To address wear issues in a catalytic cracking unit cyclone separator，a gas‑solid two‑phase erosion mathematical model was established.Numerical simulations reproduced distribution characteristics of flow parameters including velocity fields and wear rates under typical operating conditions.Combined with field failure cases，erosion mechanisms were analyzed and control solutions proposed.Results show the swirler internal flow exhibits a dual‑layer rotational structure with outer downward flow and inner upward flow.Wall thinning primarily results from combined cutting wear and deformation wear.Silica particles continuously impact the swirler top at low angles，causing severe wear with a wear rate of 6.02×10^-9 kg/（m²·s）.During spiral downward movement，particles cause cutting wear on the cylinder wall.Reduced motion radius increases centrifugal force，leading to severe impact wear at the underflow orifice with a wear rate of 5.52×10^-9 kg/（m²·s）.Numerical results show high consistency with field cases.Wear‑resistant electrode overlay welding extends equipment life by 3~6 months，while alumina ceramic lining extends life by over 10 months.The established wear analysis method and control strategy can be applied to failure assessment and life optimization of cyclone separator wall thinning.

To enhance the efficiency and accuracy of three‑dimensional finite element model updating for nuclear power valve piping systems and ensure the reliability of analysis results，a three‑dimensional finite element model updating technique based on an inverse response surface model is proposed. First，a radial basis function‑backpropagation neural network is employed to fit an inverse response surface model that directly maps the resonant frequencies，anti‑resonant frequencies，and structural parameters of the valve piping system. Then，the measured frequencies are used as inputs to solve for the correction parameters，addressing challenges such as the difficulty in modeling vibration control equations for the three‑dimensional finite element model，the uncertainty of results from intelligent optimization algorithms，and the inefficiency of iterative updating processes. The proposed method is validated using an actual valve piping system. The results demonstrate that after measuring the actual dynamic characteristics，the trained inverse response surface model can complete the three‑dimensional model updating within seconds. The maximum error between the calculated frequencies of the updated model and the measured frequencies is reduced from 15.43% to 3.53%.The proposed method can be applied in engineering practice to update the three‑dimensional finite element model of nuclear power valve piping systems using measured frequencies.

To address the heat transfer deterioration caused by dust accumulation on outdoor heat exchangers of air‑source heat pumps，a visual dust removal test rig was constructed.Using mixed particles with diameters of 10 µm and 20 µm，dust removal tests were conducted on plain finned‑tube heat exchangers at different jet angles and wind speeds.Results show that under frontal horizontal jetting，when wind speed reaches 21 m/s，dust removal rate reaches 97%.Under reverse horizontal jetting at 28 m/s，dust removal rate is 40%.At 16 m/s frontal jetting speed，during the initial stage，dust removal rate increases with rising airflow angle，reaching a maximum of 94.7% at approximately 30° above horizontal.When airflow angle further increases，dust removal rate begins to decline.Dust removal mass ratio at 21 m/s frontal jetting speed also peaks around 30° at 92.9%.These findings provide important references for optimizing dust removal strategies of air‑source heat pump outdoor heat exchangers.

In order to investigate the leakage law of gas-liquid two‑phase flow in the first type leakage channel of single screw compressor under different conditions，the first type of leakage channel of a single screw compressor was simplified as a narrow channel，and the meshing clearance was the height.Using nitrogen as the gas phase medium and deionized water and glycerol solution as the liquid phase medium to study the influence low of pressure loss of gas-liquid two‑phase flow in narrow channels with the changes of gas‑liquid velocity，channel height and liquid viscosity.The results show that the pressure drop increases with the increase of gas‑liquid velocity，and the influence of liquid velocity on pressure drop is significantly greater than that of gas velocity.At a same gas‑liquid velocity，the pressure drop rapidly decreases with the increase of channel height.The pressure drop decreases the most when the height increases from 0.03 mm to 0.05 mm，and the pressure drop decreases less when the height increases from 0.05 mm to 0.08 mm.When the liquid phase velocity increases from 0.14 m/s to 0.28 m/s，the pressure drop of water，20% glycerol solution and 40% glycerol solution increase from 3.01 kPa，4.39 kPa and 8.61 kPa to 5.81 kPa，7.80 kPa and 15.5 kPa，respectively.A new correlation equation is fitted by modifying the Chisholm parameters of the split phase flow model，which can effectively predict the pressure drop in narrow channels with heights ranging from 0.01 mm to 0.08 mm，and a maximum deviation of no more than 25%.The research can provide theoretical reference for the design and manufacturing of single screw compressors.

