最新刊期
卷 53 ， 期 9 ， 2019
- 摘要：As a particle-based method, moving particle semi-implicit method(MPS)is widely used for analy-ing unsteady flow with free surface.However, a certain degree of pressure fluctuation may occur when solving a specific problem.In this paper, the influence of the shape feature of the kernel function curve on the stability of pressure solution in MPS is analy-ed.An exponential polynomial kernel function is constructed, which is verified by a typical static pressure example(hydrostatic pressure problem)and a dynamic pressure example(liquid sloshing problem).Simulation is conducted and the results are compared with the theoretical solution or experimental results.It is found that the improved kernel function can effectively suppress the pressure oscillation in the simulation process.Studies have shown that the shape features of the ratio of the kernel function to the corresponding particle number density can truly reflect the interaction between particles and play a vital role in the analysis o关键词：moving particle semi-implicit method;kernel function;pressure oscillation;hydrostatic pressure;liquid sloshing428|6|4更新时间：2025-07-09
- 摘要：Effects of squealer winglet structure on the heat transfer characteristics and aerodynamic performance of turbine rotor blade tip are numerically investigated using Reynolds-averaged Navier-Stokes(RANS)equation and k- turbulence model.Numerical results of the heat transfer coefficients distribution at rotor blade tip agree well with the experimental data and the reliabilty of this numerical method is validated.The numerical results show that the average heat transfer coefficients of rotor blade tip with squealer winglet structure on the pressure side or suction side, as well as on both pressure and suction sides, are decreased by 12.2%, 17.1% and 19.8%, respectively, in comparison with those of traditional squealer tip.Squealer winglet structure on the pressure and suction sides of the rotor blade tip can decrease the tip leakage flow and weaken the influence of corner and scraping vortexes near the pressure side.This flow behavior also decreases the heat transfer coefficient of rotor关键词：turbine rotor blade;squealer tip;squealer winglet structure;aerodynamic performance;numerical simulation504|6|5更新时间：2025-07-09
- 摘要：A prediction model of bristle pack deformation in consideration of the leakage flow aerodynamic force, the frictional force between bristles, and the interaction between bristle pack and front or backing plate was presented.The three-dimensional Reynolds-averaged Navier-Stokes(RANS)equations based on non-linear Darcian porous medium model and combined with finite element analysis contact model were applied to analy-e the effects of three different backing plate structures on the leakage flow, tip force and heat transfer characteristics of the brush seal.The numerical results of leakage flow rate of brush seal with typical backing plate structure agree well with the experimental data, which verifies the reliability of this numerical method.The results show that the influences of the backing plate with annular groove on the leakage flow and pressure distribution of brush seal are small compared with typical backing plate structure.The axial aerodynamic force acting on the bristle pack in关键词：brush seal;backing plate structure;bristle pack deformation;leakage flow aerodynamic force;heat transfer300|6|8更新时间：2025-07-09
- 摘要：In this investigation, the effects of rim seal diversion configurations on the aerodynamic and film cooling performances of turbine stage were analy-ed with axial rim seal as the research object.Firstly, hyperbola, ellipse and circle rim seal diversion configurations were designed based on the conventional axial rim seal configuration.Three-dimensional Reynolds-averaged Navier-Stokes(RANS)equations, coupled with a fully-developed shear stress transport(SST)turbulent model from Ansys-CFX, were utili-ed to evaluate the influence of rim seal diversion configurations on the interaction of the hub leakage flow with the mainstream in the turbine stage.The results show that all the three diversion configurations of hyperbola, ellipse and circle rim seals could improve the turbine efficiency compared with axial seal.The circle rim seal provides the best aerodynamic and film cooling performances of turbine stage.Compared with axial seal, the circle rim seal could improve the turbine efficiency446|6|5更新时间：2025-07-09
- 摘要：When a centrifugal compressor operates near the stall point, the positive incidence angle at the diffuser inlet makes flow separation appear near the diffuser suction side, leading to compressor stall and surge.The leading edge structure of diffuser has an important effect on the compressor's performance and flow field.To extend stable operating range of centrifugal compressors, the flow separations within the diffuser passage near stall point need to be suppressed.In this research, numerical simulations were performed for a highly loaded centrifugal compressor to investigate the design method of slotted diffuser and discuss the influences of slot length and depth on the stage performance and stall margin.The results indicate that the compressor performance is deteriorated with the increase of slot length and depth, although the stall margin is expanded.In conclusion, the slot depth should not exceed 9% of the diffuser vane height, and the optimal slot length should not be more than 6%关键词：centrifugal compressor;slotted diffuser;numerical simulation;stall margin382|6|3更新时间：2025-07-09
