核动力工程

Experimental Research on Single Phase Flow and Convection Heat Transfer in Heat-Generating Porous Media

ZHANG Zhen, YAN Xiao, XIAO Ze-jun

2012, 33(S1): 1-4.

Abstract(16) PDF(0)

Abstract:
An experiment was conducted to study the flow resistance and convection heat transfer char-acteristics of single phase in heat-generating porous media,within the range of Reynolds number from 127~394,and heat flux from 12~62 kW/m².The experimental correlations of the flow resistance and convec-tion heat transfer coefficient were obtained.The experimental results indicated the effect of Reynolds number on the inertia coefficient Rf.Based on Ergun correlation,modifying the inertia coefficient,a new flow resistant calculated correlation was obtained.The correlation can well predict the flow resistance of single phase water or single phase steam in non-heat-generating porous media with multi-geometrical parameters.The experi-mental data also indicated that the convection heat transfer coefficient decreases with the increasing of heat flux,and increases with the increasing of mass flux.

Study on Bubble Departure Frequency in Subcooled Boiling Flow under Narrow Rectangular Channel

HONG Gang, YAN Xiao, HUANG Hong-li, XIAO Zejun, HUANG Yan-ping

2012, 33(S1): 5-9.

Abstract(23) PDF(0)

Abstract:
A visual study on forced convection subcooled water boiling experiments was conducted in vertical upward narrow rectangular channels by using the high-speed digital video camera.The results show that the increasing of mass flux or subcooled inlet causes the decreasing of bubble frequency,and the increas-ing of the heat flux causes the increasing of bubble frequency.Existing models were compared with the ex-perimental data of bubble frequency.The correlations developed for the pool boiling or saturated boiling do not work well for subcooled boiling flow.A dimensionless bubble departure frequency correlation has been sought for the influence of mass flux,subcooled flow and heat flux by using the dimensionless number of Reynolds number,Jacob number and dimensionless nucleate boiling heat flux.The proposed model agreed with the experimental data within the averaged relative deviation of ±17.1%.

Distribution of Sliding Bubble Diameter along Axial Direction in Narrow Rectangular Channel

HONG Gang, YAN Xiao, LI Yan, XIAO Ze-jun, HUANG Yan-ping

2012, 33(S1): 10-13.

Abstract(16) PDF(0)

Abstract:
A visual study on forced convection subcooled water boiling experiments was conducted.A high speed camera was used to capture the distribution of sliding bubble diameter along axial direction in the narrow rectangular channel.The consecutive images of sliding bubbles coalescence were captured.Bubble diameter distribution on axial direction of 300,400 and 500 mm was achieved.The results show that the in-creasing of the axial direction causes the increasing of the sliding bubble diameter.The growth of sliding bubble along heating surface,the coalescence of bubbles between slipping bubble and the wall-attached bub-ble,and the coalescence of slipping bubbles are the main reason.

Potential Function and Vector Algebraic Integral Method of Additional Pressure Drops in Arbitrary Pipes under Ocean Conditions

MA Jian, HUANG Yan-ping, LI Long-jian

2012, 33(S1): 14-18.

Abstract(14) PDF(0)

Abstract:
Pipe parallel and rolling motions will result in additional pressure drops because of the intro-duction of additional body forces under ocean conditions.To obtain universal and convenient analytical solu-tions to additional pressure drops,this paper starts with the hydrodynamic momentum equation in the non-inertial frame.The pipe motion is divided into parallel motion and rolling motion.The analytical solu-tions to additional pressure drops respectively induced by parallel motion and rolling centrifugal force are achieved by means of hydrodynamics potential function analysis.This paper also starts with mathematical and physical definitions of additional pressure drops.The pipe rolling motion is divided into vertical rolling and parallel rolling.The analytical solution to additional pressure drops induced by rolling tangential force is achieved by using the vector algebraic integral method.Finally,the applicability of these solutions is dis-cussed.The analytical results show that each additional pressure drop in an arbitrary pipe under ocean condi-tions can be resolved accurately.

Experimental Study of Performance Parameters of a Fluid Densimeter with Vibrated Conduit

LV Fa, ZHANG Xiao-zhang

2012, 33(S1): 19-22.

