Abstract

The Large-Eddy Simulations (LES) play an important role in the study and design of gas turbine combustors. In order to bring the cost of LES down, compact high-order accurate solvers that can handle complex geometry are a promising method. However, their accuracy vs cost benefit as compared to the standard finite-volume solvers is unclear when it comes to under-resolved hybrid unstructured meshes. These meshes are required to represent the industrial combustor geometries. In this work, a high-order spectral/hp (Nektar++) solver is compared to a standard finite-volume (OpenFoam) solver for a fixed cost. Two combustor-relevant configurations are employed, port-flow and swirling flow. It is found that high-order solver provides moderate accuracy improvements in terms of the mean results and significant improvements for the unsteady results.

Abstract

Reducing the extraction of natural resources is a current demand in the construction industry. Studies show that eggshells are rich in calcium carbonate and have the potential to replace limestone in lime production. In this context, the objective of this article is to use an eggshell lime produced in the laboratory to stabilize a residual clayey soil and compare the unconfined strength of the admixtures with others using commercial dolomitic lime. Different lime contents and porosities were evaluated and the porosity/lime ratio was studied to understand the unconfined strength behavior of admixtures. In addition to the soil and limes characterization tests, X-ray diffraction tests were carried out to analyze the chemical and mineralogical composition of the materials. The results showed that increasing lime content and decreasing porosity increased unconfined strength. Also, the unconfined strength achieved with the eggshell lime was greater than that achieved with dolomitic lime for the same lime content. The X-ray diffraction tests showed that the eggshell lime is composed almost entirely of calcium hydroxide, and microscopic images demonstrated much stronger bonds in the final product obtained from eggshell lime. The porosity/lime ratio was a good parameter for evaluating unconfined strength. A unique relationship was achieved linking unconfined compressive strength with the porosity/lime ratio for both the eggshell and the dolomitic lime mixtures.