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Experimental Study on Heat Transfer and Flow Resistance in Improved Latticework Cooling Channels

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Journal of Thermal Science 2013年第3期22卷 250-256页

作者： Hongwu Deng Kai Wang jianqin zhu Wenyan Pan National Key Laboratory of Science and Technology on Aero-Engine Aero-Thermodynamics School of Jet Propulsion Beihang University Institute of Engineering Thermophysics Chinese Academy of Science

Characteristics of heat transfer and flow resistance of the latticework (vortex) cooling channel with ribs truncated at their two ends were theoretically and experimentally studied compared with regular and smooth channels of the same configuration. The results showed: the heat transfer efficiency of the latticework channel with two slots was better than those of regular and smooth channels of the same configuration, its flow resistance situation in the slotted channel becomes quite complex; The flow resistances of 2 mm- and 4 mm-slotted channels were obviously lower than that of the regular channel, but they are still much higher than that of the smooth channel; Compared with the regular channel, the total heat transfer efficiencies of the slotted channels were pretty improved, among them the 4-mm slotted channel has the biggest enhancement. From the experimental results, it is obvious that the latticework channel with proper slots has a great prospect in the design of the inner cooling channels of turbine blades.

关键词： latticework cooling turbine blade truncated ribs heat transfer flow resistance

Effect of turbulence models on predicting convective heat transfer to hydrocarbon fuel at supercritical pressure

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Chinese Journal of Aeronautics 2016年第5期29卷 1247-1261页

作者： Tao Zhi Cheng Zeyuan zhu jianqin Li Haiwang National Key Laboratory of Science and Technology on Aero-Engine Aero-Thermodynamics School of Energy and Power Engineering Beihang University

A variety of turbulence models were used to perform numerical simulations of heat transfer for hydrocarbon fuel flowing upward and downward through uniformly heated vertical pipes at supercritical pressure. Inlet temperatures varied from 373 K to 663 K, with heat flux rang- ing from 300 kW/m2 to 550 kW/m2. Comparative analyses between predicted and experimental results were used to evaluate the ability of turbulence models to respond to variable thermophysical properties of hydrocarbon fuel at supercritical pressure. It was found that the prediction performance of turbulence models is mainly determined by the damping function, which enables them to respond differently to local flow conditions. Although prediction accuracy for experimental results varied from condition to condition, the shear stress transport （SST） and launder and sharma models performed better than all other models used in the study. For very small buoyancy-influenced runs, the thermal-induced acceleration due to variations in density lead to the impairment of heat transfer occurring in the vicinity of pseudo-critical points, and heat transfer was enhanced at higher temperatures through the combined action of four thermophysical properties： density, viscosity, thermal conductivity and specific heat. For very large buoyancy- influenced runs, the thermal-induced acceleration effect was over predicted by the LS and AB models.

关键词： Buoyancy effect Hydrocarbon fuel Supercritical pressure Turbulence models Variable properties

Numerical investigation of pyrolysis effects on heat transfer characteristics and flow resistance of n-decane under supercritical pressure

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Chinese Journal of Aeronautics 2018年第6期31卷 1249-1257页

作者： Zhi TAO Xizhuo HU jianqin zhu Hongwei WU National Key Laboratory of Science and Technology on Aero-thermodynamies School of Energy and Power EngineeringBeihang University Beijing 100083 China School of Engineering and Technology University of Hertfordshire Hatfield AL10 9AB United Kingdom

Pyrolysis of hydrocarbon fuel plays an important role in the regenerative cooling process. In this article, a Two-Dimensional（2D） numerical model is proposed to investigate the pyrolysis effects on the heat transfer characteristics and flow resistance of n-decane under supercritical pressure. The one-step global pyrolytic reaction mechanism consisting of 19 species is adopted to simulate the pyrolysis process of n-decane. The thermophysical and transport properties of the fluid mixture are computed and incorporated into the numerical model for simulation. Comparisons between the current predictions and the open published experimental data are carried out and good agreement is achieved. In order to better understand the complicated physicochemical process, further investigations on the turbulent flow and heat transfer coupled with pyrolysis in a tube have been performed under various operating conditions. The results indicate that the pyrolysis intensively takes place in the high fluid temperature region. The occurrence of the heat transfer deterioration would lead to increasing n-decane conversion at the beginning of the heated section. It is found that the pyrolysis could improve the heat transfer deterioration and promote the heat transfer enhancement. Meanwhile, pyrolysis gives rise to an abrupt increase of flow resistance. The mechanisms of the physicochemical phenomena are also analyzed in a systematic manner, which would be very helpful in the development of the regenerative cooling technology.