- 摘要：The high-cycle fatigue of mistuned blade disks caused by vibration locali-ation has adverse effects on safety of the blades.A real blisk structure contains many details, so if FEM is used, the number of nodes in the mesh is so large that the modal computation efficiency is low.In order to solve this problem, a perturbed order-reduction method is proposed in this paper.Firstly, the blade disk's stiffness and mass matrixes are divided into two components: the tuned component and the mistuned component.Then, the mistuned component of the original structure is transformed into the corresponding change in the order-reduced structure by using coordinate order-reduction transformation relationship in the fixed interface modal synthesis method.The coordinated modal information is repeatedly used by the perturbation method.The solution of mistuned blade disk modal is transformed into the product of tuning matrix and mistuning matrix, and the natural frequencies and modals of blade disk under mi关键词：mistuned blade disk;modal analysis;perturbation order-reduction244|6|0更新时间：2025-07-09
- 摘要：To study the structure and evolution of the surface wave in a resonant mixing vessel and the influence of parameter excitation thereon, the surface characteristics of free liquid in a mixing container were explored by using the perturbation expansion method to solve the surface wave governing equation.Based on the theory of small amplitude wave, the model equation was solved by perturbation method.The surface wave modes in the mixing container with a liquid level of 7 cm were numerically analy-ed with the driving frequencies of 36 and 52 H-.The surface wave(8,4)mode and surface wave(7,6)mode diagrams and their crest and trough diagrams were obtained.The variation of surface wave patterns with time in a certain period of time under(7,6)mode was investigated, and the water wave ripples were qualitatively described.The spatiotemporal chaos under(7,6)mode was also analy-ed.Results show that the surface wave pattern may become complex with the increase of driving frequency.Before and after关键词：perturbation expansion;resonant mixing container;surface wave;spatiotemporal chaos323|6|0更新时间：2025-07-09
- 摘要：Optimi-ation schemes of synchronous and asynchronous intake timing combined with turbocharger matching are designed to improve the low-speed performance of a natural gas engine modified from a turbocharged gasoline engine.Then bench test and numerical simulation are used to investigate the effects of different intake optimi-ation schemes on the performance of the natural gas engine.It is found that the boost pressure and the intake flow rate of the natural gas engine at low speeds increase obviously by matching a turbocharger smaller than that of the original gasoline engine.The backflow at the end of intake stroke is reduced at low speeds when adopting the synchronous intake timing scheme with a smaller intake duration angle and delayed closing angle, which results in an obvious increase in the intake flow rate at low speeds.When adopting asynchronous intake timing scheme, the further decreased intake duration angle of one intake valve may lead to a further increase of 46% in the inta关键词：natural gas engine;asynchronous intake timing;turbocharger matching;low-speed torque299|6|0更新时间：2025-07-09
- 摘要：Aiming at the problem that transition resistance and measurement error affect the accuracy of fault location in transmission line, a novel method of fault location for transmission line based on two-level back propagation(BP)neural network is proposed.Analy-ing the change of the two-terminal electrical quantity with transition resistance, the regional characteristics of the change regularity of the two-level electrical quantity are determined, and the research idea of precise positioning in different regions is introduced.The first level network is used to fuse the two-terminal electrical quantity, and fault scenarios are divided into low-resistance fault and high-resistance fault.Low-resistance fault location network and high-resistance fault location network in the second level network are used to fuse the two-terminal electrical quantity of low-resistance fault and high-resistance fault respectively, and the accurate fault location is evaluated.Then the training method is improved,关键词：transmission line;fault location;two-level back propagation neural network;transition resistance;measurement error259|6|2更新时间：2025-07-09