In order to quantitatively explore the influence of cyclic oil injection quantity on the heat transfer performance of screw air compressors，experiments were conducted to study the effects of changing oil injection quantity and suction temperature on exhaust temperature，overall temperature difference，inlet and outlet oil temperature of oil coolers，logarithmic mean temperature difference and convective heat transfer coefficient under different operating conditions.At the same time，the curve of convective heat transfer coefficient and oil injection quantity was fitted using experimental data.The results show that the oil injection quantity and input power should be accurately matched under the rated exhaust pressure at full load.When the oil injection quantity decreases from 262 L/min to 134 L/min，the convective heat transfer coefficient of the oil cooler to decreases by 12.4%，the temperature difference of the lubricating oil will increase from 16.0 ℃ to 29.8 ℃，resulting in an 8.3% decrease in the logarithmic mean temperature difference of convective heat transfer under the original calculation conditions，increasing exhaust temperature.The research can provide theoretical guidance for solving the problem of high exhaust temperature in screw air compressor.

To further enhance aerodynamic efficiency and effectively reduce noise of air‑conditioning axial fans，a cross‑species multi‑element bionic design was applied to fan blades by combining the superior flight characteristics of seagull airfoils with the noise‑reducing non‑smooth functional structures of butterfly wing surfaces.First，CFD simulated internal flow characteristics and aerodynamic performance，with numerical model validity confirmed through experimental comparisons.Subsequently，large eddy simulation （LES） and FW-H acoustic analogy methods predicted noise levels of fans with composite bionic blades.Results demonstrate that cross‑species composite blades effectively reduce flow separation losses at blade tip clearances and decrease surface pressure fluctuations.Compared to the prototype fan at identical conditions （rotational speed 730 r/min），the composite blade fan shows：9.07% higher aerodynamic efficiency，126.4 m³/h increased airflow，70.2 W reduced power consumption，and 2.6 dB noise reduction.This study provides solution references for axial fan blade design and performance optimization.

Aiming at the problem of seal failure caused by thermal deformation of an aero‑engine fuel pump under extreme conditions such as high temperature and high speed，this study establishes a thermal-fluid-solid interaction model for an upstream pumping mechanical seal based on the mechanical seal structure of an afterburner fuel pump.Professional computational fluid dynamics software and a thermal-fluid-solid coupling platform are employed to calculate the stress and strain on the seal rings under extreme conditions.The influences of varying operating parameters—rotational speeds ranging from 20 000 to 40 000 r/min and pressure differences from 0.5 to 9 MPa—on the stress and strain of the mechanical seal rings are analyzed.Results indicate that when the liquid film thickness on the seal face is 2 μm，the spiral groove depth is 6 μm，the number of grooves is 12，and the spiral angle is 18°（serving as baseline parameters），both the dynamic and static seal rings experience measurable stress and strain as the rotational speed increases.Notably，the maximum stress and deformation of the dynamic ring exceed those of the static ring，with the maximum deformation difference between the two rings reaching 2.5 μm.As the sealing pressure difference increases，the stress and strain values of the seal rings increase linearly.However，the seal rings exhibit low sensitivity to pressure changes：for every 1 MPa increase in pressure difference，the strain increases by approximately 0.02 μm，and the maximum stress increases by approximately 0.3 MPa.Under all tested operating conditions，the seal rings generate corresponding stress and strain.Therefore，during the design and calculation processes，the impact of these stresses and strains on overall sealing performance must not be overlooked.The research results can provide valuable references for multi‑physical field coupling calculations of upstream pumping mechanical seals under extreme conditions.

