2020 Vol. 35, No. 12

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Review of aero-engine inlet swirl distortion research
CHENG Bangqin, WANG Jiale, FENG Luning
2020, 35(12): 2465-2481. doi: 10.13224/j.cnki.jasp.2020.12.001
Abstract PDF(4495KB) icon702 icon548
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In order to improve and develop the research system of inlet swirl distortion of aero-engine, the generation and source of inlet swirl distortion were reviewed, and the methods of simulating swirl distortion at home and abroad were summarized. The influences of swirl distortion of different types and structures on the performance and stability of compressors and aero-engines were summarized. The existing problems and difficulties in the current study of swirl distortion were analyzed synthetically, and the development trend of swirl distortion was discussed. Following suggestions are given: a variable swirl distortion generator should be developed. It is necessary to investigate the influence mechanism of swirl distortion on engine performance to lay a foundation for extending stable working range of engine effectively. Many ways should be used to extend stable working range of compressor/engine under the condition of inlet swirl. A unified evaluation index of swirl distortion should be established and incorporated into the integrated distortion index system. The design method of small distortion inlet should be explored.
Design and optimization of columniform distributed ejector for low speed wind tunnel inlet test
WU Chaojun, XU Binbin, ZHANG Weizhuo
2020, 35(12): 2482-2488. doi: 10.13224/j.cnki.jasp.2020.12.002
Abstract PDF(2496KB) icon475 icon205
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In order to meet the urgent requirement of large flow simulation in low speed wind tunnel for engine inlet test, a design scheme of columniform distributed ejector for 4 m-scale low speed wind tunnel was proposed. The internal flow filed of ejector was simulated by ANSYS-CFX software using the finite volume method. The design parameters were optimized, including the ejecting area rate, discrete distribution of nozzles and the design point total pressure and Mach numbers of nozzle outlet. The improved design of ejector met the limited condition in wind tunnel and the acquirement of large mass flow, and solved the contradiction of small size and large mass flow. The experiment in FL-14 wind tunnel indicated that the max absorbing mass flow rate of improved ejector can reach 9.07 kg/s, fulfilling the large mass flow needs of inlet test in 4 m-scale low speed wind tunnel.
Unsteady pressure boost micro-scale Laval nozzle flow characteristics
XU Xiao, WANG Yuanding, ZHANG Jun
2020, 35(12): 2489-2504. doi: 10.13224/j.cnki.jasp.2020.12.003
Abstract PDF(8862KB) icon326 icon225
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Targeting the unsteady pressure boost of the micro-scale jet when the spacecraft motion state was switched, the micro-scale Laval nozzle flow in the stepped pressure boost and linear pressure boost modes was used to simulate by direct simulation of Monte Carlo (DSMC) method, and comparative analysis of the flow characteristics in the process of change was done. Results showed that step-type pressure boost could cause a large amplitude peak-valley fluctuation in the flow characteristics, while the flow characteristics under linear pressure boost showed the characteristics of linear change; the viscous force played an important role in the unsteady pressure boost of micro-scale jet, especially in the flow field from the expansion section of the throat to the outlet; the total impulse, mass flow rate produced by the micro-scale jet and the impulse provided by unit quality working medium during the stepped pressure boost process was 59.5%, 74.7% higher, and 8.6% lower than the characteristics in linear pressure boost process, meanwhile, the volatility of the stepped pressure boost process was more obvious than the linear pressure boost process. It can be seen that the stepped pressure boost mode is suitable for system that requires large thrust to change the motion state and has sufficient propellant, and the linear pressure boost has obvious advantages when the system needs to be fine-tuned precisely or the propellant is required to produce higher efficiency. These research conclusions provide an effective reference for the design and optimization of micro-scale nozzles under different system conditions.
