The growing demand for low-carbon building materials and the challenges of handling agroforestry waste and discarded EPS particles have spurred research toward developing novel building composites that utilize solid waste. Therefore, this study aims to develop a lightweight geopolymer composite incorporating these recycled materials to balance thermal insulation, mechanical strength, and waterproofing properties. In this work, geopolymer served as the binder, with various types of raw biomass (sawdust, rice husk, rice straw, and coconut fiber) as the primary aggregates and EPS particles as an additive to create a closed-pore structure. The microstructure of the raw biomass was characterized by SEM, while its specific surface area and average pore diameter were determined by BET analysis. Furthermore, the prepared composites were comprehensively evaluated in terms of their microstructure, pore structure (MIP), density, thermal conductivity, compressive strength, total water absorption, capillary water absorption, surface wettability, and UV aging behavior. The results showed that the prepared composites exhibited a porosity of 59.9–65.7%, a density of 492.9–586.3 kg/m³, a compressive strength of 7.3–10.9 MPa, a thermal conductivity of 0.115–0.142 W/(m·K), a total water absorption of 35.2–42.2%, capillary water uptake coefficients of 4.9–11 kg/m², and a water contact angle exceeding 140° (after modification). In addition, the developed composites offered significant environmental and economic benefits, with a low carbon footprint and an estimated cost of 100.6–150.3 USD/m³, making them more competitive compared to traditional insulation materials. Meanwhile, this study provides a scientific basis for developing high-strength building insulation materials from agroforestry waste, thus outlining a promising direction for future research and industry development.

Ventilation and dust removal systems in industrial buildings handle particulate-laden exhaust flows. Centrifugal fans are the primary gas-moving equipment in these systems, and straight plate blades are widely used in them. These blades resist particulate deposition and erosive wear. Their aerodynamics are governed by the inlet clearance between the stationary inlet nozzle and the rotating impeller. Design and simulation routinely idealize it as clearance-free. A 12-blade fan of this type was studied numerically. Four clearance conditions were quantified over the full flow range. This idealization overestimated the design point total pressure efficiency by 1%. Overlapped clearance dominated the aerodynamic performance. A clearance of 20 mm approached the original model. A clearance of 30 mm, in contrast, reduced the efficiency to 50% at high flow. The axial clearance itself lowered the total pressure efficiency. Its size, however, barely mattered. The three axial clearance models remained within 77–78% at the design flow rate. A circumferentially non-uniform clearance lowered the design point efficiency to 79% and the high-flow efficiency to 32%. Eddy viscosity accumulation and passage blockage show that leakage-induced backflow sets these limits. These results provide a basis for controlling inlet clearance tolerances during the design and assembly of the straight plate blade fans.

The axial compressor is crucial for heavy-duty gas turbines, with its aerodynamic performance directly affecting efficiency. The current trend in the development of these compressors is to increase the stage load and efficiency, thereby achieving a higher pressure ratio with fewer stages. The aerodynamic characteristics of a 1.5-stage axial compressor from a 300 MW F-class heavy gas turbine at three different rotation speeds (100%, 90%, and 80%) were studied. Specifically, the distribution of the inlet Mach number, shock wave structures, isentropic Mach number of blade surface, and blade surface separation flow characteristics under three typical working conditions, at the near stall (NS) point, maximum efficiency (ME) point, and near choke point (NC), were discussed. The results indicate that at 80% rotational speed, 70~100% spanwise of the compressor rotor blade is operated under the transonic zone. Meanwhile, at 100% rotational speed, almost all the spanwise of the compressor rotor blade is operated under the transonic zone. Furthermore, compared to the detached shock wave observed under the NS condition, the normal passage shock wave observed under the NC condition exhibits more significant changes in shock intensity and shock pattern.