Abstract(12) PDF(0)

Abstract:
Experimental study of performance parameters of a fluid densimeter with vibrated conduit was carried out,using single-phase water and air-water two-phase flow with different vapor quality to modulate the fluid of different density.The results indicated that the parallel vibrating model of the vibrated conduit is more suitable for measuring the fluid density than the wiggling mode around the center of the vibrated conduit.The measuring of the fluid density is under the influence of the oscillation of the system and the pressure of the fluid.System oscillation should be limited and expressions modified by fluid pressure are presented.The experimental results also indicated that the change of the flowrate nearly has no impact on the performance parameters of the fluid densimeter with vibrated conduit.

Research on Bubble Departure Diameter in Narrow Rectangular Channel

XIE Tian-zhou, CHEN Bing-de, YAN Xiao, XU Jian-jun, XIAO Ze-jun

2012, 33(S1): 23-27.

Abstract(16) PDF(0)

Abstract:
The effect of heat flux,inlet sub-cooling and mass flow rate on bubble departure diameters was investigated in narrow rectangular channel using water as the working fluids.The experiment was done at pressure of about 0.16 MPa.The mass flow rate were between 300 and 700 kg/（m².s）;heat flux were between 27.6 and 228.3 kw/m²;and inlet sub-cooling were between 20 and 40℃.The bubble departure diameter was found not significantly affected by changes in heat flux and inlet sub-cooling while decreased for increasing mass flow rate.

Summarization and Evaluation of Supercritical Heat Transfer Correlations

HUANG Zhi-gang, CENG Xiao-kang, LI Yong-liang, YAN Xiao, XIAO Ze-jun, HUANG Yan-ping

2012, 33(S1): 28-31.

Abstract(18) PDF(0)

Abstract:
There is no phase change with the increasing of temperature under supercritical pressure.Most of the existing supercritical heat transfer correlations have the general form of single phase heat transfer cor-relations at sub-critical conditions with some modifications.The supercritical heat transfer correlations are summarized in this paper.The comparison of the correlations with the experiment data shows that Bishop and Jackson correlation fit well with the experiment data,and the correlation of this type is more accuracy than others.

Investigation on Scaling Criteria of Secondary Side Passive Residual Heat Removal System

ZHOU Lei, YAN Xiao, XI Zhao, XIONG Wan-yu, XIAO Zejun

2012, 33(S1): 32-36,94.

Abstract(18) PDF(0)

Abstract:
The governing equations for the natural circulation processes in the secondary passive residual heat removal system（PRHR） were derived in this paper.With proper reference parameters,the equations were nondimensionalized and the similarity groups for the system were achieved.The specialty of the study is the treating of the two coupled natural circulation processes.The choosing and nondimensionalization of the en-ergy equation has also some advantages over the existing researches.

Analysis of Flow Instability Types and Dynamic Behaviors for Supercritical Water

XIONG Ting, YAN Xiao, HUANG Shan-fang, HUANG Yan-ping

2012, 33(S1): 37-40,44.

Abstract(21) PDF(0)

Abstract:
Numerical analysis has been carried out for supercritical flow instability in two parallel chan-nels by applying in-house code SCIA.The dynamic behaviors during flow oscillation have been analyzed.Curves of pressure drop versus flow rate are obtained.Results show that the period of supercritical flow in-stability is 1~2 times of the fluid transit time;the propagation of mass flux perturbations delays between inlet and outlet;and mass flux perturbations propagate faster in pseudo-critical region than other regions.The similarities between supercritical flow dynamic behaviors and the density wave oscillations（DWO） charac-teristics indicate that DWO exits in supercritical region,while the curves of pressure drop versus flow rate show that the Ledinegg instability can hardly occur.

Numerical Simulation of Supercritical Water Heat Transfer Characteristics in Annular Channel

LIU Lei, XIAO Ze-jun, YAN Xiao, CENG Xiao-kang, LI Yong-liang, HUANG Yan-ping

2012, 33(S1): 41-44.