Control calculation of helicopter rotor tip vortex in forward flight using steady air mass injection
YE Zhou, ZHAN Fengjiang, XU Guohua
2020, 35(12): 2505-2513. doi: 10.13224/j.cnki.jasp.2020.12.004
Abstract PDF(4707KB) icon326 icon320
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A high-accuracy numerical method was established to simulate the rotor flowfield of rotor tip vortex with tip air mass injection (TAMI) control in forward flight. In the existing method, the finite volume method was used for spatial discretization. The upwind Roe scheme with a fifth-order WENO (weighted essentially non-oscillatory) scheme was employed to calculate convective fluxes on control faces. A dual-time method was utilized in time marching and the high-efficiency implicit LU-SGS (lower upper symmetric Gauss-Seidal) scheme was applied to every pseudo time step. A surface boundary condition which may effectively simulate the effect of TAMI was introduced into this method. The moving overset grid method of refining the blade grid and background grid pertinently was adopted to simulate the blade flapping and rotating motions. Based on the presented method, rotor tip vortex with TAMI control in forward flight was calculated. It demonstrated that there existed obvious difference between the tip vortex induced at the front side of rotor disk and that induced at the rear side. The core strength of tip vortex induced at the front side was smaller than that at the rear side. Tip vortex induced at the front side of the rotor disk cannot be weakened. However, tip vortex induced at the rear side can be effectively weakened by the steady TAMI.
Dynamic characteristics of thermocouple in gas medium
YANG Zhaoxin, ZENG Xing, ZHANG Wenqing
2020, 35(12): 2514-2520. doi: 10.13224/j.cnki.jasp.2020.12.005
Abstract PDF(2313KB) icon306 icon199
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In order to estimate the dynamic characteristics of the thermocouples and fulfill the matching requirement of dynamic characteristics estimation with the gas medium, the dynamic characterization research of the thermocouples with the gas medium was studied. Based on the improvement of structure and function of traditional shock tube, dynamic calibration equipment for the gas temperature was designed, the traceability method of standard signal of dynamic temperature calibration was analyzed, the dynamic model of thermocouple was established, and precise description and experimental verification was realized. The result of dynamic calibration experiment showed that the dynamic calibration equipment for the gas temperature based on traditional shock tube transformation could generate standard temperature signal featuring wide frequency coverage and steady step amplitude. The dynamic calibration requirement of the conventional thermocouples can basically be fulfilled by the generated standard temperature signal; the thermocouple dynamic model and the order can be estimated very accurately with the adopted dynamic modelling method. With the verified results of the experiment, the correlation coefficient between the response signal of the established thermocouple dynamic model and the testing response signal could achieve 0.996 7, which can generally satisfy the requirement of dynamic characterization estimation of thermocouple in the engineering applications.
Development of force measuring device for an aircraft thrust vectoring test
MIAO Lei, LI Yaohua, LI Jianqiang
2020, 35(12): 2521-2531. doi: 10.13224/j.cnki.jasp.2020.12.006
Abstract PDF(2472KB) icon362 icon192
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For aircraft thrust vectoring test, two six-component strain-gauge balances and an air-line bridge were applied to respectively measure the performance of the whole aircraft and nozzle at the same time. Based on the finite element software, the strains of two balances and the interference of the air-line bridge on balance were analyzed. The results showed that the interference values of air-line bridge to the force components were better than 5%, and the interference values to the moment components (except for rolling moment) were better than 15%, which reached the design index. By calibration, the formulas of single balance and balance with air-line bridge (pressurized and non-pressurized states) were obtained. The calibration results showed that the comprehensive loading error of each component of the two balances was better than 0.3%, the comprehensive loading error of each component of balance with air-line bridge (pressurized and non-presswrized states) was better than 0.5%, and the interference values of air-line bridge to balance were consistent with the results of finite element analysis. Theoretical analysis and test results show that the development of balances and air-line bridge has reached the predetermined goal and its accuracy is high, which meets the requirements of the thrust vectoring wind tunnel test.