关键词： n-Decane Convective heat transfer Flow resistance Pyrolysis Supercritical pressure

Effect of Blockage Ratio on Heat Transfer and Pressure Drop in Rotating Ribbed Channels at High Rotation Numbers

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Journal of Thermal Science 2021年第3期30卷 902-913页

作者： DENG Hongwu LI Hua TAO Zhi QIU Lu zhu jianqin National Key Laboratory of Science and Technology on Aero-Engine Aero-thermodynamics School of Energy and Power EngineeringBeihang UniversityBeijing 100191China

At high rotation numbers,the rotational effects on heat transfer and flow could be diverse among the channels with different blockage ***,most studies are conducted under low rotation number(less than 0.25)and selected blockage *** paper experimentally investigates the effect of rib blockage ratio(ranges from 0 to 0.3)on pressure loss and heat transfer in a rotating square channel under high rotation number(up to 0.81).The ribs staggered on leading and trailing walls were oriented 90°to the mainstream *** Reynolds number and the wall-to-fluid temperature ratio varied from 20000 to 40000 and 0.08 to 0.2,*** results showed that a larger blockage ratio resulted in a better heat transfer but a higher pressure *** optimum blockage ratio was 0.1 for the best thermal *** rotational effects were weakened in the passage with a higher blockage ratio,where the critical rotation number could not be ***,the heat transfer enhancement induced by rotation was more significant when the temperature ratio ***,the correlations were developed for the pressure drop and the convective heat transfer on the leading and trailing edges.

关键词： thermal performance rib blockage ratio high rotation number

Effect of the protrusion shape on gas ingestion of two sealing structures

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Chinese Journal of Aeronautics 2021年第4期34卷 320-331页

作者： Zeyu WU Xiang LUO jianqin zhu Hang CHEN Jiahua LIU School of Energy and Power Engineering Beihang UniversityBeijing 100083China National Key Laboratory of Science and Technology on Aero-Engine Aero-Thermodynamics Beihang UniversityBeijing 100083China

The windage loss caused by protrusion in a rotor–stator cavity has been studied in detail,and there are abundant fitting formulas that have been summarized to calculate the moment *** other theorists have emphasized its effect on the sealing efficiency,proposing that installation of protrusion could alleviate gas ***,the protrusion shape which is an influential factor on the sealing efficiency has not been focused in previous *** the experimental method of measuring CO2 volume fraction,cavity pressure,and power consumption,we investigated the effects of several typical protrusion shapes on various parameters for two sealing structures,in order to obtain the optimal *** showed that a variation of the protrusion shape had little impact on the static pressure,but the total pressure and the sealing efficiency increased in different ***,even though the hexagon shape resulted in the highest sealing efficiency,we observed that the drop shape had the best overall performance in all of the eight models,which could result in higher efficiency of the turbine *** combination of a radial seal structure and protrusion could improve sealing efficiency better.

关键词： Axial seal Cavity Gas ingestion Protrusion shape Radial seal Sealing efficiency Turbine

Artificial intelligence aided design of film cooling scheme on turbine guide vane

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Propulsion and Power Research 2020年第4期9卷 344-354页

作者： Dike Li Lu Qiu Kaihang Tao jianqin zhu National Key Laboratory of Science and Technology on Aero-Engine Aero-thermodynamics School of Energy and Power EngineeringBeihang UniversityBeijing100191China

In recent years,artificial intelligence(AI)technologies have been widely applied in many different fields including in the design,maintenance,and control of *** air-cooled turbine vane is one of the most complex components in aero-engine ***,it is interesting to adopt the existing AI technologies in the design of the cooling *** that the application of AI relies on a large amount of data,the primary task of this paper is to realize massive simulation automation in order to generate data for machine *** includes the parameterized three-dimensional(3-D)geometrical modeling,automatic meshing and computational fluid dynamics(CFD)batch automatic simulation of different film cooling structures through customized developments of UG,ICEM and *** is demonstrated that the trained artificial neural network(ANN)can predict the cooling effectiveness on the external surface of the turbine *** results also show that the design of the ANN architecture and the hyper-parameters have an impact on the prediction precision of the trained *** this established method,a multi-output model is constructed based on which a simple tool can be *** is able to make an instantaneous prediction of the temperature distribution along the vane surface once the arrangements of the film holes are adjusted.

