To address the issue of axial floating and angular deflection of the seal ring caused by changes in methane solubility and gas volume fraction in the oil phase within multiphase pumps，as well as slug flow impact，leading to seal ring wear failure，a transient dynamic model for oil-gas two‑phase flow lubricated sealing considering methane dissolution is established.The model is solved using the finite difference method and the Euler method.The transient response characteristics of the seal before and after considering methane dissolution are compared，and the effects of axial pulsation and angular impact on the seal under different gas volume fractions when considering methane dissolution are investigated.The results show that when methane dissolution is considered，the fluctuations in film thickness and leakage rate are smaller，and the opening force tends to be consistent；during stage Ⅱ of axial vibration，when the gas volume fraction is 0.8，the displacement of the stationary ring is reduced by 3.25 times compared to when the gas volume fraction is 0；the stationary ring is less affected by angular impact，with the maximum change in central film thickness not exceeding 0.1 μm；when the gas volume fraction ranges from 0 to 0.8，the response of sealing performance to axial pulsation follows the same pattern；when the gas volume fraction is 0，the impact of angular shock on sealing performance is relatively small.This study provides theoretical guidance for the application of oil-gas two‑phase sealing in multiphase pumps.

To investigate the flow and heat transfer characteristics of liquid indium-tin-bismuth alloy within tubes，a systematic analysis was conducted on the effects of different tube types （including circular，elliptical，flattened，square，and triangular tubes） under the same equivalent diameter condition on temperature，velocity，and pressure distributions，as well as the influence of key thermal parameters such as Reynolds number and heat flux density on the heat transfer dynamics of the indium-tin-bismuth alloy.The results indicate that the square tube exhibits superior overall heat transfer performance compared to other tube types.When the inlet Reynolds number increased from 5 419 to 13 548，the heat transfer coefficient increased from 4 695.962 W/（m²⋅K） to 9 357.478 W/（m²⋅K）.When the wall heat flux density increased from 110 W/cm² to 130 W/cm²，the heat transfer coefficient increased from 4 695.962 W/（m²⋅K） to 5 541.235 W/（m²⋅K）.Both increasing the inlet Reynolds number and increasing the tube wall heat flux density significantly enhance the heat transfer efficiency between the liquid metal and the tube wall.This study provides a reference for the optimal design and application of thermal management systems utilizing liquid metals.

To address the issue of flow channel blockage caused by mineral particle sedimentation and backflow in a lifting pump after an emergency pump shutdown，CFD-DEM coupling method was used to numerically simulate internal solid‑liquid two‑phase flow during pump shutdown backflow conditions.The effects of changes in the number of impeller blades and diffuser blades on particle concentration distribution，particle backflow time，particle collision behavior，and backflow pass‑through rate were analyzed，and the reliability of the numerical simulation was verified through experiments.The results show an increase in the number of blades exacerbates particle accumulation and collisions in the first‑stage diffuser；optimizing blade number matching can significantly improve performance.When the number of impeller blades is 3 and the number of diffuser blades increases from 4 to 5，particle collision count decreases by 28.18%，and backflow pass‑through rate increases by 2.56%；when the number of diffuser blades is 5，increasing the number of impeller blades from 3 to 4 further reduces collision count by 12.36% and increases backflow pass‑through rate by 4.48%.The research results provide a theoretical basis for optimizing the design of lifting pumps.

To further reduce the oil concentration in the water outlet of the cyclone pre‑separation device and to lessen the load of subsequent treatment，a novel mixed‑flow hydrocyclone structure was proposed.Its performance was systematically investigated through numerical simulation and experimental validation methods.The results indicate that when the oil phase density is below 890 kg/m³，the oil viscosity is less than 75 mPa⋅s，and the inlet water cut ranges from 75% to 99%，the device can achieve performance indicators of a water separation efficiency greater than 50% and an oil concentration in the water outlet below 200 mg/L.When the inlet water cut is between 70% and 75%，the split ratio can be adjusted in the range of 0.55 to 0.65 with the oil concentration at the water cut below 400 mg/L.When the inlet water cut is not less than 75%，the split ratio can be adjusted from 0.4 to 0.6 with the oil concentration in the water outlet below 200 mg/L.The proposed mixed‑flow hydrocyclone demonstrates excellent separation performance under different water cut conditions.The research can provide an effective way for efficient pre‑separation of produced fluids from high‑water‑cut oil wells.

