the PSV images. The experiment is modeled computationally using the Fluent Discrete Phase Model (DPM) and the Ohio State University (OSU) Deposition Model for sticking prediction. The target is morphed according to the particulate volume prediction. The deposit regions are assigned an effective conductivity (keff) representative of porous deposit, and the fluid and thermal computations are reconverged. 10 mesh morphing iterations are performed accounting for the first half of the experiment. The morphed deposit volume and height are compared to the experiment and show reasonable agreement. The backside target temperatures are also compared, and the simulations show the ability to predict the reduction in temperature that occurs as the growing deposit insulates the metal surface. It is demonstrated that the assignment of unique thermal conductivities to the deposit and metal cells within the solid is critical. With a more robust and accurate implementation of the deposit keff, this conjugate mesh morphing framework shows potential as a tool for predicting the thermal impact of deposition.

A computational analysis is performed to determine if particulate impact events on the external surfaces of gas turbine engine rotor blades can be faithfully replicated in an experimental rotor cascade. The general electric (GE) energy efficient engine (E3) first-stage turbine flow-field at cruise conditions is first solved using a steady-state explicit mixing plane (MP) approach. To model flow in the cascade, a single E3 rotor periodic domain is then constructed with an inlet section matching the relative flow incidence angle from the mixing plane calculation. The mass-averaged relative flow conditions at the inlet and outlet of the mixing plane rotor section are imposed on the cascade boundaries and a steady solution is found. Particles with diameters ranging from 1 to 25 µm are tracked through each domain and the OSU deposition model is implemented to dictate the sticking and rebounding action of particles impacting solid surfaces. It is discovered that both the locations and parameters of the impacts in the cascade vary significantly from the engine environment. For smaller particles, this is credited to a stronger upstream influence of the blade on the cascade flow-field. As size increases, differences in deposition are instead driven by the interaction of the full-stage vane with the particles. The lack of a vane in the cascade causes drastically different particle inlet vectors over the rotor than are seen in the engine setting. The radial differences of particle impact locations are explored, and the role that pressure plays is considered.

The effect of absolute pressure on deposition is studied in the High-Pressure Deposition Facility at The Ohio State University. Mass flow blockage trends are presented for the case of deposition in a single-wall flat plate effusion cooling geometry. Arizona Road Dust in the ranges of 0–10 μm and 0–3.5 μm is delivered to a 950 K coolant flow at a pressure ratio of 1.03 at absolute pressures ranging from 1 to 15.77 atm. The primary results indicate a non-linear decrease in blockage with increasing absolute pressure. Additional targeted experimental and companion computational fluid dynamics simulations are used to elucidate the relative importance of 3 physical mechanisms responsible for the trend with pressure: (1) the increase in effusion hole discharge coefficient (2) altered particle trajectories due to reduced effective Stokes and (3) altered erosion due to reduced effective Stokes. Results reveal that blockage and sticking rates are minimally affected by the changing velocity field due to the increase in discharge coefficient, thus the increased particle drag effect on particle trajectories and erosion due to changing flow density is the primary candidate. To support these conclusions, mesh morphing simulations of a 0–10 μm test are performed at 1 and 15.77 atm using the OSU Deposition Model, which captures both impact velocity and angle dependencies of deposition. The resulting structures and their unique characteristics are compared to experimental deposits, and the computational and experimental blockage histories support the conclusion that increased drag is the primary mechanism.

The role of temperature on deposition in gas turbine internal cooling geometries is investigated. Single impingement cones are developed by an oversized (6 mm) impinging jet over a range of temperatures and flow velocities using 0–5 μm ARD. Cone size was found to increase with increasing temperature and decrease with increasing velocity. Capture efficiency and cone angle effects are presented, and packing factor data is used as a metric to determine if the contact area (Acont) for adhesion explains the trends seen with temperature. It is systematically demonstrated that the surface free energy (γ) is likely a first order function of temperature in internal deposition for the range of temperatures investigated. Candidate physical mechanisms that may cause increased adhesive force at elevated temperatures are identified. Temperature dependent adhesion is added to the OSU Deposition Model which is then used with a simplified morphing approach to match temperature induced blockage patterns in a vane leading edge cooling experiment. This process is improved upon using a full mesh morphing routine and matching two of the experimental deposition cones at varied flow temperatures. The added fidelity that mesh morphing affords is demonstrated.