To improve the performance of the adjustable jet pump，the end protrusion structure of the conventional needle head was changed to a streamlined structure with smooth circular arc connections，in order to reduce the disturbance of the needle to the working fluid.Numerical simulations were conducted for adjustable jet pumps with conventional needles and streamlined needles under different nozzle opening conditions to study the influence of needle shape on energy transfer efficiency and the internal flow field.The results show that compared with the conventional needle，the streamlined needle has a smoother flow channel inside the nozzle，which can better improve the flow conditions of the needle and nozzle，thereby facilitating jet energy transfer；The overall efficiency of the adjustable jet pump in the streamlined injection needle is improved，with an increase of about 2.5% when the nozzle opening is 50.41%，and the relative head loss of the nozzle can be reduced by 5.19%.At the same time，the streamlined injection needle can improve the pressure distribution in the nozzle. Under the conditions of nozzle opening of 50.41% and flow ratio of 0.4，it ensures a minimum negative pressure calculation value of approximately -89 kPa，avoiding that excessively low pressure and cavitation occur inside the nozzle..The research results can provide references and basis for the structural design and performance improvement of adjustable jet pumps.

To address the efficiency bottlenecks in in‑tube methanol reforming for hydrogen production，a design method for structured catalyst supports based on 3D printing technology was proposed.Numerical simulations of heat transfer and fluid flow were conducted at a Reynolds number （Re） of 140 to compare three channel structures：straight channels，zigzag channels，and helical channels.Taking the straight channel as the reference model，the reaction performance was thoroughly investigated，and a numerical calculation model was established （with deviations of ≤5% for methanol conversion and ≤0.6% for CO selectivity）.Structural screening of the three configurations was completed via model predictions and experimental validation.Results indicate that the helical channel exhibits the highest Performance Evaluation Criterion （PEC） value of 14.7.Both methanol conversion and CO selectivity in the methanol reforming reaction increase with increasing temperature and decrease with rising volumetric flow rate.Both model predictions and subsequent screening experiments confirm that the helical channel maintains optimal performance.Specifically，experimental data show that the methanol conversion of the helical structure reaches 65.8%，which is 11.4% and 24.4% higher than that of the zigzag channel and straight channel，respectively.This study provides a theoretical basis for the design of 3D‑printed catalyst supports.

To investigate the flow characteristics and multi‑field coupling mechanisms inside the twin‑screw pump.Based on the Eulerian-Eulerian heterogeneous flow model and the immersed boundary method，a transient simulation of the flow field in a multiphase twin‑screw pump was conducted under varying gas volume fraction conditions.The variations in pump outlet flow rate，pressure，phase distribution，and rotor surface velocity were analyzed.The fluid pressure was applied to both the rotors and the liner to obtain the laws of radial，circumferential，axial deformation and stress-strain of the rotors and liner.Furthermore，the pressure at monitoring points was compared with experimental data，validating the accuracy of the results.The results indicate that the outlet flow rate initially increases and subsequently decreases with the rising gas volume fraction，reaching its maximum value at a gas volume fraction of 50%.The pressure exhibits a step‑like increase from the inlet to the outlet，remaining nearly constant within individual cavities.The gas volume fraction exhibits a positive correlation with the pressure‑boosting capacity of the last‑stage screw.The gas phase predominantly accumulates in the screw roots，near the outlet edges，and at the intermeshing zones of the screw rotors throughout the flow passage.The liquid phase exhibits relatively higher velocities at the outlet，the meshing region between the driving and driven screw rotors，and near the screw tips.The radial and circumferential deformations of the rotor reach their maximum at the outlet.Under a gas volume fraction of 95%，the maximum radial and circumferential deformations reach 3.501 7×10⁻⁶ m and 3.603 7×10⁻⁶ m，respectively.The radial deformation of the liner reaches its maximum at the outlet and exceeds the deformation values in all other directions.The structural strength of both the rotors and the liner meets the requirements under all gas volume fraction conditions.The gas volume fraction influences the pump's outlet flow rate，internal pressure distribution，gas‑phase distribution，liquid‑phase velocity，and structural deformations；however，it does not affect the structural strength of the rotors and the liner.This study can provide valuable insights for optimizing the geometric profile design of the rotors and clearance control of twin‑screw pumps，thereby effectively enhancing their transportation efficiency and operational stability under multiphase flow conditions.

