Computational fluid dynamic and thermal stress analysis of coatings for high‐temperature corrosion protection of aerospace gas turbine blades

Abstract

The current investigation presents detailed finite‐element simulations of coating stress analysis for a three‐dimensional, three‐layered model of a test sample representing a typical gas turbine component. Structural steel, titanium alloy, and silicon carbide are selected for main inner, middle, and outermost layers respectively. ANSYS is used to conduct three types of analysis—static structural, thermal stress analysis, and also computational fluid dynamic erosion (via ANSYS FLUENT). The specified geometry, which corresponds to corrosion test samples exactly, is discretized using a body‐sizing meshing approach, comprising mainly of tetrahedron cells. Refinements were concentrated at the connection points between the layers to shift the focus toward the static effects dissipated between them. A detailed grid independence study is conducted to confirm the accuracy of the selected mesh densities. The momentum and energy equations were solved, and the viscous heating option was applied to represent the improved thermal physics of heat transfer between the layers of the structures. A discrete phase model (DPM) in ANSYS FLUENT was used, which allows for the injection of continuous uniform air particles onto the model, thereby enabling an option for calculating the corrosion factor caused by hot air injection. Extensive visualization of results is provided. The simulations show that ceramic (silicon carbide) when combined with titanium clearly provide good thermal protection; however, the ceramic coating is susceptible to cracking and the titanium coating layer on its own achieves significant thermal resistance. Higher strains are computed for the two‐layer model than the single layer model (thermal case). However even with titanium only present as a coating the maximum equivalent elastic strain is still dangerously close to the lower edge. Only with the three‐layer combined ceramic and titanium coating model is the maximum equivalent strain pushed deeper towards the core central area. Here the desired effect of restricting high stresses to the strongest region of the gas turbine blade model is achieved, whereas in the other two models, lower strains are produced in the core central zones. Generally, the CFD analysis reveals that maximum erosion rates are confined to a local zone on the upper face of the three‐layer system which is in fact the sacrificial layer (ceramic coating). The titanium is not debonded or damaged which is essential for creating a buffer to the actual blade surface and mitigating penetrative corrosive effects. The present analysis may further be generalized to consider three‐dimensional blade geometries and corrosive chemical reaction effects encountered in gas turbine aero‐engines.

Mathematical Modeling of Wax Deposition in Field-Scale Crude Oil Pipeline Systems

“…The end product is an accurate prediction of both the wax-deposit growth rate and aging (or hardening) of the deposited layer, which is essential for the design of pigging operations to achieve optimum pigging frequency and minimize operational costs. Some specific applications to the present study are the studies by Kadir et al [16], Anwar Beg et al [17], and Kuharat et al [18].…”

Investigation of Heat Transfer from Convective and Radiative Stretching/Shrinking Rectangular Fins

“…However, the Nusselt number increases considerably, and the influence is enhanced at very low high Rayleigh numbers. A finite-element model is used to investigate the thermal efficiency of varnishes in high-temperature gas turbine blade protection [21]. Based on the thermal results, the coating strains seemed to be controlled by the strain state of the building element near the coating interface.…”

Numerical simulation for the steady nanofluid boundary layer flow over a moving plate with suction and heat generation

“…Though it does not permit the stimulation of spectal effects or optical viscosity, but provides an evaluating mechanism for the relative role of heat flux radiation and heat conduction. Numerous scholars have investigated radiative heat transfer in materials processing including Shamshuddin et al [3] (bio convection nanofluid), Kadir et al [4] (thermal stress analysis), Liu et al [5] (multi laser processing) and Yue and Reitz [6] (internal combustion energies).…”