引用格式：王庆宇,刘琪麟,赖焕新.高亚声速喷流近场的流-声关联［J］.航空动力学报,2020,35(12):2532-2542.WANG Qingyu,LIU Qilin,LAI Huanxin.Flow-acoustics correlations in near-fields of high subsonic jet［J］.Journal of Aerospace Power,2020,35(12):2532-2542.Flow-acoustics correlations in near-fields of high subsonic jet
WANG Qingyu, LIU Qilin, LAI Huanxin
2020, 35(12): 2532-2542. doi: 10.13224/j.cnki.jasp.2020.12.007
Abstract PDF(5464KB) icon475 icon100
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Large eddy simulation was carried out to predict the flow and acoustic near fields of a subsonic jet at Mach number of 0.9. The calculation was validated by available DNS and experimental data. Then the correlations between turbulent fluctuations along the center line and shear layer of the jet and the monitored sound pressure signals were analyzed. Furthermore, attentions were also paid to temperature signals on center line so as to unveil their contribution to sound. Results showed that the correlation coefficient peaks near the end of the potential core, indicating that the turbulence signals here contributed the most to the near-field sound pressure signal,and the flow in this area also had high intermittent and convective velocity. The near field sound pressure was also strongly correlated with the fluctuations of the temperature on the center line. But for the gradient of the temperature, only the radial component was intensely correlated with the sound pressure, while the correlation between axial component of the temperature gradient and the sound signal was relatively weak，indicated that the axial temperature gradient contributed little to the near field sound pressure under the simulated temperature ratio.
Numerical simulation of flow and heat transfer characteristics in passage with triangular pyramids
BAO Feng, HOU Chang, JIANG Yurong
2020, 35(12): 2543-2552. doi: 10.13224/j.cnki.jasp.2020.12.008
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Numerical simulation was performed for the internal cooling passage of turbine blades with triangular pyramids, and the focus was put on the flow and heat transfer characteristics in the cooling passage, with respect to the differences between cases of windward and leeward conditions, aligned and stagger arrangements, different horizontal columns and different streamwise spacing ratios. Results revealed that the decrease of pressure loss and improvement of heat transfer efficiency attributed to the longitudinal vortex generated by the triangular pyramids. The case of leeward condition with aligned arrangement had the highest comprehensive heat transfer efficiency, which was 20%-30% higher than other cases; while in this case, the most suitable number of horizontal columns was 5, and the streamwise spacing ratio was 4-6.
Lagrangian simulation method of droplet collection efficiency for complex configuration
REN Jinghao, YI Xian, WANG Qiang
2020, 35(12): 2553-2561. doi: 10.13224/j.cnki.jasp.2020.12.009
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A robust and efficient algorithm was developed for calculating the droplet collection efficiency and overcoming the non-universal defect in the Lagrangian method. A point-locating scheme based on a non-plane intersection determination algorithm was used to achieve the fast localization of droplets in polyhedron mesh. Using mesh adaptive refine techniques and curve projection algorithm, the difficulty of calculating collection efficiency on complex configuration was avoided. This step effectively reduced the complexity of the algorithm. The analysis results discretely distributing in the spatial configuration was interpolated to the model surface by radial basis function. Some cases valuated the improved algorithm. The testing report showed that the deviation of the calculating results using the proposed method from the experimental data was not more than 15% and the necessary trajectories for calculation significantly decreased compared with the traditional model. It shows that the this method has high engineering practice value and popularization sense.
Use two-dimensional Bayesian method to solve inverse heat conduction problem for rotating disc cavity
YANG Yang, CAO Nan, CHEN Hang
2020, 35(12): 2562-2572. doi: 10.13224/j.cnki.jasp.2020.12.010
Abstract PDF(3620KB) icon352 icon169
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In order to study the heat transfer characteristics of compressor rotating disc cavity, and calculate the surface heat transfer coefficient on rotating disc accurately, a two-dimensional Bayesian method was introduced. Using prior distribution to optimize temperature measurement error, this method agreed well with the two-dimensional characteristics of rotating disc. Using simulation data with noise to verify the feasibility of method, the results showed that the average error without temperature measurement error was 3.2% and the average error with temperature measurement error was 10.6%.The error source was analyzed too. By comparing with existing experimental data, results showed that the method was more suitable for calculating surface heat transfer coefficient when the windward and leeward surfaces had a large difference in heat transfer. The average relative error was 9.6%, meeting actual engineering accuracy requirements. By changing the number of temperature measurement points on disc surface, it was found that the increase in measurement points could improve calculation accuracy, and the statistical sampling theory was used to analyze the phenomenon. It was found that when the acceptable error was 10%, the number of measuring points required was reasonable.