To address the severe erosion issue in common elbows for gas‑solid two‑phase flow，a pre‑helical pipe elbow was designed.The anti‑erosion structure of the helical pipe section was optimized using Fluent software in terms of twist angle，installation distance，and intermediate helical pipe section length，resulting in a pre‑helical pipe elbow with optimal anti‑erosion performance.The anti‑erosion effectiveness of this optimized structure was verified under varying medium flow velocities，mass flow rates，and time factors.The results show that the pre‑helical pipe elbow exhibits anti‑erosion effects only when the twist angle is between 90° and 600°，with an average improvement of 34.13% compared to the common elbow when the twist angle ranges from 210° to 420°.At twist angles of 390°，300°，and 330°，the maximum erosion rates of the pre‑helical pipe elbow are lower than those of the common elbow across the studied installation distances and intermediate helical pipe section lengths.Particularly when the installation distance is 0 mm and the intermediate helical pipe section length is 200~400 mm，the anti‑erosion effect is more significant.The optimized structural parameters are as follows：helical pipe section twist angle of 390°，installation distance of 0 mm，and intermediate helical pipe section length of 300 mm.Under these conditions，the pre‑helical pipe elbow achieves the best anti‑erosion performance，improving by 47.32% compared to the common elbow.Furthermore，although the maximum erosion rates of both this elbow and the common elbow increase with medium flow velocity，mass flow rate，and time，the maximum erosion rate of this elbow consistently remains lower than that of the common elbow，indicating that it maintains its anti‑erosion effectiveness at all times.The research results can provide a reference for the anti‑erosion structural design of elbows.

To address the issue of insufficient model accuracy for the R290 heat pump dryer dehumidification evaporator under complex thermal and humid conditions，a combined simulation and experimental approach was employed to study the flow heat transfer characteristics and performance optimization of the evaporator.Based on the unique two‑phase flow and heat transfer characteristics of R290，the general in‑tube two‑phase flow heat transfer model and pressure drop model were modified，and a distributed parameter model for the evaporator applicable to the large temperature‑humidity span conditions of dryers was constructed.A heat pump dryer experimental platform was built to validate the model accuracy across a wide range of humid air conditions （temperature 20~65 ℃，relative humidity 20%~95%）.The average errors for temperature and humidity predictions were 1.8 K and 5.1%，respectively.The results indicate that the heat transfer coefficient reaches its maximum，approximately 110 W/（m²·K），when the refrigerant quality inside the tube is around 0.4.There exists a limit to the dehumidification and heat transfer capacity of the evaporator；when the superheat exceeds 10~12 K，further increases in load lead to insignificant improvement （less than 4%） in heat exchanger performance.The findings provide a theoretical basis for optimizing the design and operation control of R290 heat pump dryer evaporators and offer certain engineering value for enhancing equipment energy efficiency and operational reliability.

To address the issues of single pumping performance diagnosis methods，limited regeneration capabilities，and insufficient testing accuracy in traditional Gifford-McMahon （GM） refrigerator cryopump test platforms，a high‑precision test platform was designed based on JB/T 11081—2011 standards.This platform integrates key data acquisition and display modules for temperature and vacuum，and innovatively introduces a thermal purge heating subsystem，while using a residual gas analyzer （RGA） to monitor real‑time pressure changes of the tested gas.Through theoretical calculations，simulation analysis，and experimental testing，the hydrogen pumping speed performance of the cryopump was validated.The results show that：the designed thermal purge device uses 100 ℃ nitrogen to purge the cryogenic surface，effectively meeting the regeneration heating requirements for flammable and explosive gases；during the test，cooling and vacuum performance remained stable without fluctuations；by collecting partial pressure changes before and after hydrogen injection，the measured average pumping speed was 4 291 L/s，with errors less than 10% compared to theoretical calculations （4 514 L/s） and simulation results （4 552 L/s），falling within the allowable error range，validating the rationality of the platform design.This platform can provide high‑precision testing methods for the performance optimization of domestic cryopumps.

