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Chinese Journal of Aeronautics 2024年第6期37卷 20-37页

作者： Zhiyu LI Kaiyuan ZHANG Zhigang LI Jun LI institute of turbomachinery Xi’an Jiaotong UniversityXi’an 710049China

The mid-passage gap is an inevitable structure in a vane passage due to turbine vanes being manufactured *** coolant from this gap is able to prevent hot mainstream ingression and provide cooling protection for the endwall.A novel idea of enlarging the endwall’s coverage area and reducing the endwall’s thermal load by applying the mid-passage gap with variable surface angles is carried out in this *** endwall’s aerothermal and film cooling performances under four mid-passage gap modes at three typical mass flow ratio conditions are numerically *** indicate that under the traditional mid-passage mode,the coolant flows into the mainstream with a perpendicular incidence angle and can’t stick to the ***,cooling failure occurs,and the endwall’s thermal load is badly *** film cooling level at the suction-side endwall is improved when applying the mid-passage gap of a 45surface angle due to the secondary vortex being *** addition,when applying the mid-passage gap of a 135surface angle,the horseshoe vortex is pushed away,and the coverage area at the pressure-side endwall is enlarged *** best film cooling performance is achieved when the upstream surface angle is 135and the downstream surface angle is 45due to the adiabatic film cooling effectiveness being increased at both the pressure-and suction-side *** the mass flow ratio is 1.5%,the coverage area is enlarged by 43%,and the area-averaged adiabatic film cooling effectiveness is increased by 37%,when compared with those under the traditional mid-passage mode.

关键词： Film cooling Heat transfer Surface angle Mid-passagegap Turbinevane endwall

A Method for the Determination of Turbulence Intensity by Means of a Fast Response Pressure Probe and its Application in a LP Turbine

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Journal of thermal Science 2012年第1期21卷 21-31页

作者： Davide Lengani Berardo Paradiso Andreas Marn Inst. f. thermal turbomachinery and machine dynamics Graz University of Technology

This paper describes the measurements and the post-processing procedure adopted for the determination of the turbulence intensity in a low pressure turbine (LPT) by means of a single sensor fast response aerodynamic pressure probe. The rig was designed in cooperation with MTU Aero Engines and considerable efforts were put into the adjustment of all relevant model parameters. Blade count ratio, airfoil aspect ratio, reduced massflow, reduced speed, inlet turbulence intensity and Reynolds numbers were chosen to reproduce the full scale LP turbine. Measurements were performed adopting a phase-locked acquisition technique in order to provide the time resolved flow field downstream of the turbine rotor. The total pressure random fluctuations are obtained by selectively filtering, in the frequency domain, the deterministic unsteadiness due to the rotor blades and coherent structures. The turbulence intensity is derived from the inverse Fourier transform and the correlations between total pressure and velocity fluctuations. The determination of the turbulence intensity allows the discussion of the interaction processes between the stator and rotor for engine-representative operating conditions of the turbine.

关键词： Turbulence fast response aerodynamic pressure probe low pressure turbine.

Heat Recuperation for the Self-Condensing CO_(2)Transcritical Power Cycle

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Journal of thermal Science 2024年第5期33卷 1630-1641页

作者： PAN Lisheng SHI Weixiu SUN Yin SUN Yiwei WEI Xiaolin State Key Laboratory of High-temperature Gas dynamics Institute of MechanicsChinese Academy of SciencesBeijing 100190China School of Environment and Energy Engineering Beijing University of Civil Engineering and ArchitectureBeijing 100044China

The supercritical CO_(2)Brayton cycle has potential to be used in electricity generation occasions with its advantages of high efficiency and compact *** on a so-called self-condensing CO_(2)transcritical power cycle,a model was established and four different layouts of heat recuperation process were analyzed,a without-recuperation cycle,a post-recuperation cycle,a pre-recuperation cycle and a re-recuperation *** results showed that the internal normal cycle's share of the whole cycle increases with increasing the cooling pressure and decreasing the final cooled *** load in the supercritical heater decreases with increasing the cooling *** perspective of performance,the re-recuperation cycle and the pre-recuperation cycle have similar thermal efficiency which is much higher than other two *** thermal efficiency and net power output have a maximum value with the cooling pressure,except in the condition with the final cooled temperature of 31℃.Considering both the complexity and the economy,the pre-recuperation cycle is more applicable than the other *** 35℃of the final cooled temperature,the thermal efficiency of the pre-recuperation cycle reaches the peak 0.34 with the cooling pressure of 8.4 MPa and the maximum net power output is 2355.24 kW at 8.2 MPa of the cooling pressure.