Experiment on characteristics of velocity and temperature fields of rotating boundary layer
LI Gangfu, LI Haiwang, YOU Ruquan
2020, 35(12): 2573-2582. doi: 10.13224/j.cnki.jasp.2020.12.011
Abstract PDF(3642KB) icon359 icon149
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For the turbine rotor blade internal cooling technology, TR-PIV (time resolved particle image velocimetry) and hot wire technology were used to measure the velocity and temperature field of the boundary layer in the rotating channel under wall heating conditions. The results showed that when the rotation number was greater than 0.48, backflow occurred near the leading side, and an explanation was given from the force analysis. The backflow zone generally appeared downstream the flow field at a higher density ratio and a higher rotation number. The backflow effects can be used to achieve the purpose of enhancing the heat transfer of the leading side. The change laws of the dimensionless temperature profiles, temperature fluctuation and Nusselt number under different rotation conditions were obtained. The temperature field distribution inside the turbulent boundary layer produced a strong asymmetry under the rotation effect, generating a certain deviation compared with the standard law under static conditions.
Experiment on spray characteristics of self-pressurized injector for aircraft piston engines,
LOU Huangqiang, WEI Minxiang, LIU Rui
2020, 35(12): 2583-2592. doi: 10.13224/j.cnki.jasp.2020.12.012
Abstract PDF(4955KB) icon319 icon164
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For the better application of the self-pressurized injector on aircraft piston engines, the spray characteristics of a self-pressurized injector was experimentally studied in a constant-volume vessel. Spray characteristics of RP-3 aviation kerosene under different ambient pressure, fuel temperature and ambient temperature were studied using visualization technology combining Matlab image processing program. Result showed that, the surface waves and fuel strings can be observed obviously under the ambient pressure of 0.1 MPa. With the ambient pressure increasing from 0.1 MPa to 0.8 MPa, the typical hollow cone spray was transformed into a hollow cone spray with large scale vortexes. The maximum spray penetration reduced by 45%, and the maximum spray area reduced by 55.3%, respectively. The increase of fuel temperature promotes spray evaporation to facilitate cold start. The spray penetration, area and cone angle were all minimum when the fuel temperature was 50 ℃. At the ambient pressure of 0.1 MPa, the spray penetration and area increased at first and then decreased with the increase of ambient temperature. The maximum spray penetration reached 67.3 mm at ambient temperature of 60 ℃, the maximum spray area reached 915.5 mm2 at ambient temperature of 50 ℃, respectively. The spray cone angle decreased with the increasing of ambient temperature, reaching the minimum value of 9.2° at ambient temperature of 90 ℃.
Flame structure in supersonic combustion chamber based on 500 Hz OH-PLIF technology,
YE Jiawei, ZHANG Shunping, YU Xin
2020, 35(12): 2593-2601. doi: 10.13224/j.cnki.jasp.2020.12.013
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500 Hz high-speed OH-PLIF technology was used for the research of the flame structure in supersonic combustion chamber, which was characterized by short time-lag and high turbulence in cavity chamber. Combining the pressure of the wall surface, the ignition, stabilization and extinguishing of the flame were studied. The results showed that ignition occurred when the hydrogen equivalents were 0.1 and 0.3. PLIF camera got the image in 2 ms under the spark. A detonation combustion existed in the cavity of the equivalent ratio of 0.1, and the flame was slower to reach stable state in the cavity (about 65 ms). In the process of stabilization of the flame, the equivalent 0.3 was in an incomplete combustion state, the burning area was closer to the wall, the burning position and nuclear position of the fire were greatly changed at the equivalent 0.3. At the equivalent of 0.1, the flame was transmitted from the middle of the cavity to the front edge of the cavity with a process of a briefly increased flame. Flame extinguished at the front edge of the cavity. However the equivalent 0.3 was slightly weaker, which was eventually extinguished between the front edge of the cavity and the position of hydrogen injection.
