Ain Shams Scholar Collection:

Effect of the Radial Swirler Ellipticity on Hydrogen Flames in a Micro-Gas Turbine Combustor

Thu, 01 Jan 2026 00:00:00 GMT

Title: Effect of the Radial Swirler Ellipticity on Hydrogen Flames in a Micro-Gas Turbine Combustor Authors: Hassan, M. H.; Hamid, M. A.; Kinawy, M.; Kamal, M. M.; Ahmed Taher Hussin Abstract: A radial swirler burner with an elliptic cross section has been developed for a micro-gas turbine combustor that is commissioned to accommodate hydrogen combustion in the premixed flame mode. A numerical model has been established to explore the swirling combustion performance using the partially premixed flamelet-generated manifold combustion model via employing detailed chemical kinetics. The swirler cross-section aspect ratio has been varied in the range from 1 to 2 at a vane angle of 40 degrees, while the combustion performance was investigated for both fuel conditions of pure hydrogen and 50%/50% hydrogen-methane blend at full load and 50% load. While the results demonstrated the key flow field features, the flame shape as well as the exhaust NOx and CO emissions, it was found that increasing the aspect ratio significantly increased the turbulent kinetic energy and the resultant flow strain. Increasing the aspect ratio additionally increased the peak reverse flow velocity. Inasmuch as this was associated with higher rates of excess air entrainment, the peak flame temperature and the corresponding NOx emissions were reduced on the account of increasing the total pressure drop particularly at the maximum aspect ratio. In this regard, the NOx and CO emissions, respectively, decreased by up to 33% and 46.6% at the aspect ratio of 2.0. As driven by the highly strained reactive swirling flow, the hydrogen-methane premixed flame acquired extension in the flame stability limits. This was accompanied by a consequent reduction in the flow residence time and species re-distribution for NOx formation. The elliptic cross-section radial swirler has thus been proven to be an innovative flow configuration which effectively improves the combustion performance and reduces the resultant emissions.

Enhancing Fatigue Performance of Additively Manufactured H13 Tool Steel through Surface Finishing Processes

Thu, 01 Jan 2026 00:00:00 GMT

Title: Enhancing Fatigue Performance of Additively Manufactured H13 Tool Steel through Surface Finishing Processes Authors: Atef Hamada; Ahmed W. Abdel-Ghany; Matias Jaskari; Hassan Hosseinlou; Mohsen Shakeri; Antti Järvenpää Abstract: This study investigates the fatigue performance of additively manufactured H13 hot work tool steel (AM-H13 TS) produced using the laser powder bed fusion (L-PBF) process with two distinct build orientations: vertical (V-BO) and diagonal with 45° (D-BO). A fixed volumetric energy density of 57.3 J/mm3 was employed for fabrication. The study compares the as-built AMH13 TS to its surface-finished counterpart, focusing on fatigue life and damage under fully reversed tension-compression loading conditions. The surface finishing processes involved electropolishing using commercial DLyte 100HF+ equipment, followed by mechanical surface refinement. The surface topography and roughness characteristics of the as-built and post-polished specimens were comprehensively analyzed using laser confocal scanning microscopy (LCSM). Scanning electron microscopy (SEM) was utilized to examine the microstructural features and fatigue mechanisms. The as-built AM-H13 TS exhibited high surface roughness due to the presence of satellites and partially melted particles, which are inherent to the L-PBF process. The surface-finishing approach substantially mitigated these surface imperfections, resulting in significantly improved surface quality and reduced roughness. As a result, the fatigue performance of surface-finished AM-H13 TS showed remarkable enhancement. The fatigue limit increased fivefold, from 100 MPa in the as-built condition to 500 MPa after surface finishing. SEM analysis revealed that the improved fatigue strength was primarily attributed to the reduction in surface roughness and the elimination of surface flaws, which acted as crack initiation sites in the as-built condition.

Role of Mo and Zr Additions in Enhancing the Behavior of New Ti–Mo Alloys for Implant Materials

Mon, 01 Jan 2024 00:00:00 GMT

Title: Role of Mo and Zr Additions in Enhancing the Behavior of New Ti–Mo Alloys for Implant Materials Authors: Ahmed H. Awad; Modar Saood; Hayam A. Aly; Ahmed W. Abdel-Ghany Abstract: The utilization of Ti–Mo alloys in biomedical applications has gained attention for use in biomedical applications owing to their non-toxicity, reasonable cost, and favorable properties. In the present study, Ti–12Mo–6Zr and Ti–15Mo–6Zr alloys were prepared using elemental blend and mechanical alloying techniques. The effect of alloying elements Mo and Zr of Ti–Mo alloy, as well as the effect of fabrication techniques of Ti–Mo–Zr trinary alloys, were investigated. Thermodynamic calculations supported by CALPHAD analysis revealed that the addition of Zr increases lattice distortion, which contributes to enhancing the strength. Conversely, adding Mo decreases the enthalpy, facilitating improved mixing and solid solution formation. The as-sintered samples were characterized by X-ray diffraction, optical microscope, and scanning electron microscopy, and their microhardness, compressive, and corrosion behavior were investigated. Among all the investigated alloys, Ti–15Mo–6Zr alloy prepared by the mechanical alloying technique, milled for six hours at 300 rpm, compacted at 600 MPa, and sintered at 1250 ℃, shows good comprehensive mechanical properties with a preferable compressive strength (− 1710 MPa) and hardness (396 HV5), as well as the lowest wear rate (0.69%) and corrosion rate (0.557 × 10–3 mm/year). This can be related to the solid solution strengthening and relative density, together with dispersion and precipitation strengthening of the α phase. Remarkably, the combination of high mechanical and corrosion properties can be achieved by tailoring the content of the α phase, controlling the density, and providing new fabricating techniques for β Ti alloys.

Correlating zirconium incorporation and thermomechanical processing with the metallurgical properties of Ti-14Mn-(x)Zr alloys

Tue, 01 Jul 2025 00:00:00 GMT

Title: Correlating zirconium incorporation and thermomechanical processing with the metallurgical properties of Ti-14Mn-(x)Zr alloys Authors: Ahmed H. Awad; Matias Jaskari; Antti Järvenpää; Mohamed Abdel-Hady Gepreel; Ahmed W. Abdel-Ghany Abstract: The current study shows the effect of thermomechanical processing on the microstructure, deformation mechanism, tensile properties, and corrosion behavior of Ti-14Mn-(0–6 wt%)Zr alloys. The alloys were subjected to hot rolling at 900 °C following 30 min of reheating, with an approximately 80 % reduction and subsequent water quenching. The as-cast alloys exhibited a dual-phase (α' + β) structure, while the hot-rolled alloys were indexed for a single β phase. Electron backscatter diffraction (EBSD) analysis revealed a random texture indicative of a slip deformation mechanism. Tensile tests were conducted on both as-cast and hot-rolled alloys. The as-cast alloys experienced an early fracture within the elastic zone, attributed to coarse grains. Conversely, hot-rolled alloys exhibited commendable strength and moderate ductility, with strengths ranging from ∼1026 to ∼1106 MPa and elongation values from ∼1 to ∼6.5 %. The observed hardness and strength increase with Zr addition can be attributed to solid solution strengthening and grain refinement. The hot-rolled Ti 14-6 alloy exhibited the highest hardness at 403 HV2, accompanied by a yield strength (YS) of 1015 MPa, ultimate tensile strength (UTS) of 1106 MPa, and the lowest corrosion rate recorded at 12.3 × 10⁻³ mm/year.