关键词： CO_(2)transcritical power cycle heat recuperation process self-condensing

Three-Dimensional Convection in an Inclined Porous Layer Subjected to a Vertical Temperature Gradient

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Fluid dynamics & Materials Processing 2024年第9期20卷 1957-1970页

作者： Ivan Shubenkov Tatyana Lyubimova Evgeny Sadilov Computational Fluid dynamics Laboratory Institute of Continuous Media Mechanics UB RASPerm614068Russia Theoretical Physics Department Perm State UniversityPerm614990Russia

In this paper,we study the onset and development of three-dimensional convection in a tilted porous layer saturated with a *** layer is subjected to a gravitational field and a strictly vertical temperature ***,problems of thermal convection in tilted porous media saturated with a liquid are studied by assuming constant different temperatures at the boundaries of the layer,which prevent these systems from supporting conductive(non-convective)*** boundary conditions considered in the present work allow a conductive state and are representative of typical geological *** an earlier work,we carried out a linear stability analysis of the conductive *** was shown that at any layer tilt angles,the most dangerous type of disturbances are longitudinal ***,a non-zero velocity component exists in *** the present work,threedimensional non-linear convection regimes are *** original three-dimensional problem is reduced to two-dimensional one with an analytical expression for the velocity z-component v_(z)=v_(z)(x,y).It is shown that the critical Rayleigh number values obtained through numerical solutions of the obtained 2D problem by a finite difference method for different layer inclination angles,are in a good agreement with those predicted by the linear *** number of convective rolls realized in nonlinear calculations also fits the linear theory predictions for a given cavity *** carried out at low supercriticalities show that a direct bifurcation takes *** increasing supercriticality,no transitions to other convective regimes are *** situation studied in this problem can be observed in oil-bearing rock formations under the influence of a geothermal temperature gradient,where the ensuing fluid convection can affect the distribution of oil throughout the layer.

关键词： thermal convection inclined layer porous media vertical temperature gradient

Boundary slip and lubrication mechanisms of organic friction modifiers with effect of surface moisture

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Friction 2024年第7期12卷 1483-1498页

作者： Xiaobin YI Haiyu XU Ge JIN Yang LU Biqiang CHEN Shaofeng XU Junqin SHI Xiaoli FAN State Key Laboratory of Solidification Processing Center of Advanced Lubrication and Seal MaterialsNorthwestern Polytechnical UniversityXi’an 710072China Xi’an thermal Power Research institute Co. Ltd.Xi’an 710054China NingboTech University Ningbo 315000China

Surface moisture or humidity impacting the lubrication property is a ubiquitous phenomenon in tribological systems,which is demonstrated by a combination of molecular dynamics(MD)simulation and experiment for the organic friction modifier(OFM)-containing *** stearic acid and poly-α-olefin 4cSt(PAO4)were chosen as the OFM and base oil molecules,*** physical adsorption indicates that on the moist surface water molecules are preferentially adsorbed on friction surface,and even make OFM adsorption film thoroughly leave surface and mix with base *** shear process,the adsorption of water film and desorption OFM film are further enhanced,particularly under higher shear *** simulated friction coefficient(that is proportional to shear rate)increases firstly and then decreases with thickening water film,in good agreement with experiments,while the slip length shows a contrary *** wear increases with humidity due to tribochemistry revealing the continuous formation and removal of Si–O–Si *** tribological discrepancy of OFM-containing lubricant in dry and humid conditions is attributed to the slip plane’s transformation from the interface between OFM adsorption film and lubricant bulk to the interface between adsorbed water *** work provides a new thought to understand the boundary lubrication and failure of lubricant in humid environments,likely water is not always harmful in oil lubrication systems.

关键词： organic friction modifier(OFM) boundary lubrication boundary slip surface moisture

Reduced Spring Precipitation Bias and Associated Physical Causes over South China in FGOALS-f3 Climate Models:Experiments with the Horizontal Resolutions

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Journal of Meteorological Research 2024年第4期38卷 784-804页

作者： Peng ZI Yimin LIU Jiandong LI Ruowen YANG Bian HE Qing BAO Department of Atmospheric Science Yunnan UniversityKunming 650504 State Key Laboratory of Numerical Modeling for Atmospheric Sciences and Geophysical Fluid dynamics(LASG) Institute of Atmospheric PhysicsChinese Academy of SciencesBeijing 100029