- 摘要：The accuracy of wind measurement by the traditional time difference method is directly affected by the measurement accuracy of the ultrasonic propagation time.A three-dimensional wind parameter measurement method based on spatial ultrasonic sensor array and beamforming algorithm is proposed, in which a new structure of spatial ultrasonic sensor array with one transmitter and multiple receivers is adopted and the beamforming algorithm is used for spatial filtering to enhance the desired signal, suppress interference and improve the accuracy of wind measurement.Simulation shows that the success rate of wind measurement can reach almost 100% when the signal-to-noise ratio is 5 dB, and the higher the signal-to-noise ratio, the higher the success rate of wind measurement and the smaller the root mean square error.A hardware experimental platform is constructed to verify the proposed wind measurement method.It is shown that in wind tunnel the wind speed measured is 6.363 7 m/s, which is only关键词：three-dimensional wind parameter measurement;ultrasonic sensor array;beamforming algorithm;measurement accuracy333|8|4更新时间：2025-07-09
- 摘要：To improve the cooling effect of traditional circular impinging jet, screw hole is used to replace the round hole.The complex flow and heat transfer performance of the swirling impinging jet with an inclined screw hole are studied by numerical simulation.The influencing factors include jet inclination angle(-=45- - 90-), impingement distance(H/d=2,4,6), and Reynolds number(Re=6 000 - 24 000).The results show that the inclination angle and impact distance have great influences on the si-e, shape and position of vortices in the jet space.Under inclined screw-hole conditions, the impingement cooling effect of rotating jet is better than that of circular-hole jet, but when the inclination angle is equal to 45-, the convective heat transfer effect of the swirling jet impinging on target surface may deteriorate obviously.When Re=6 000, -=60- and the impingement distances H/d are 2, 4 and 6, the Nusselt number at the center of swirling jet target surface is 139.9%, 107.2% and 27.3% high关键词：swirling impinging jet;inclination angle;heat transfer;numerical simulation251|6|1更新时间：2025-07-09
- 摘要：Due to the low accuracy of the existing models for calculating the mixture viscosity of CO2 expanded systems, the experimental viscosity data of 7 different CO2 expanded liquids were collected from the literatures, the studied mixtures include CO2/n-decane, CO2/n-tetradecane, CO2/n-octane, CO2/methanol, CO2/ethanol, CO2/1-propanol, and CO2/acetone.Based on these viscosity data, an improved Eyring-NRTL viscosity model was established.The binary interaction parameter in the model was considered as a function of effective molar mass of the mixture, and the corresponding coefficients were obtained based on the regression of the literature data.Results show that the average relative deviation between the calculated viscosity values and the data from literatures is lower than 3% for CO2/n-dencane system(except at the temperature of 310.93 K)and 4% for other CO2 expanded li关键词：Eyring-NRTL viscosity model;CO2 expanded system;gas-liquid mixture228|6|1更新时间：2025-07-09
- 摘要：The film cooling effectiveness of the turbine blade with compound-angled fan-shaped holes was measured by the pressure sensitive paint technique.The wake's Strouhal number was varied from 0 to 0.36 and three mass flux ratios were determined.Results show that the compound-angled holes can enhance the lateral spreading of coolant, and the injection has a wider coverage area without wakes.The increase of the mass flux ratio causes an increase in the film cooling effectiveness over the leading edge and most area of the pressure surface with compound-angled holes, but a decrease on the suction surface.The increase of mass flux ratio also reduces the area near the tip on the suction side, where the film coverage is insufficient under wake influence, and causes an increase in the film cooling effectiveness over the leading edge, the pressure surface and the suction surface near the trailing edge, but decreases this effectiveness on the mid-chord region of the suction surface.The wake causes a关键词：compound-angled fan-shaped hole;wake;film cooling effectiveness;pressure sensitive paint;turbine blade273|6|5更新时间：2025-07-09
- 摘要：To shorten the processing period during containment test in nuclear power plant, a feasibility study was carried out.Firstly, the volatility test results of the chemicals used during containment test were analy-ed, and 25 combustible substances were screened out.Then, the lower flammability limits of the 25 substances were tested at the temperature of 60 - or a little above their flash points, under the pressures of 100, 310 and 520 kPa, respectively.The results indicate that the lower flammability limits of the liquids with low flash points are almost the same at different initial pressures.For the liquids with high flash points, there appears a phenomenon that their vapors cannot be ignited due to partial liquefaction of the combustible vapors at high pressures, which is favourable to reduction of flaming risk during containment test.Finally, for the 11 substances which will become nonflammable when the pressure reaches a certain value, a method was proposed to estimate the maximum关键词：nuclear power plant;containment test;lower flammability limit;flash point263|6|5更新时间：2025-07-09
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