To address the sediment wear issue in a centrifugal pump with adjustable guide vanes within a large‑scale water diversion project，a numerical prediction method based on the Euler-Lagrangian approach and a shape‑factor‑modified Oka model was established to study the internal flow field characteristics and wear patterns under low‑concentration sediment conditions.The results indicate that when the sediment concentration does not exceed 0.135 kg/m³，its influence on the internal flow field of the centrifugal pump is no more than 5%.Wear is primarily concentrated at the trailing edge of the blade suction side，the junction with the front shroud，and the leading edge of the adjustable guide vanes.The average wear intensity on the suction side is approximately 8.3 times that on the pressure side.Sediment concentration predominantly governs the linear regulation of wear intensity，while particle size primarily governs the wear distribution pattern：small particles cause severe wear at the trailing edge of the suction side，whereas large particles，due to inertial effects，shift wear towards the pressure side and the rear shroud.This study provides a theoretical basis for the wear‑resistant design and safe operation of centrifugal pumps with adjustable guide vanes.

To comprehensively understand the cooling effect of spray evaporation in double skin facade spray systems，a CFD two‑phase flow model for spray cooling double skin facade was established，and a discrete phase model （DPM） based on the Euler-Lagrangian method was employed to track the droplets.Through numerical simulation combined with experimental validation，the effects of parameters such as droplet injection velocity，spray flow rate，and number of nozzles on the cooling performance of the spray system were analyzed.The results show good consistency between the two，with the mean absolute percentage error for most temperature measurements within 15%，indicating that the DPM model can be used for simulation analysis of spray cooling in double skin facade.When the droplet injection velocity increased from 20 m/s to 80 m/s，the evaporative cooling efficiency of the spray system improved by 14.9%.Meanwhile，the spray flow rate also significantly influenced the cooling performance of the spray system.When the spray flow rate increased from 0.01 L/min to 0.09 L/min，the evaporative cooling efficiency of the system improved by 57.2%，the droplet evaporation rate increased by 2.9 μg/s，and the temperature distribution in the cavity became more uniform.The number of nozzles had a considerable impact on the cooling performance of the spray system.With three nozzles，the evaporative cooling efficiency and droplet evaporation rate of the system were 4.29 times and 2.6 times higher，respectively，compared to the single‑nozzle scenario.This research provides theoretical references for the optimal design of spray cooling systems and holds significant importance for improving the cooling performance of double skin facade.

To efficiently produce ice particles of targeted sizes for ice air jet applications，ice particles were generated using a direct contact cryo genic settling method.The effects of water flow rate （Q） and atomizing‑nozzle exit diameter （D） on the particle size distribution were systematically investigated. In addition，the atomization behavior and solidification heat transfer characteristics were analyzed using the Weber number （We），Stefan number （St），and Biot number （Bi）.The results show that the atomization process is jointly governed by D and Q.At a fixed flow rate，increasing D reduces the exit velocity and the diameter ratio （d/D），shifting the atomization mechanism from inertia‑dominated breakup to a surface‑tension‑dominated regime.At a fixed nozzle diameter，increasing Q drives the atomization mode from a transitional regime toward inertia‑dominated breakup.During solidification，sensible‑heat transfer is dominant.Internal conduc‑tion resistance is non‑negligible，while external convection remains an important limiting factor.Small ice particles，with large specific surface area and low internal temperature gradients，exhibit faster solidification，whereas large particles suffer from delayed core cooling，which significantly prolongs the phase‑change time.Ice particles produced using nozzles with D=2.5~3.5 mm exhibit a circularity close to 1，indicating favorable wear performance.The optimal operating parameters are identified as D=3.0 mm and Q=0.02 L/s. This study elucidates how process parameters govern ice‑particle size and heat‑transfer characteristics，providing theoretical support for the optimized design and engineering implementation of ice‑particle jet technologies