Considerable spring precipitation occurs over South China(SC),a region that is adjacent to large-scale Asian topography and *** reasonable simulation is crucial for improving regional climate *** study investigates spring precipitation biases over SC and their possible causes in atmosphere-only and coupled Flexible Global Ocean–Atmosphere–Land System finite-volume version 3(FGOALS-f3) models with different horizontal *** performance of spring precipitation simulation over SC varies across different FGOALS-f3 model versions,with the best reproducibility in the high-resolution coupled model(25 km).In the low-resolution atmosphere-only model(100–125 km),the precipitation dry bias over SC is closely linked to overestimated surface sensible forcing over the eastern Tibetan Plateau(TP),which weakens the subtropical anticyclone over the western Pacific(SAWP) through regional circulation *** contrast,the high-resolution atmosphere-only model further amplifies surface thermal forcing in the Asian continents,causing intensified land–sea thermal contrast between the Southeast Asian continents and western Pacific,enhanced southerly winds and SAWP,and increased water vapor transport into ***,the reduced middle–high level cold bias over 10°–30°N in the high-resolution atmosphere-only model intensifies the East Asian westerly jet and ascent over SC,leading to enhanced spring precipitation *** high-resolution coupled model simulation not only reduces sea surface cold bias over the Bay of Bengal,thus intensifying the Indian–Burma trough and strengthening low-level water vapor transport into SC,but also enhances ascent over *** a result,the high-resolution coupled model better reproduces the magnitude and pattern of spring precipitation over SC than its atmosphere-only *** with low-resolution models,the domain-mean spring precipitation dry bias decreases by 11.2% over SC in the high-resolution atmosphere-only mod

关键词： South China spring precipitation high resolution Flexible Global Ocean–Atmosphere–Land System finite-volume version 3(FGOALS-f3)models simulation

Influence of ion size on the charge storage mechanism of MXenes:a combination of experimental and computational

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Waste Disposal and Sustainable Energy 2024年第2期6卷 163-171页

作者： Huiwen Wan Rui Wang Huiyang Fan Hongbo Gao Yucheng Chen Zhu Liu State Key Laboratory of Clean Energy Utilization Institute for Thermal Power EngineeringCollege of Energy EngineeringZhejiang UniversityHangzhou 310027China China North Vehicle Research institute No.4 HuaishulingFengtai DistrictBeijingChina ZJU-Hangzhou Global Scientific and Technological Innovation Center Zhejiang UniversityHangzhou 311215China

MXene nanomaterials have attracted great interest as the electrode of ***,its energy storage mecha-nisms in organic electrolytes are still *** work investigated the size effect of cations(i.e.,Lit,Nat,K^(+),and EMIM^(+))on the capacitive behaviors of MXene-based *** experimental results demonstrate that the specific capacitance increases obviously with decreasing cation size(i.e.,from 43 F g^(-1)(EMIM^(+))to 129 F g^(-1)(Li^(+))at 2 mV s^(-1)).Density-functional theory calculation reveals a correlation between cation size and ion-electrode surface interaction,sup-porting experimental observations of the capacitive-dominant *** dynamics simulations reveal that the ionic solvation structure and desolvation degree of intercalated cations as a function of solvation size,providing dynamic insights into the experimentally observed specific capacitance *** comprehensive experimental and computational study provides valuable insights into the intricate solvation effects governing the charge storage *** finding of ion dynamics,solvation structure,and desolvation may contribute to guide the design and optimization of appropriate ions/electrolytes combinations for MXene-based supercapacitors.

关键词： MXene Cations Molecular dynamics simulation Density-functional theory calculation Supercapacitors

Impact of Clocking on the Aero-Thermodynamics of a Second Stator tested in a One and a Half Stage HP Turbine

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Journal of thermal Science 2008年第2期17卷 97-110页

作者： N.Billiard G.Paniagua R.Dénos turbomachinery and Propulsion Department von Karman institute for Fluid dynamics

This paper focuses on the experimental investigation of the time-averaged and time-accurate aero- thermodynamics of a second stator tested in a 1.5 stage high-pressure turbine. The effect of clocking on aerodynamic and heat transfer are investigated. Tests are performed under engine representative conditions in the VKI compression tube CT3. The test program includes four different clocking positions, i.e. relative pitch-wise positions between the fh-st and the second stator. Probes located upstream and downstream of the second stator provide the thermodynamic conditions of the flow field. On the second stator airfoil, measurements are taken around the blade profile at 15, 50 and 85% span with pressure sensors and thin-film gauges. Both time-averaged and time-resolved aspects of the flow field are addressed. Regarding the time-averaged results, clocking effects are mainly observed within the leading edge region of the second stator, the largest effects being observed at 15% span. The surface static pressure distribution is changed locally, hence affecting the overall airfoil performance. For one clocking position, the thermal load of the airfoil is noticeably reduced. Pressure fluctuations are attributed to the passage of the up- stream transonic rotor and its associated pressure gradients. The pattern of these fluctuations changes noticeably as a function of docking. The time-resolved variations of heat flux and static pressure are analyzed together showing that the major effect is due to a potential interaction. The time-resolved pressure distribution integrated along the second stator surface yields the unsteady forces on the vane. The magnitude of the unsteady force is very dependent on the clocking position.