In order to improve the heat transfer performance of the evaporator in the cold storage refrigeration system，a new type of plate evaporator was designed.The influence of refrigerant mass flow rate and air side velocity on the heat transfer characteristics of the plate evaporator was discussed by using the method of simulation combined with experiments，and an optimized structure with an intermediate channel was proposed.The heat transfer characteristics of the plate evaporator were studied when the inlet dryness of refrigerant R22 was 0.27，the temperature was -5 ℃，the saturation pressure at this temperature was 0.421 8 MPa，the mass flow rate was 0.017 kg/s，the air inlet temperature was 6 ℃，the relative humidity was 80%，and the flow rate was 3 m/s.The results show that in the design conditions，the cooling capacity in this design condition is 2.86 kW，the refrigerant side pressure drop is 1 150 Pa，and the air side pressure drop is 412 Pa.As the mass flow rate of refrigerant increases，the cooling capacity increases，but the growth rate slows down significantly after reaching 0.017 kg/s.The pressure drop on the refrigerant side also increases，and the growth rate gradually increases.As the inlet flow rate on the air side increases，the cooling capacity increases，but the growth rate slows down significantly after reaching 3 m/s.The pressure drop on the air side also increases，and the growth rate gradually increases.The refrigerant mass flow rate should match the air inlet conditions.Compared with the original structure，the plate evaporator with a middle connected structure has increased cooling capacity by more than 9.4%，increased refrigerant side pressure drop by 18.3%，and increased air side pressure drop by 20.2%.The intermediate connected structure can improve the heat transfer performance of the evaporator.The research results can provide reference for the study and design of evaporators in cold storage refrigeration systems.

To address the prevalent issues of high water content，associated gas，and difficult separation of small‑diameter bubbles in oilfields，a gas‑liquid‑inertial cyclone separator structure was designed based on inertial pre‑separation and centrifugal separation principles.This structure achieves bubble size reconstruction and pre‑separation by distributing bubbles of different sizes at distinct positions at the inlet，enabling smaller bubbles to migrate more easily toward the cyclone center，thereby improving separation efficiency.Numerical simulations comprehensively analyzed the pre‑separation effectiveness，flow field characteristics，and separation performance under various operating conditions.Results demonstrate that under conditions of inlet bubble size less than 50 μm，split ratio 13%，processing capacity 2.0 m³/h，and gas concentration 10%，maximum separation efficiency reaches 99.98%.The gas‑liquid‑inertial cyclone separator significantly enhances separation efficiency for micro‑bubbles，achieves efficient separation for bubbles of different sizes，and is suitable for complex industrial applications.

To address the low volumetric efficiency caused by significant leakage in small‑displacement submersible progressive cavity pumps，this study takes the GLB-20 pump as the research object.Using Ansys Fluent software，a fluid simulation model was constructed based on user‑defined functions（UDF） and dynamic mesh technology to simulate transient and steady‑state flow fields.The influence laws of structural parameters including eccentricity，stator lead，and clearance on flow velocity and leakage were investigated.Experimental validation of optimization results yielded the optimal design scheme.Results show the pump exhibits significant harmonic variation during operation，with flow pulsating twice per cycle matching the stator‑rotor lead ratio.Transient flow fields conform better to actual conditions than steady‑state fields.Clearance is the most critical factor affecting leakage and flow velocity：stator lead influences flow velocity more than eccentricity，while eccentricity affects leakage more than stator lead.Optimized parameters via Box-Behnken design （BBD） method are eccentricity 1.8 mm，stator lead 78 mm，clearance 0.3 mm.Leakage decreased by 12.7%，volumetric efficiency significantly improved，and flow stability enhanced.This research provides design basis for small‑displacement submersible progressive cavity pumps.