Shearer traction failure occurs frequently, which seriously restricts the safe and efficient mining of coal. However, the influence of the shearer’s posture on traction has not been fully considered in the existing research. To improve traction reliability: the dynamic model of the traction unit is established considering longitudinal swing; the walking characteristics of the shearer and the dynamics of the traction unit are analyzed; and the influences of traction velocity, drum load cutting arm angle, and depression angle are discussed. The results show that the longitudinal swing is reciprocating and the positive swing is more serious. With the increase of the traction velocity, the walking stability of the shearer decreases while the contact force increases, especially the support slipper. The longitudinal swing increases with the increase of lateral load, but the supporting force of the support slipper decreases with the increase of cutting load. The forces of the walking wheel and the support slipper show an increasing trend with the increase of cutting arm angle. When the depression angle is 5–10°, the load distribution of the contact components of the traction unit is more balanced. The results provide a reference for the structure optimization of the shearer and the layout of coalface.

To improve the dry powder jet extinguishing efficiency, the velocity change and spatial distribution of ultrafine dry powder particles under the action of high Mach number compressible air are studied by using the SST k-omega turbulence model and the gas-solid two-phase coupled model. The effects of nozzle pressure ratio, particle diameter, and mass flow on parameters such as Mach number and radial diffusion width are analyzed,and the influence of injection pressure and jet performance is verified by ultrafine dry powder jet experiment. The results show that the increase in the particle size will weaken particle flowability; the Saffman lift force has a significant effect on the particles when the nozzle expansion angle is large, and a particle-free zone is produced near the center axis; increasing the nozzle pressure ratio or reducing the dry powder mass flow rate will help improve the particle velocity in the core jet area outside the nozzle, and the accuracy of this law is proved by experiments. These findings are expected to provide valuable insights for the design of fire extinguishing nozzle structures.

The nozzle, converting pressure into kinetic energy, is the key component of fire extinguishing equipment, and its structure seriously affects the jet performance of fire monitors. In this study, the three-phase jet fire monitor (TPJFM) nozzle is taken as the research object, and the primary structural dimensions of the nozzle’s internal flow channel are considered as design parameters. A multi-objective optimization approach is employed to minimize the average turbulent kinetic energy at the outlet of the nozzle internal flow channel and the pressure drop between the inlet and outlet of the nozzle internal flow channel by integrating the Kriging surrogate model and NSGA-II. The research results indicate the pressure drop between the inlet and outlet of the nozzle internal flow channel decreases by 3.48%, and the average turbulent kinetic energy at the outlet of the nozzle internal flow channel reduces by 29.38% after optimization. The flow velocity distribution at the outlet of the internal flow channel of the optimized nozzle is more uniform, with an increase in jet range by 6.25%. Reasonable optimization of nozzle structure can significantly improve jet performance, and this method can provide a reference for designing nozzle structures.

To enhance the jet performance of the three-phase jet fire monitor (TPJFM), an analysis was conducted on the internal flow field (IFF) characteristics of the monitor head. Using the volume of fluid method, the impact of key structural parameters, such as the powder-pipe bending angle and the supporting blade length, on the turbulent kinetic energy (TKE) of the IFF, the velocity distribution uniformity at the nozzle outlet, and the pressure drop (PD) between the inlet and outlet of the internal flow field, was analyzed. The study revealed that increasing the bending angle of the powder pipe will lead to a significant improvement in the uniformity of velocity distribution in the IFF. Extending the supporting blade length helps reduce the average TKE at the nozzle outlet but has a minimal impact on the velocity distribution uniformity and the PD between the inlet and outlet. Reasonable design of the distance between the supporting blades and the bending section of the powder pipe can improve the IFF characteristics, reducing local pressure losses and peak TKE. The research results can effectively improve the IFF characteristics, enhance jet performance, and provide theoretical basis and technical support for the design and optimization of the TPJFM.

As a critical component of the three-phase jet fire monitor head, the nozzle efficiently converts fluid pressure energy into kinetic energy. Optimizing its structural parameters is essential for enhancing jet performance and firefighting efficiency. This study investigates the internal flow field of the nozzle using the VOF method, examining the influence of various structural parameters. The research systematically examines the effects of the nozzle outer wall contraction angle, powder nozzle expansion angle, and length of the nozzle straight section on the internal flow field characteristics. Results indicate that when the nozzle outer wall contraction angle exceeds 25°, the velocity uniformity at the nozzle outlet deteriorates significantly, average turbulent kinetic energy at the outlet of the nozzle increases to 2.37 m²/s², and the pressure drop between the inlet and outlet of the nozzle increases by 1.38%. When the powder nozzle expansion angle exceeds 30°, intensified collision of water flow at the entrance of the straight section further elevates turbulent kinetic energy and pressure drop. The length of the nozzle straight section of 20 mm minimizes turbulent kinetic energy to 1.843 m²/s², achieving optimal flow rectification. The findings suggest that rational adjustment of nozzle structural parameters can significantly improve internal flow field characteristics and provide a theoretical basis for structural optimization of the three-phase jet fire monitor.

To characterize the dynamic behavior of the hydraulic system of a ground coal-bunker cleaning device under variable operating conditions, a mechanical–hydraulic co-simulation model was established by coupling ADAMS and AMESim. A pipeline pressure-drop model accounting for distributed frictional, local, and coiling-induced losses was developed based on the Darcy–Weisbach equation. The effects of the number of rod sections, hydraulic-hose length, valve-group actuation interval, and the equivalent hose-coiling state were evaluated. Increasing the rod sections from 1 to 30 raised the steady-state pressure of the lead-screw lifting motor by 42.0%, reduced its flow rate by 26.9%, and increased the pressure settling time by 167.2%. Increasing the hose length from 5 to 20 m reduced cylinder pressure from 25.20 to 11.30 bar and the pressure synchronization coefficient from 0.966 to 0.775. A 0.5 s valve-group interval reduced the composite disturbance by approximately 54%. At the representative flow rate of 22.59 L/min, the calculated total pressure loss increased from 0.664 MPa for the one-layer state to 0.742 MPa for the nine-layer state, an increase of approximately 11.7%, while frictional loss remained the dominant component. For different working conditions, finite-range sensitivity comparisons identified reflected inertia and load torque, hydraulic capacitance and distributed flow resistance, temporal overlap of branch flow demand, and distributed pipeline friction as the response-specific drivers of the four investigated operating scenarios. The model and results can provide a basis for optimizing actuation timing, hose layout, and operating strategies for coal-bunker cleaning devices.