Abstract(13) PDF(0)

Abstract:
A numerical simulation was carried out to study the heat transfer characteristics of supercriti-cal water in annular channel using CFX 11.0.Wall temperature and heat transfer coefficient variation trends in smooth annular channel were compared with those in annular channel with ribs.The shape,height,distance and thickness of ribs were studied as the important influence factors on heat transfer of supercritical water in this paper.The results show that local heat transfer enhancement occurs near ribs.It also can be found that the effect of rib shape on heat transfer is negligible.Increasing the ribs height and decreasing the ribs distance are good for improving heat transfer in a certain range.The effect of rib width on heat transfer is also negligible in a certain range.

Investigation on Flow Resistance Coefficient of Wires Wrapped Tight Lattice Rods Bundle

GONG Hou-jun, LANG Xuemei, XIE Feng

2012, 33(S1): 45-49.

Abstract(18) PDF(0)

Abstract:
Experimental study on flow resistance coefficient of tight lattice fuel assemblies was per-formed,and a new correlation was proposed.Comparison between new correlation and typical Rehme corre-lation shows the latter correlation is not suitable for the test section.CFD study with SST model was per-formed to simulate experiments and analyze flow field,pressure field and flow resistance coefficient.The re-sults show that CFD method can be a reference for the prediction of single phase flow resistance of wires wrapped tight lattice rods bundle.

Experimental Research on Mixture Coefficient in Tight Fuel Assembly

XIE Feng, CAO Nian, LANG Xuemei, XIONG Wan-yu, GONG Hou-jun

2012, 33(S1): 50-53,58.

Abstract(16) PDF(0)

Abstract:
Mixture Coefficient is an important parameter for thermal hydraulic analysis.This paper introduces the structure of the test section,the content and method for and the results from the experiment for tight fuel assembly which is consist of 19 rods.The distribution of temperature and β-Reynolds number relation for the tight rods was obtained,and the bond of mixture rate and the effect of thermal hydraulic parameter on the mixture rate were analyzed.

Frictional Resistance Characteristics of Single-Phase Flow in Narrow Rectangular Channel with Rolling Motion

LIU Xiao-zhong, HUANG Yan-ping, MA Jian, HUANG Jun

2012, 33(S1): 54-58.

Abstract(18) PDF(0)

Abstract:
Experimental investigation and numerical calculation were carried out on frictional resistance characteristics of single-phase flow with rolling motion.Results indicated that the flow field was affected by the rolling motion,but the local velocity change was too small to impact the frictional resistance characteris-tics within the experiment parameter range.The formula for frictional resistance calculation obtained with standstill works well with rolling motion.

Effect of Rolling on Characteristics of Single-Phase Water Flow in Narrow Rectangular Channel

XING Dianchuan, YAN Chang-qi, CAO Xia-xin, JIN Guang-yuan

2012, 33(S1): 59-63.

Abstract(17) PDF(0)

Abstract:
Effect of rolling on characteristics of single-phase flow in narrow rectangular channel is in-vestigated experimentally under ambient temperature and atmospheric pressure.The results show that the frictional coefficient and Reynolds number fluctuate periodically when driven pressure head is low,and the more acute the rolling movement,the larger the fluctuant amplitude.When the driven pressure head is high,periodical fluctuate of Reynolds numbers is not obvious,and the amplitude of the friction coefficient fluctua-tion becomes smaller.For the case that test sections with outlet open to atmosphere,the rolling amplitude not only influences the fluctuant amplitude of the friction coefficient but also changes its waveform.The rolling period only has effect on the amplitude.The effect of rolling on the friction characteristics decreases as the mean Reynolds number increases.There is no obvious effect of rolling motions on the mean frictional char-acteristics of the single-phase water flow in narrow rectangular channel.

Preliminary Experimental Study on Geysering Phenomena in Heating System

QI Zhan-fei, TONG Lili, CAO Xue-wu

2012, 33(S1): 64-68.

Abstract(23) PDF(0)

Abstract:
The geysering phenomena is studied experimentally under several cases with different height of upper plenum,diameter of vertical column and heating power,to investigate the effects on the geysering phenomenon.According to the analysis of experimental phenomenon and data,it is found that the liquid pe-riodically boils and various flow patterns alternately occur in the heating system.The refilling of cooler liquid causes significant change of temperature and pressure in the system.The geysering phenomena is more obvi-ous under greater height of upper plenum,less diameter of vertical column and greater heating power.The effect of other system parameters on geysering requires further study in the future work.

