In recent years, more and more attention has been paid to research on variable geometry turbine engines with the increasing requirement of engine performance. Variable geometry turbine technology can significantly improve the operating performance of aero engines. Adjusting the working angle of the turbine guide vane can change the thermodynamic cycle of the engine operation, so that the turbine can respond to different engine operating conditions. Variable geometry turbines work in harsh environments. Therefore, the design of the variable geometry turbine needs to consider the effect of thermal deformations of the mechanism on operational stability. There are few research studies on variable geometry turbine adjusting mechanisms. This paper established the numerical calculation models of two adjusting mechanisms by integrating fluid mechanics, heat transfer, and dynamic theories, which are paddle and push–pull rod mechanisms. The models were applied to study the effects of components’ thermal deformations and flexible bodies on the motion characteristics of the adjusting mechanism. Furthermore, the performance of the two adjusting mechanisms was compared. The calculation results show that the paddle rod adjusting mechanism can accurately adjust the angles of guide vanes. The paddle rod adjusting mechanism has a larger driving stroke and smaller driving force than the push–pull rod adjusting mechanism. The paddle adjustment mechanism was better suited to the operational requirements of the variable geometry turbine. The research results of this paper are relevant to the design of variable geometry turbine regulation structures.

In this paper, a set of partial differential equations considering the dynamic effects of the coiled tubing (CT) is established based on the bending theory of slender beams considering the axial loads. The analytical solution of sinusoidal deformation with the time term is obtained. The critical load of coiled tubing during sinusoidal buckling and the change of half-wave number during sinusoidal post-buckling are studied through the introduction of the necessary conditions, solution and the separation constant. The contact force of coiled tubing with sinusoidal post-buckling on the horizontal well wall is analyzed. The results show that the critical load for sinusoidal buckling of fixed-size CT is related to the section angular acceleration coefficient. The half-wave number produced by the sinusoidal post-buckling bending of the CT gradually decreases during compression. The contact force of the deformed CT to the borehole wall is related to the compression speed of the CT. By introducing the dynamic term and the separation constant, this research model can provide a theoretical basis for studying the transformation of the CT from sinusoidal buckling to helical buckling.

More and more attention has been paid to research on variable geometry turbine engines with the increasing improvement of performance requirements for military turbines. Due to the fixed working angle of the inlet guide vane, the performance of a conventional fixed geometry turbine is optimal only for turbines near the design point. To match the aircraft’s starting, climbing, cruising, deceleration, landing and other working states, it is necessary to change the turbine speed. This will not only reduce the performance of the turbine but also increase the fuel loss. The variable geometry turbine is a perfect solution to this problem. It is not necessary to change the speed of the turbine, but only the working angle of the inlet rotating guide vane of the turbine. The variable geometry turbine can be matched to each state of the aircraft’s entire voyage. The turbine guide vane can be adjusted by 7° to bring about a 10% change in the flow rate of the entire machine. With constant turbine inlet temperature, the fuel loss can be effectively reduced. The rotating guide vane is impacted by the high-temperature and high-pressure gas and cold air in the inner culvert. Hot and cold air produce two types of aerodynamic torque on the rotating guide vane. There is also a friction torque on the rotating shaft of the guide vane. Therefore, the rotating guide vanes of variable geometry turbines are subjected to three types of torques. The main objective of this paper is to study three factors influencing the guide vane torque in the main flow path. The three influencing factors are the turbulence intensity of the gas, the flow ratio of cold gas to hot gas and the location distribution of the gas film holes on the guide vane. In this paper, CFD temperature-fluid-solid coupling algorithm combined with UDF program is applied to solve the torque of guide vane shaft at three influencing factors. The results show that the three factors, turbulence intensity, flow ratio and air film hole distribution, can have a significant effect on the guide vane torque. This is of great significance for the research and design of variable geometry turbines.

Blast Furnace (BF) is the primary production equipment for modern ironmaking, and the hearth is a crucial part of the BF where high-temperature molten iron is periodically stored. The deadman, located within the hearth, poses a significant obstruction to the flow of molten iron. Changes in the state of the deadman directly affect the flow and discharge behavior of molten iron within the hearth, subsequently influencing the lifespan of the hearth. This study develops a three-dimensional Computational Fluid Dynamics (CFD) model that incorporates the flow of molten iron and the solidification phase transition within the blast furnace hearth. Using the skull’s thickness in the erosion area as an evaluation index, it investigates the effects of deadman parameters, such as floating height, maximum diameter, eccentricity, porosity, and bottom shape, on the hearth’s erosion area. Additionally, considering the iron flow velocity and furnace wall temperature, the study offers suggestions for the comprehensive protection of the furnace hearth. The findings revealed that maintaining a higher floating height of the deadman is beneficial for the comprehensive safety of the hearth. When the deadman is eccentric towards the erosion direction, its volume increases, or its porosity decreases, the thickness of the skull in the erosion area will decrease, posing potential safety hazards to the operation of the BF hearth. The deadman with a spherical bottom, in both its seated and floating states, results in a stable thickness of the skull in the erosion area, which is favorable for extending the service life of the hearth.

Coke morphology modulates multiphase transport in raceway flows by influencing thermo-fluid behavior and heat transfer performance. This study employs the Discrete Element Method–Computational Fluid Dynamics (DEM–CFD) approach to analyze the effects of particle shape on raceway structure and heat transfer. The applicability of the method was validated against experimental data, and the accuracy of the Coarse-Grained Particle Model (CGPM) was assessed. Comparative analysis revealed particle shape effects on raceway dynamics. Results indicate that CGPM significantly reduces computational costs while preserving dynamics and thermodynamics consistent with those of the original particle systems in raceways. Spherical and pyramidal particles form enlarged raceways, facilitating deadman formation through accumulation at the furnace hearth center. In contrast, three other non-spherical morphologies reduce raceway dimensions yet enhance convective heat transfer. Ellipsoidal particles suppress temperature rise, while pyramidal particles induce fragmented fluidization at the raceway top with velocity-dependent instabilities. Raceway size inversely correlates with drag force and heat transfer rate. These findings advance the understanding of dynamic and thermo-fluid behaviors of non-spherical particles in raceways.