Aero-engine unbalanced fault location identification method based on deep learning
CHEN Guo, YANG Mohan, YU Pingchao
2020, 35(12): 2602-2615. doi: 10.13224/j.cnki.jasp.2020.12.014
Abstract PDF(4297KB) icon417 icon207
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For the problem of aero-engine unbalanced fault location diagnosis based on casing test points, a method of aero-engine unbalanced fault location diagnosis based on deep convolution neural network was presented. The coupling dynamic model of a typical dual-rotor aero-engine was established, and the numerical integration method was used to realize the numerical simulation of unbalanced fault. Four unbalanced fault positions were selected from the high and low pressure rotors of the compressor end to the turbine end as the diagnostic object. A large number of unbalanced fault samples obtained by simulation were used to train the deep convolution neural network, and the excellent feature learning ability of the deep convolution neural network was used to realize the identification of different positions of the aeroengine unbalanced fault. The numerical experimental results fully showed the accuracy of the method to identify the unbalanced fault locations of aero-engine reached to 95%.
Solution method of rotor finite element model with nonlinear support
HAN Bingbing, DING Qian
2020, 35(12): 2616-2625. doi: 10.13224/j.cnki.jasp.2020.12.015
Abstract PDF(3000KB) icon314 icon154
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The dynamic behavior of a flexible rotor system with nonlinear support was studied by the numerical method of a model and the solution combining the finite element model with nonlinear supports. The finite element method (FEM) was used to build the model of the rotating shaft and the rotary table, and the matrix was used for combination; the discrete element method was used to model the support (including: rolling bearing and squeeze film damper (SFD)), which specifically consists of four elements: bearing inner ring, outer ring, SFD inner ring and supporting cage. The finite element part and the discrete element part were connected by the nodes at the shaft end, and the displacement at the shaft end was transmitted to the nonlinear support. The nonlinear force and the nonlinear support calculated by the displacement at the support acted on the finite element rotor part at the shaft end in turn. In order to solve the coupling problem of the finite element rotor and the nonlinear support, a comprehensive iterative method was proposed to overcome the limitation of the traditional finite element method for solving the implicit nonlinear support at the shaft end. Because the Timoshenko beam element was used to model the rotating shaft, the gyroscopic moment and the flexibility of the shaft can be considered, which can better reflect the real effect of nonlinear support on the vibration.In the 20 shaft finite elements rotor model, the nonlinear response was more reflected in the 1 and 21 nodes closed to the nonlinear supports, and the nodes near the shaft end in the response spectrum can reflect two times and three times the flexible vibration frequency of the rolling bearing.
JIA Shengxi, ZHENG Longxi, LI Shengyuan, MEI Qing
2020, 35(12): 2626-2634. doi: 10.13224/j.cnki.jasp.2020.12.016
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Given that the dynamic characteristics of rotor system must be considered during design of squeeze film damper (SFD), a coupling design method of rotor system and SFD was proposed, and the detailed design process was shown. Computational fluid dynamics (CFD) simulation, oil film pressure measurement and vibration reduction experiment were carried out. The results showed that the proposed design method was effective. The amplitude of the two disks on the rotor system decreased by 46% and 39%, respectively, after using SFD. The effects of unbalance, support stiffness, oil supply pressure and oil temperature on the damping effect of SFD were also studied. The results show that the effect of oil supply pressure and oil temperature is not significant compared with that of unbalance and support stiffness. It is important to pay attention to the unbalance and support stiffness when designing SFD.
