The experimental research on the dynamic response of aero-engine rotor under sudden impact load was carried out by using high-speed motor drive on the vibration table. Rotor dynamic response tests under different characteristic speeds, load sizes, impact directions, and pulse widths were completed, revealing the general rules of rotor dynamic response under sudden impact loads. The results show that the dynamic response of the rotor increases instantly and then returns to a stable state when under instantaneous impact, and it increases with the increase of the sudden impact load. Besides, the vertical dynamic response of the rotor is greater than the horizontal dynamic response, and the vertical response of the same measurement section is 4% to 46.15% greater than the horizontal response under various operating conditions. In addition, the dynamic response of the rotor under axial foundation impact is greater than that under vertical foundation impact. Within a certain range, as the pulse width of the impact load increases from 6 ms to 11 ms, the dynamic response of the rotor decreases by 2.5%~10%. The study provides a reference for the vibration response analysis of aero-engine rotors under sudden impact loads and the structural safety design of aero-engine, which has important engineering application value.

With the development of global trade, buoyancy-lifting hybrid airship is an important choice for global long-distance and large-load transportation, it has gradually become a research hotspot at home and abroad. In order to improve the transportation efficiency of buoyancy-lifting hybrid airship, its layout and parameter sensitivity were studied. Discussions were conducted on the hull layout and tail wing layout, and several types of hull and tail wing layouts with high lift to drag ratios were proposed. At the same time, a sensitivity analysis was conducted on the impact of design parameters on aerodynamic characteristics. The results indicate that the width of the hull has the most significant impact on the lift coefficient, drag coefficient, and maximum lift to drag ratio of airships. Its relative sensitivity coefficient is nearly ten times that of the longitudinal position and inclination angle of the tail wing. The inclination angle of the tail wing has the strongest impact on the torque coefficient of the airship, and its relative sensitivity coefficient is more than twice the width of the hull.

With its advantages in cooling efficiency and cost, the cold channel closed system is more and more used in the construction of new data centers. However, the closed channel system will turn the originally open channels between data center cabinets into narrow spaces with restricted ventilation. When the main combustibles in the data center catch fire, the accumulated hot smoke and gas in the closed channel cannot be timely discharged, seriously threatening the safety of data center equipment and personnel. At present, there is a paucity of experimental data and theoretical basis for the fire hazard of cables commonly used in data centres. Pyrosim software was used to establish a full-size physical model of the data center room in the cold closed channel, and fire dynamics simulator(FDS) software was used to establish a full-size fire model to simulate different fire source locations, so as to analyze the changes of fire parameters such as smoke spread rate, visibility and temperature distribution. The results show that when a fire occurs under the floor (maximum heat release rate reaches 2 000 kW), the smoke would fill the whole machine room more quickly due to the influence of the special air conditioning airflow and floor than the cabinet fire. The visibility at the safety exit measuring point reached 0 m, 60 s earlier than the fire at the inside of the cabinet. At the same time, affected by the air conditioning airflow and perforated tiles, the temperature at the inside of the cabinet quickly reaches the critical value where the fire hazard is much greater. The results could provide important theoretical support for the fire protection system design of the cold channel of closed data center.

Process production safety monitoring is the main technical method for safety risk control and accident prevention, and data is a significant basis for safety control and decision-making. In the existing security monitoring network, there are many sensor nodes and large amounts of data, which cause heavy channel load in the wireless sensor network. This often leads to issues such as data latency and loss, which affects the timeliness and accuracy of safety control decisions. Therefore, the security risk factors of typical process production scenarios were focused on. Based on this, the sensor deployment plan and wireless sensor network data transmission architecture were clarified, a security monitoring data flow scheduling method based on superior-subordinate server was proposed, and the data stream congestion index and abnormal data packet frequency index were used as the main indicators of data flow performance evaluation. Subsequently, the chemical polymerization reactor were taken as an engineering scenario, the performance improvement was examined after the subordinate server was initiated to share the data flow for the superior server. Through the comprehensive study of channel load balancing, the method of superior-subordinate server is benefit to ensure the effectiveness of orderly transmission of safety monitoring data and risk control.