Transient Simulation Code for Flow Boiling Based on Two-Fluid Model

REN Zhi-hao, KUANG Bo, HU Shang-wu

2012, 33(S1): 69-74.

Abstract(14) PDF(1)

Abstract:
Based on the coupling of two-fluid and wall dynamics models,and selection of specific corre-lation combination,a transient simulation code on flow boiling and heat transfer analysis within heated chan-nel is developed.Through benchmark simulation on different flow boiling cases with various inlet parameters transients,capabilities of the code transient simulating flow boiling behaviors is validated.Furthermore,the fluid-wall heat coupling simulation function of the code are tested through case studies on boiling heat trans-fer under different wall heating conditions.Starting from the present basis,the program is expected to be fur-ther developed forwarding to both system analysis and sub-channel analysis codes,which might demonstrate its feature of expansion and prospect of practical applications.

Characteristics of Effect of Vapor Bubble Behavior on Pressure Drop in Vertical Rectangular Narrow Channel

CHEN De-qi, REN Song, PAN Liang-ming, YUAN De-wen, LIU Bin

2012, 33(S1): 75-79,84.

Abstract(20) PDF(0)

Abstract:
A visual experimental study on flow boiling in vertical rectangular narrow channel was carried out,in order to investigate the effect of vapor bubble behavior on the characteristics of pressure drop.It was found that the OSV（Onset of Significant Vapor） could emerge earlier in narrow channel than in conventional channel with identical working thermal conditions.A correlation for predicting the real vapor quality and real vapor fraction was proposed based on the experimental result.It was also found that the vapor bubble behav-ior affected the pressure drop in narrow channel significantly,and the channel was blocked easily due to the vapor cluster formed in the narrow channel;the total pressure drop,however,did not increase linearly with the increasing of outlet vapor fraction.

Experimental Investigation on Frictional Pressure Drop of Single-Phase Water in Helical Coils at High and Supercritical Pressure

MAO Yu-fei, GUO Lie-jin, BAI Bo-feng, ZHEN Fei-qiang, GUO Meng

2012, 33(S1): 80-84.

Abstract(17) PDF(0)

Abstract:
The frictional pressure drop characteristics of single-phase water were experimentally studied in a vertically-oriented helically-coiled tube at high and supercritical pressure.Experiments were performed in wide ranges of Reynolds number.For the hydraulic roughness region with high Reynolds numbers at high pressure,the effect of surface roughness on frictional pressure drop is much higher than that of secondary flow.The frictional pressure drop of single-phase water in helical coils can be predicted by related equations just for straight tubes.For the pseudo-critical region with the great variation in the physical properties at supercritical pressures,the frictional pressure drop calculated by related equations for high pressure cases was obviously smaller than experimental data.

Experimental Study on Forced Convective Heat Transfer in Structured Packed Porous Media with Spherical or Ellipsoidal Particles

YANG Jian, YAN Xiao, CENG Min, WANG Qiuwang

2012, 33(S1): 85-89.

Abstract(15) PDF(3)

Abstract:
In this paper,the fraction factors and interstitial heat transfer coefficients in the packed porous media of spherical or ellipsoidal particles are experimentally investigated with an inverse method of transient single-blow technique.The effects of packing form and particle shape are carefully investigated.It was found that,with proper selection of particle shape and packing model,the overall heat transfer performance of porous media will be improved significantly.Furthermore,the traditional correlations for flow and heat transfer from randomly packed porous meia would not be suitable for structured packed porous media.

Analytical Model for CHF in Narrow Gaps Concerning Surface Orientation

ZHANG Ya-pei, TIAN Wen-xi, QIU Sui-zheng, SU Guang-hui, YU Hong-xing, YAN Xiao

2012, 33(S1): 90-94.