To address the effective degassing problem of oil-air mixtures in aero‑engine lubrication systems，a dynamic pressure oil-gas separator with a square inlet and simple compact structure is proposed.A combination of simulation and experimental methods was used to analyze its separation performance，and the control variable method was applied to investigate the influence laws of flow velocity，oil volume fraction，and oil droplet size on separation efficiency.The results show that the separation efficiency of the oil-gas separator is highest under high flow velocity and low oil volume fraction conditions；flow velocity has a significant impact on separation performance，achieving a maximum air separation efficiency η_d of 88.8% at 35 m/s；oil volume fraction also notably affects separation performance，reaching a maximum oil separation efficiency η_c of 93.5% at an oil volume fraction of 5% and droplet size of 5 μm.For large droplets with sizes of 15 μm and above，the separation efficiency η_k of this dynamic pressure oil-gas separator approaches 100%.This study can provide references for the development of oil-gas separators with high separation efficiency and low flow resistance.

Leakage research in scroll compressors is crucial for their theoretical simulation，structural design，and performance analysis.This paper introduces two main leakage pathways in scroll compressors，reviews research achievements by domestic and international scholars，analyzes and compares leakage calculation models based on 3D CFD and 1D simulation，and discusses property mixing methods when considering lubricating oil.For 3D leakage calculations，studies mostly use software such as Fluent，CFX，PumpLinx，and Simerics MP+，primarily focusing on performance optimization or impact through structural modifications；1D calculations mainly employ modified nozzle models，parallel plate flow models，incompressible viscous flow models，etc.，emphasizing performance improvement and model prediction accuracy，with most models requiring experimental correction and having specific applicable operating ranges.The research results indicate that clearance size significantly affects leakage outcomes，while channel shape，roughness，and lubricating oil also influence leakage behavior；when considering lubricating oil，the working fluid and oil are typically treated as a homogeneous mixture.Regarding sealing method improvements，theoretical and experimental research can be conducted on novel flow structures.In terms of different research approaches，future 3D CFD simulations could develop towards systematization，fluid‑structure coupling，and integration with reverse engineering and artificial intelligence；1D simulations should incorporate heat transfer and variable working fluid conditions，further optimizing leakage predictions by combining Fanno flow models，oil‑containing conditions，and two‑phase flow models.This study can provide references for the development and performance optimization of scroll compressors.

To achieve accurate measurement of residual propellant in on‑orbit satellites，based on thermal‑fluid‑structure coupling calculation method，numerical calculations were conducted on the transient flow and heat transfer characteristics of propellant during heat capacity measurement.The flow characteristics，temperature distribution，and heat flux distribution characteristics of propellant in the tank under different settling acceleration conditions were analyzed.By comparing real‑time temperature change data from simulation and experimental monitoring points，the accuracy of the numerical calculation model was verified.The results show that the sloshing frequency of liquid propellant in the tank increases with increasing settling acceleration.When settling acceleration increases from 0.066 5 m/s² to 0.294 m/s²，the propellant sloshing frequency increases from 0.055 Hz to 0.116 Hz.The temperature change of fluid above the gas‑liquid interface is more significant compared to that below the interface.After continuously heating the tank surface at 180 W total power for 180 seconds，there exists a certain temperature difference between the outer wall of the tank and the fluid‑structure interface，with an average temperature difference of 0.12 K.The lower the monitoring point position，the slower the temperature rises.The main frequency of temperature change at monitoring points inside the tank is consistent with the variation in liquid propellant sloshing frequency.The research results can provide references for the measurement of residual propellant quantity in on‑orbit satellites.

To investigate the influence of operating parameters on the atomization performance of external‑mix air‑atomizing nozzles and determine the optimal operating parameters for achieving the best atomization effect，a combined method of finite element model construction and optimization calculation was adopted for relevant research.Using gas inlet pressure，liquid inlet pressure，and liquid kinematic viscosity as optimization variables，and atomization cone angle and outlet flow coefficient as optimization objectives，an orthogonal experiment was designed and conducted.Based on the orthogonal experimental data，a response surface surrogate model was established，and this surrogate model was optimized using genetic algorithm，followed by simulation verification and comparative analysis of results.The results show that gas inlet pressure，liquid inlet pressure，and liquid kinematic viscosity all have significant effects on nozzle atomization performance；when the gas inlet pressure is 0.057 2 MPa，liquid inlet pressure is 0.111 2 MPa，and liquid kinematic viscosity is 0.057 3 Pa·s，the nozzle atomization performance reaches its optimum.Compared with the original model，the atomization cone angle increases by 34.62%，and the outlet flow coefficient improves by 49.36%.The research can provide references for the setting of operating parameters for nozzles.