In order to investigate the potential causative factors and mechanisms of accidents in the flight transit security system, and to further ensure the safety of civil aviation operation, based on the system theory and the gray correlation theory, and combining with the actual situation of the flight transit security operation process, the safety problems in the system were transformed into the control and feedback problems, and the safety control and feedback structure was mapped out. Using complex network theory to transform accident causation and its logical relationship, a directed weighted accident causation network model was constructed, the overall characteristics of the network and the connection of each node from different perspectives were quantitatively analyzed, such as the node degree, the network diameter and the average path length, etc., and then 16 important accident causation factors affecting the flight transit security system were selected. Through grey correlation analysis, the influence degree of each cause factor on the accident was judged, and the key cause factors that need to be prevented and controlled were finally determined. The results show that the personnel factor dominates the accidents in the flight crossing security system, and its sub-factors, such as speeding, insufficient number of personnel, error of towing personnel and illegal entry of personnel into the control area, are the key causal factors leading to the accidents.

CO₂ foam fracturing can reduce reservoir damage and contribute to the stimulation of unconventional oil and gas reservoirs. However, there needs to be more quantitative methods to evaluate the influence of the CO₂-H₂O ratio of foam fracturing fluid on the conductivity, and the optimization of foam fracturing fluid system is insufficient. To select the CO₂ foam fracturing fluid system suitable for the conglomerate reservoir in the Mahu Basin, proppant embedment experiments were carried out with the treatment of foam fluid with different CO₂-H₂O ratios at simulated reservoir conditions, and each interval of embedment depth was obtained. A conductivity model considering the heterogeneous proppant embedment was established to calculate the effects of different foam fluids on improving the conductivity and analyze its mechanism. The results show that using CO₂ to replace part of the water-based fracturing fluid can reduce the degree of proppant embedment. With the increase of the CO₂-H₂O ratio, the effect of improving the conductivity weakens and reaches the upper limit gradually, increasing by about 12% compared with that of water-based fracturing fluid. When the ratio is 7∶3, the conductivity of samples with low clay content (<20%) increases to the upper limit. However, the conductivity of samples with high clay mineral content (≥20%) is more sensitive to the influence of the CO₂-H₂O ratio, and the upper limit is lower. CO₂ foam fracturing fluid can improve the hydrological capacity of the propped fracture-formation system. The research results can reference the CO₂-H₂O ratio optimization of the CO₂ foam fracturing fluid system.

In the process of oilfield development, the formation of emulsion between crude oil and water is quite common, which increases the difficulty of crude oil treatment. The composition of crude oil, especially the precipitation of paraffin wax, has significant influence on the stability of the emulsion. From the unique perspective that the oil composition affects the phase change and then further determines the emulsion stability, a systematic study was carried out with the methods of emulsion stability test, oil-water interfacial characteristic test, wax precipitation test, asphaltene dispersion stability test, and microscopic observation. It is observed that increasing the amount of liquid paraffin in the solvents leads to a change in the form of wax crystals from fine particles to larger agglomerated wax crystals, and the asphaltenes dispersion stability decreases along with it. Test temperature can significantly affect emulsion stability. At 30 ℃, increasing the percentage of liquid paraffin reduces the interfacial tension, increases the interfacial dilatational modulus, and enhances the structure of the interfacial film. This contributes to the formation of small droplets and improves emulsion stability to a certain extent. At 15 ℃, by contrast, increasing the liquid paraffin content promotes the development of a more structured wax crystals network, which significantly enhances emulsion stability by binding water droplets. Additionally, it is also found that a wax crystal interfacial film could be formed at the surface of the emulsified drops, which improves further the interfacial film strength and emulsion stability. Based on the above findings, an influencing mechanism model is presented concerning the synergistic stabilization of model oil emulsion containing asphaltene and paraffin wax.

