Amid rising industrialization and economic progress, China has shown exponential growth in energy and fossil fuel consumption; therefore, it faces great global concern and widespread criticism for energy and fuel conservation to reduce fuel-related emissions. In addition, the recent spread of COVID-19 instigates the impact of environmental pollution, exaggerates the virus intensity, and lowers people’s immunity due to poor air quality. Therefore, this study explored the role of green energy efficiency and climate technologies in achieving carbon neutrality in China using an advanced quantile autoregressive distributed lag (QARDL) framework. The results indicated that green energy efficiency and climate technologies significantly reduce environmental pollution across all quantiles in the long run. In contrast, urbanization enhances environmental degradation at lower and higher emissions quantiles, while trade only promotes environmental pollution at lower quantiles. These findings suggested using alternative energy sources and carbon-reducing technologies to ensure a sustainable environment.

This paper analyzes the environmental performance, spatial and temporal characteristics, and optimization paths of key polluting industries, represented here by the power industry, using the super-efficient MinDS model. The study shows that the environmental performance as a whole presents the characteristics of an inverted U-shaped and then a U-shaped trend; each region presents an asymmetric state of convergent development followed by differentiated development, with 2014 as the structural change point; the development trend of environmental performance in each region is divided into three categories (rising, falling, and stable) and four types of spatial clustering (ultra-high, high, medium, and low levels); and input–output indicators of environmental performance in China and across regions have varying degrees of redundancy, with labor input redundancy being the greatest, followed by capital input, technology input, and pollution emissions. On this basis, we propose to improve the monitoring and inspection mechanism of the implementation process of pollution control in key polluting industries and to improve the level of environmental performance of key polluting industries by optimizing the combination of labor, capital, and technology input factors in each region according to local conditions and adopting differentiated strategies. The main contributions of this paper are threefold: first, we incorporate technological inputs into the environmental performance evaluation index system of the electric power industry, which can better reflect the real inputs of the electric power industry and measure the results more accurately; second, we adopt the MinDS model for measuring the environmental performance level, which can quantitatively analyze the gap between each indicator and the optimal level; and third, we propose a redundancy index, which can be used to compare the redundancy of each indicator and then judge the main efficiency levels of the different factors.

In the typical structure of a turboshaft aero-engine, the mass flow of the cooling air in the rotor-stator cavity is controlled by the inlet seal labyrinth. This study focused on the swirl flow and heat transfer characteristics in a rotor-stator cavity with considerations of the inlet seal thermal deformation effect. A numerical framework was established by integrating conjugate heat transfer (CHT) analysis and structural finite element method (FEM) analysis to clarify the two-way aero-thermo-elasto coupling interaction among elastic deformation, leakage flow, and heat transfer. Simulation results showed that the actual hot-running clearance was non-uniform along the axial direction due to the temperature gradient and inconsistent structural stiffness. Compared with the cold-built clearance (CC), the minimum tip clearance of the actual non-uniform hot-running clearance (ANHC) was reduced by 37–40%, which caused an increase of swirl ratio at the labyrinth outlet by 5.3–6.9%, a reduction of the Nusselt number by up to 69%. The nominal uniform hot-running clearance (NUHC) was defined as the average labyrinth tip clearance. The Nusselt number of the rotating disk under the ANHC was up to 81% smaller than that under the NUHC. Finally, a clearance compensation method was proposed to increase the coolant flow and decrease the metal temperature.

The inertial particle separator (IPS) installed before a helicopter engine runs the risk of ice accretion. This paper describes a numerical study of ice accretion inside an IPS. The effects of the droplet diameter (MVD = 5, 10, and 20 µm), liquid water content (LWC = 0.5, 2, and 4 g/m3), and incoming velocity ( U0 = 45, 60, and 90 m/s) on ice accretion are studied. The results show that ice accretes on the windward side of the hub, the bent surface of the shroud, and the leading edge of the splitter. The ice thickness on all the surfaces of the IPS generally increases with increasing U0, MVD, and LWC, with the exception that the ice layer thickness on the splitter surface decreases as the MVD increases. This exception arises because the mass of water droplets impinging on the upper surface of the splitter wall decreases with increasing MVD. The effect of ice accretion on the aerodynamic performance of the IPS is also studied. It is found that ice accretion can block the flow area of the “throat” and the inlet of the scavenge flow channel, thus modifying the aerodynamic shape of the inner surface of the IPS and the internal flow field. When MVD = 10 µm and LWC = 4 g/m3, the scavenge ratio after icing decreases with increasing ice thickness. With the exception of LWC = 0.5 g/m3, the total pressure recovery coefficient of the core flow path of the IPS obviously decreases as the ice layer thickens.

The present paper reports an impingement/effusion cooling structure applied to the turbine casing. The structure consists of three rows of jet holes and two rows of effusion holes, both of which are in a staggered arrangement. A high rib exists inside the impinging chamber for structural support, which is connected to the effusion plate and divides the impinging chamber into two interconnected small chambers, one of which is arranged with effusion holes and the other is not. Transient liquid crystal (TLC) experiments were conducted to investigate the influence of the Reynolds number based on the jet hole diameter (ReD), distance between impingement plate and effusion plate (H), hole pith in Y direction (A) and X direction (C), with a parameter range of 1100 ≤ ReD ≤ 5100, 2.5 ≤ H/D ≤ 7.5, 4.0 ≤ A/D ≤ 14.0 and 8.0 ≤ C/D ≤ 14.0, on the heat transfer characteristics of the effusion plate. The results show that the region averaged Nu increases with an increase in ReD for all studied cases and there is a linear relationship between the ReD and the region averaged Nu in the logarithmic coordinate. The change of H/D has an obvious effect on the heat transfer in the 2D-3D region from the stagnation point. As the H/D increases, the entrainment effect that makes the surrounding fluid continuously enter the jet, resulting in the velocity of the jet decreasing, and the enhanced heat transfer at the effusion plate becomes weaker. When 38 < Y/D < 42 and 0 < Y/D < 1, the Nu increases with the increase of H/D due to the weakening of the flow separation of the wall jet. The variation of A/D has little effect on the enhanced heat transfer in Region1 (surface without effusion hole), but for Regions2-4 (surface with effusion holes), decreasing or increasing A/D is unfavorable to the uniformity of the Nu distribution. The heat transfer enhancement is mainly influenced by C/D. As C/D decreases, the proportion occupied by the stagnation region gradually increases, thus the surface Nu increases significantly.