Three-dimensional imaging analysis of tension-compression fatigue damage in viscoelastic damper
ZHANG Baoshuang, AO Bo, DING Yang
2020, 35(12): 2635-2641. doi: 10.13224/j.cnki.jasp.2020.12.017
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Three-dimensional observation of the damper was performed by micro-CT (micro computed tomography), and the imaging resolution was 91.89 μm. The voids and cracking defects of the rubber layer were successfully extracted through three-dimensional segmentation, and quantitative analysis of defects’ geometric parameters such as diameter and total volume was performed. In order to improve the imaging resolution, local high-resolution micro-CT imaging and 3D visualization analysis of single void defects were performed to obtain the information of single void morphology. The results showed that the main defects of viscoelastic damper mainly included debonding, void and cracking, the maximum void diameter of the upper and lower rubber layers was 13.12 mm and 12.21 mm, respectively. It was found that cracking existed at the ends of the upper and lower sections, the ring-shaped crack body extended upward to the surface of the rubber layer and downward to the outer wall of the aluminum alloy inner tube. The three-dimensional imaging resolution of local micro-CT was 20.85 μm. The experimental results showed that the surface morphology of a single void had wrinkles and pits, but no micro-cracks were found. Digital radiography(DR) experiment results show that it is feasible to detect the debonding and void defects of rubber layer in viscoelastic damper by X-ray tangential radiography.
Flow control mechanism of diffuser cascade corner-suction surface profiling design
LI Xiangjun, DONG Jiezhong, CUI Yiqiang
2020, 35(12): 2642-2653. doi: 10.13224/j.cnki.jasp.2020.12.018
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Through numerical simulation, the optimal profiling under the design point and near stall point were compared, allowing for analyzing the flow field structure and compressor performance changes and exploring the mechanism of the two kinds of optimized profiling to improve the compressor performance. The optimization results showed that the suction surface of the optimal profiling under the design point was sunken, which reduced obviously the thickness of the boundary layer on the suction surface; and blend blade and end wall was close to the trailing edge, which reduced the low energy fluid in the corner zone and produced transfer under the impact of the pressure gradient. For the optimal profiling under the near stall point, the blend blade and end wall was close to the leading edge and the suction surface was convex, which promoted the fluid adhesion in advance when fluid entered the leading edge, and the leading edge separation area decreased sharply or even disappeared. The optimal profiling adapted to all working conditions can be constructed based on the two profiling controlling mechanisms and structure features, yielding extremely positive effect on many working conditions.
Effect of sensor angle deviation on fan/compressor azimuthal mode recognition,
CHAI Pengfei, ZHANG Zhiwei, SUN Zonghan
2020, 35(12): 2654-2663. doi: 10.13224/j.cnki.jasp.2020.12.019
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Based on the arbitrary angle compressive sensing (CS) method, the influence of sensor installation angle deviation on the fan/compressor azimuthal mode recognition was analyzed, and an adaptive angle optimization program was designed to correct the reconstruction error. The influence of angle deviation and number of sensors on the results of azimuthal mode reconstruction was investigated by numerical experiments. When the angle deviation level was 2.5%, the average reconstruction error was more than 10%. If the reconstruction error was basically unchanged, and the number of sensors increased from 7 to 25, the angle deviation level can only be expanded to 4%. The niching micro genetic algorithm was used for adaptive angle optimization. Under 20 dB signal-to-noise ratio, the angle deviation level can be expanded from 2.5% to 10% through adaptive angle optimization, which reduced the accuracy requirements for sensor installation. The reconstructed amplitude of the main azimuthal acoustic mode at the first three-order blade passing frequency of a cooling fan was optimized. It was shown that the adaptive angle optimization method can effectively improve the reliability of fan/compressor azimuthal mode reconstruction based on CS.