The problem of inaccurate evaluation of the clamping performance of the spiral angle type slip will be effectively overcome, which is caused by the unclear contact characteristics between the slip and the pipe string. The forces acting on the interaction between slip and columns were analyzed by the theoretical method. A full-scale finite element model of the interaction between the slip, pipe column, and slip seat was established using the numerical simulation method. The mises stress and contact stress distribution patterns of the slip and pipe column under different axial loads and friction coefficients were studied. The mises stress and contact stress gradually decreases from the bottom to the top in the axial direction. They are an imperfect symmetric distribution in the circumferential direction. And there are stress concentration locations. The slip is subjected to higher mises stress and lower contact stress than the pipe column. As the axial load increases, the mises and contact stress increase. As the friction coefficient increases, the mises and contact stress decrease. In design and practical use, emphasis should be placed on components and locations with high-stress levels. Under high load conditions, increasing the friction coefficient by changing the material and shape of the slip teeth is recommended. Further the clamping performance of the slip under high load conditions is improved. It also prevents damage to the pipe column caused by excessive clamping force. The research results can provide theoretical guidance for the design of slips and the evaluation of clamping performance.

In order to effectively reduce the erosion and wear rate of ordinary elbows and extend their service life. A stomach-type elbow was proposed, based on the theory of gas-solid two-phase flow, the Fluent software was used on the stomach-type elbow to numerically simulate and analyze fluid erosion characteristics. The analysis results show that the second circular cross-section position less than 7.5°, greater than 25.0° less than 40.0° of the gastric bend has an erosion-resistant effect, in which the second circular cross-section position of 35.0° of the gastric bend erosion-resistant effect is the best, compared with the ordinary elbow erosion-resistant performance increase by 9.88%. The flow rate increases from 8 m/s to 28 m/s, and the maximum erosion rate of the gastric bend and ordinary elbow at 35.0°, 37.5°, 30.0° and 32.5° increases by 26.08 times on average. The particle diameter increases from 45 mm to 120 mm, and the maximum erosion rate increases by 1.71 times. The mass flow rate increases from 0.02 kg/s to 0.12 kg/s, and the maximum erosion rate increases by 7.35 times. Mass flow rate increases from 0.02 kg/s to 0.12 kg/s, the maximum erosion rate increases by 7.35 times. Regardless of the flow rate, particle diameter, mass flow rate, 35.0°, 37.5°, 30.0°, 32.5° of the maximum erosion rate of the gastric bend is always less than the maximum erosion rate of the ordinary elbow, that is, all have the effect of anti-erosion, of which 35.0° of the gastric bend on the whole has the best anti-erosion effect. The elbow can effectively reduce the rate of erosion and wear to extend the service life of the pipeline, but also for the elbow of the anti-erosion structure design and optimization to provide a new design scheme.

To further improve the transmission performance of non-circular gear pair, a new helical non-circular gear with point contact was proposed based on the meshing principle of gears. Mathematical model of helical non-circular gear with point contact was constructed. Geometric kinematic relationships between the pitch curve and tooth profile curve for helical non-circular gear with point contact under spatial coordinate system were deduced. Tooth surface design of the gear was completed. Three-dimensional solid models of helical non-circular gear pair with point contact was established by using the convert-tooth shape method. The dynamic simulation model of helical non-circular gear with point contact was established. The dynamic meshing forces of the new gear pair and general involute non-circular gear pair under the same conditions were analyzed. Meshing characteristics of helical non-circular gear with point contact under different working conditions were also obtained. The tooth surface contact state and contact stress of point contact non-circular gear and involute non-circular gear under the same parameter and working condition were compared and analyzed. Research results provide an important theoretical support and reference value for the design and application of non-circular gear pair.