关键词： transonic flow turbines stator clocking forces heat transfer.

Spatially resolved investigation of flame particle interaction in a two dimensional model packed bed

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Particuology 2024年第2期85卷 167-185页

作者： Mohammadhassan Khodsiani Reza Namdar Fathollah Varnik Frank Beyrau Benoit Fond institute of Fluid dynamics and Thermodynamics Universitaetsplatz 2Magdeburg39106Saxony-AnhaltGermany Interdisciplinary Centre for Advanced Materials Simulation(ICAMS) Ruhr-University BochumBochum44801Germany ONERA The French Aerospace Lab Department of AerodynamicsAeroelasticity and Acoustics(DAAA)Paris-Saclay UniversityMeudon92190France

This study investigates the interaction between a premixed methane-air flame and particles inside a model packed *** opacity of the spherical packed beds to visible light poses a major barrier to the implementation of highly resolved optical diagnostics,so that no detailed experimental data were so far available for the validation of numerical ***,a two-dimensional cylindrical packed bed design is set up,which enables direct line-of-sight optical measurements without loss of spatial reso-lution over the fluid region between the *** this study,the case of cold metallic cylindrical particles(T=377 K)relevant to start-up of a reactor is investigated using internal particle cooling,which also allows cylinder specific heat transfer rate measurements by differential temperature measurements on the coolant *** two dimensional assumption is first verified by measuring the inflow ve-locity and cylinder temperature profile along the *** imaging is then per-formed using a telecentric lens to observe the position and geometry of the two-dimensional flame front with respect to the surrounding cylinders without loss of ***,the cylinder-specific flame to cylinder heat transfer rates and cylinder surface temperature are *** the flame is closely surrounded by the three cooled cylinders,intense heat transfer is observed in this region corresponding to 25±2.5%of the flame thermal *** were stabilised at different positions depending on inflow velocity and equivalence ratio,and a direct correlation between flame to cylinder stand-off distance and the heat transfer rate normalised to the flame thermal power was found for both top and side ***,sidewall quenching distances to the curved cylinder surfaces were evaluated,and seem to be influenced by the presence of a warm recirculation zone behind the *** investigation provides fully resolved flame front position and heat tra

关键词： Packed beds Flame-particle interaction Optical diagnostics Sidewall quenching

Conditional Generative Adversarial Networks for modelling fuel sprays

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能源与人工智能(英文) 2023年第2期12卷 62-75页

作者： Cihan Ates Farhad Karwan Max Okraschevski Rainer Koch Hans-Jörg Bauer Karlsruhe institute of Technology(KIT) Institute of Thermal TurbomachineryGermany Karlsruhe institute of Technology(KIT) Machine Intelligence in Energy SystemsGermany

In this study, the probabilistic, data driven nature of the generative adversarial neural networks (GANs)was utilized to conduct virtual spray simulations for conditions relevant to aero engine combustors. Themodel consists of two sub-modules: (i) an autoencoder converting the variable length droplet trajectories intofixed length, lower dimensional representations and (ii) a Wasserstein GAN that learns to mimic the latentrepresentations of the evaporating droplets along their lifetime. The GAN module was also conditioned withthe injection location and the diameters of the droplets to increase the generalizability of the whole *** training data was provided from highly resolved 3D, transient Eulerian–Lagrangian, large eddy simulationsconducted with OpenFOAM. Neural network models were created and trained within the open source machinelearning framework of PyTorch. Predictive capabilities of the proposed method was discussed with respect tospray statistics and evaporation dynamics. Results show that conditioned GAN models offer a great potentialas low order model approximations with high computational efficiency. Nonetheless, the capabilities of theautoencoder module to preserve local dependencies should be improved to realize this potential. For the currentcase study, the custom model architecture was capable of conducting the simulation in the order of secondsafter a day of training, which had taken one week on HPC with the conventional CFD approach for the samenumber of droplets (200,000 trajectories).

关键词： Generative Adversarial Networks Generative learning Fuel injection Aero engines Multivariate time series