关键词： Film cooling Machine learning Fast prediction Massive simulation automation Turbine guide vane

Numerical investigation on flow and heat transfer characteristics of supercritical RP-3 in inclined pipe

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Chinese Journal of Aeronautics 2019年第8期32卷 1885-1894页

作者： Zhi TAO Liangwei LI jianqin zhu Xizhuo HU Longyun WANG Lu QIU National Key Laboratory of Science and Technology on Aero-engine Aero-thermodynamics School of Energy and Power EngineeringBeihang UniversityBeijing 100083China College of Aeronautical Engineering Civil Aviation University of ChinaTianjin 300300China

Numerical simulations of flow and heat transfer to supercritical RP-3 through the inclined tubes have been performed using LS k–e model embedded in Fluent. The physical properties of RP-3 were obtained using the generalized corresponding state laws based on the fourcomponent surrogate model. Mass flow rate is 0.3 g/s, system pressure is 3 MPa, inlet temperature is 373 K. Inclination of the inclined pipe varied from -90° to 90°, with heat flux varied from 300 k W/m^2 to 400 kW/m^2. Comparison between the calculated result and the experimental data indicates the range of error reasonable. The results of ±45° show that temperature inhomogeneity in inclined pipe produce the secondary flow in its cross section due to the buoyancy force. Depending on the strength of the temperature inhomogeneity, there will be two different forms of secondary flow and both contribute to the convective heat transfer in the pipe. The secondary flow intensity decreases when the inhomogeneity alleviates and thermal acceleration will play a leading role. It will have a greater impact on the turbulent flow to affect the convective heat transfer in the pipe. When changing the inclination, it affects the magnitude of the buoyant component in flow direction. The angle increases, the buoyancy component decreases. And the peak temperature of wall dominated by the secondary flow will move forward and increase in height.

关键词： Heat transfer Hydrocarbon fuel Inclined pipe Supercritical pressure Variable properties

Artificial neural network analysis of the Nusselt number and friction factor of hydrocarbon fuel under supercritical pressure

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Propulsion and Power Research 2022年第3期11卷 325-336页

作者： Kaihang Tao jianqin zhu Zeyuan Cheng Dike Li National Key Laboratory of Science and Technology on Aero-Engine Aero-thermodynamics School of Energy and Power EngineeringBeihang UniversityBeijing100191China

This paper presents the Nusselt number and friction factor model for hydrocarbon fuel under supercritical pressure in horizontal circular tubes using an artificial neural network(ANN)analysis on the basis of the back propagation *** derivation of the proposed model relies on a large number of experimental data obtained from the tests performed with the platform of supercritical flow and heat *** topology structures,training algo-rithms and transfer functions are employed in model *** performance of the optimal ANN model is evaluated with the mean relative error,the determination coefficient,the number of iterations and the convergence *** is demonstrated that the model has high prediction accuracy when the tansig transfer function,the Levenberg-Marquardt training algo-rithm and the three-layer topology of 4-9-1 are *** addition,the accuracy of the ANN model is observed to be the highest compared with other classic empirical *** relative error values of 4.4%and 3.4%have been achieved for modeling of the Nusselt number and friction factor respectively over the whole experimental data *** ANN model estab-lished in this paper is shown to have an excellent performance in learning ability and general-ization for characterizing the flow and heat transfer law of hydrocarbon fuel,which can provide an alternative approach for the future study of supercritical fluid characteristics and the associ-ated engineering applications.

关键词： Artificial neural network(ANN) Nusselt number Friction factor Supercritical pressure Hydrocarbon fuel

Computational research on film cooling under rotating frame by an anisotropic turbulence model

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Propulsion and Power Research 2013年第1期2卷 20-29页

作者： jianqin zhu Kai Wang Chaoqun Nie National Key Laboratory of Science and Technology on Aero-Engine Aero-Thermodynamics School of Energy and Power EngineeringBeihang UniversityBeijing 100191China Institute of Engineering Thermophysics Chinese Academy of SciencesBeijing 100190China

A new anisotropic k-o turbulence model was proposed in this *** new model,with the standard k-o model and the standard k-e model was embedded in our three-dimensional(3-D)Navier-Stokes code to compute rotational film *** addition,the theoretical and numerical analysis on the influence of the Coriolis and buoyancy forces induced by the rotation was discussed in *** findings of this study are as follows:⑴The new anisotropic k-o model preformed much better compared to its isotropic counterparts.(2)In the region of 6D-12D downstream the film hole,the numerical results of the new model were much closer to the experimental data than that in the region of 0-6D.(3)The constant density term can be balanced by the pressure gradient and would not influence the velocity and temperature *** the centrifugal buoyancy force and the Coriolis force would change the trajectory of cooling air and temperature distributions.

关键词： Film cooling Turbulence model Rotation Coriolis force Centrifugal force