,Friction torque characteristic of ball-roller combined turntable bearing,
ZHANG Zhanli, ZHANG Kaizhe, WANG Hengdi
2020, 35(12): 2664-2672. doi: 10.13224/j.cnki.jasp.2020.12.020
Abstract PDF(2417KB) icon399 icon136
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In order to study the friction torque characteristics of the ball-roller combined turntable bearing, a mechanical model of the bearing was established, and solved by the Newton-Raphson method. The mechanism of bearing friction torque was analyzed. The friction torque calculation model was established, and the model was tested and verified by using a testing machine. The effect of different structural parameters on bearing friction torque was studied. The results showed that the established model can predict the bearing friction torque well. The bearing friction torque was positively related to the axial load, overturning torque and bearing speed; the reduced initial axial clearance can significantly reduce the bearing friction torque; there was an optimal value for the number of steel balls to minimize bearing friction torque. There was a reasonable interval for the radius of groove curvature to optimize the overall performance of the bearing; appropriately reducing the mass of the cage can effectively reduce the friction torque of the bearing. The research results provide a theoretical basis for the optimal design of the ball-roller combined turntable bearing.
Experiment methods of transmission efficiency for helicopter main gearbox
WANG Di, XIA Haichun, NI De
2020, 35(12): 2673-2680. doi: 10.13224/j.cnki.jasp.2020.12.021
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Based on the principle of direct and indirect testing methods of transmission efficiency, the transmission efficiency experiment of the helicopter main gearbox was carried out for the first time in China. The results showed that transmission efficiency was positively related to input torque and oil temperature, and negatively related to the input speed. The transmission efficiency changed obviously under low torque. The rate of change of transmission efficiency with rotating speed was obviously smaller than that with torque. The indirect testing method results of transmission efficiency were greater than direct testing method. With the increase of input torque, the relative difference between indirect and direct testing methods of transmission efficiency decreased gradually, while it was not obvious with the rotating speed. The results of error analysis showed that the limit error of indirect testing method was less than that of direct testing method, and the maximum error of direct and indirect testing method was 1.28% and 0.72%, respectively.
Effect of weld reinforcement methods on bearing performance of large diameter tank bottom
HU Zhenggen, ZHAN Lihua, DONG Manhong
2020, 35(12): 2681-2688. doi: 10.13224/j.cnki.jasp.2020.12.022
Abstract PDF(4087KB) icon223 icon127
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Based on the finite element method, the influence of weld reinforcement methods (double symmetry reinforcement, inner surface reinforcement，outside surface reinforcement) on internal pressure bearing capacity of typical 10 m class diameter tank bottom was studied. The two-dimensional symmetric plane model was used for numerical calculation, and the effects of the real boundary conditions of the tube segment and the short shell and the weld on the bearing capacity were considered. The nonlinear numerical analysis model considering the plasticity of the material was constructed to accurately obtain the meridional stress on the inner and outer surfaces of tank bottom. Results showed that the weld area of the top and melon flap was a weak area of tank bottom. Under operating pressure, meridional stress difference between inner and outside surfaces of double symmetric reinforcement was smallest, and none of them presented plasticity. Meridional stress difference of single-side reinforcement was much larger than double symmetric reinforcement, and local plasticity occurred. Compared with inner surface reinforcement, the maximum and minimum meridional stress differences of outside surface reinforcement increased by 9.7% and 27.2%, and all of them led to uncoordinated deformation. Under design pressure, inner and outside surface meridional stress of tank bottom had local plasticity, and material plasticity had certain coordination effect on the inner and outside surface meridional stress difference, which can significantly alleviate the additional bending moment caused by the inner and outside surface stress difference. Double symmetric reinforcement was better than outside surface reinforcement, and inner surface reinforcement was better than outside surface reinforcement. The single-side reinforcement was easy to generate additional bending moment, which was not conducive to the uniform bearing and deformation coordination of tank bottom. The research results provide a guidance to the optimization design of the bottom structure of large diameter storage tank.

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