To mitigate cavitation issues in low‑lift submersible axial flow pumps during operation，a method inspired by the use of circumferential groove casing treatment for stability enhancement in compressors was proposed. This approach involved applying circumferential groove casing treatment to axial flow pumps. Seven different casing treatment schemes were designed，and their effects on the cavitation performance of the pump were investigated through steady-state numerical simulations using the SST k-ω turbulence model and the Zwart-Gerber-Belamri cavitation model. The study focused on three key parameters：the installation position，width，and depth of the circumferential grooves.The results indicate that cavitation is primarily caused by low‑pressure regions formed by the leakage flow at the blade tip.After installing the circumferential grooves，the pump head experienced some loss，with the installation position of the grooves having the most significant impact on cavitation performance. Compared to a smooth wall casing，cavitation occurred earlier when the groove is positioned at 10% of the axial chord length，while the best anti‑cavitation performance is achieved when the groove is located at 45% of the leading edge of the axial chord length at the blade tip，reducing the required net positive suction head （NPSH） by 2.9%. Among three groups of grooves with different widths，it was found that as the groove width increased，the pump's anti‑cavitation performance improved，with the maximum NPSH reduction reaching 4.01%，although this also led to increased head loss.Additionally，three grooves with different heights all resulted in a 2.9% reduction in NPSH，indicating that groove height has a relatively minor impact on cavitation performance. The findings of this study provide a theoretical basis for suppressing cavitation in water pumps.

In view of the problem that ice blockage is prone to occur when using supercooled water method make dynamic ice，propose a set of ice slurry production experimental device equipped with blades‑type super‑cooling releasing device.The test performance shows that the ice making system with blades‑type super‑cooling releasing solution can stably and continuous work when the concentration of NaCl solution is not less than 7%.The concentration of NaCl solution is maintained at 7%，change other working conditions such as the flow rate of the ice‑making solution，the initial temperature of the secondary refrigerant，the speed of the scraper，the maximum ice content of the ice slurry reach 21.6%.The ice slurry output of this ice slurry system can reach 1.40 ~3.48 kg/h.The time for continuous production of flowable ice slurry can be stabilized over 40 min.Compared with the spiral‑blade‑type super‑cooling releasing device，the blades‑type super‑cooling releasing device effectively solves the ice blockage phenomenon of the super‑cooler，and the continuous ice‑making time increases by 4.6 to 72.7 times.The blades‑type super‑cooling releasing device can provide guarantee for the continuous production of ice slurry in the ice making system.

In response to the problems of severe wear on the rolling cutter ring，difficult penetration，and reduced efficiency during the rock‑breaking process of the vertical shaft tunneling machine，this study conducts experimental research on abrasive water jet cutting of granite under submerged conditions，based on the rock‑breaking mechanism of ultra‑high pressure post‑mixed abrasive jet cutting.Focusing on the working condition of a 150 mm submerged depth for vertical shaft excavation，the influence laws of nozzle movement speed，jet pressure，and jet standoff distance on the rock‑breaking cutting effect were explored.The results show that the optimal matching parameters are a jet pressure of 380 MPa，a nozzle movement speed of 18 m/min，and a jet standoff distance of 20~40 mm；with these parameters，a maximum single‑cutting depth of 4.4 mm and a maximum cutting width of 2.3 mm can be achieved.Furthermore，a jet nozzle layout scheme for the full‑face vertical shaft tunneling machine cutterhead （with an excavation diameter of 8.1 m） is proposed.Through the collaborative layout of 26 jet nozzles，the rock‑breaking and tunneling efficiency of the full‑face vertical shaft tunneling machine can be effectively improved.The research results can provide certain references for the application of abrasive jet‑assisted rock breaking in vertical shaft excavation operations.