Abstract(14) PDF(0)

Abstract:
The CHF in rectangular narrow gaps have been investigated to develop a reasonable predictive model on CHF concerning surface orientation effects.The model is based on the counter current flow limita-tion（CCFL） by flooding of the flow entering gap.The results by the predictive model were compared with the experimental data by Kim and Suh（2003）,and a good agreement was obtained in case of 1 mm and 2 mm gap size with surface inclination angle ranging from 10°-90°.However,when the surface inclination angle is less than 10°（nearly downward-facing position）,the predictive model underestimated the CHF.The reason may be that the heating surface is covered by a stable vapor film and the vapor film is almost stationary,and that the effects of CCFL on CHF became smaller.A modified Katto-Kosho correlation was further proposed and it could predict the CHF well for inclination angle less than 10°.For gap size equaling to 5 mm and 10 mm,the predictive results were far larger than experimental data by Kim and Suh,which indicated that the validity of model based on CCFL controlled CHF was limited to gaps of less than 2 mm.

Numerical Investigation of Local Thermal Non-Equilibrium Natural Convection in a Square Enclosure with Heat Generating Porous Medium

TIAN Lin, HUANG Zi-peng, WANG Gang

2012, 33(S1): 95-99,103.

Abstract(15) PDF(0)

Abstract:
Effect of Ra number and Da number on steady laminar natural convection in square enclosure filled with heat generating porous medium is investigated by local thermal non-equilibrium model and non-Darcy model numerically with the effective fluid-to-solid thermal conductivity ratio as constant.It is found that the Nuf increases with the increasing of Da when Ra is constant;Moreover,Nuf increases with the increasing of Ra when Da is constant.However,the values of Nus of the four walls are almost the same and equal to a constant for the cases discussed.The absolute value of Nuf of left wall is equal to that of right wall,furthermore,both of them are less than that of the ceiling wall,the heat transfer between fluid and bottom wall is the smallest compared with those of the other three walls.The non-equilibrium effect is significant when dimensionless volume heat transfer coefficient H is quite small.

Calculation and Test of Core Flow Rate Distribution of China Experimental Fast Reactor

LIU Yi-zhe, XUE Xiu-li, XU Yi-jun, FENG Yu-heng, HOU Zhi-feng

2012, 33(S1): 100-103.

Abstract(15) PDF(0)

Abstract:
Based on the core and primary circuit design of China Experimental Fast Reactor（CEFR）,a multiple-channel thermal-hydraulic analysis code DAEMON was developed to calculate the core flow rate distribution and unsymmetric coefficient in different conditions.In the commissioning stage,a series of full-scale tests for reactor core were performed in CEFR with a permanent-magnet sodium flow meter.The numerical results of code DAEMON showed a good agreement with test data.The core hydraulic design was also validated with a view to the requirements of design criteria,commissioning and operation specifications.

Hydrogen Risk Assessment in SAMG and Simulation

YAO Shi-xue, ZHAN Jing-xiang, LIU Jian-ping

2012, 33(S1): 104-106,110.

Abstract(12) PDF(0)

Abstract:
In this paper,a tool used in SAMG to assess the hydrogen flammability and hydrogen impact when depressurizing containment is built.The station black out scenario is simulated with code,and hydrogen risks at different phase of the accident are analyzed.The results show that in the SBO scenario without hydrogen recombiners,the atmosphere will be inerted by steam for a while.But if the power recovers,and the containment is depressurized by spray,there will be risk of hydrogen burn and overpressure.In the scenario with hydrogen recombiners,there is no risk of overpressure,and the result is conservative.

Analyses of Effect of SG Tube Thickness on Induced-SGTR and Effectiveness of Mitigation Measures

YANG Ying-hao, PENG Chang-hong, ZHANG Jia-jia

2012, 33(S1): 107-110.

Abstract(12) PDF(0)

Abstract:
The adverse conditions in a severe accident,such as repeated alternation of cold and hot conditions or the pressure difference between RCS（Reactor Coolant System） and the secondary side,may induce the creep rupture of steam generator tubes.Based on the typical accident sequences defined by level 1 PSA analysis,this study identifies the effect of thickness reduction of steam generator tubes on inducing SGTR and analyzes the effectiveness of severe accidents mitigation measures,such as RCS depressurization and recovery of feedwater to SG.

Analysis of Flow Behavior of Coolant in Natural Circulation Reactor Based on Computational Fluid Dynamics

LU Chuan, ZHANG Yong, LU Jian-chao, DONG Hua-ping

2012, 33(S1): 111-114,118.

Abstract(19) PDF(0)

Abstract:
Flow behavior of coolant in natural circulation reactor was analyzed by CFD.The analysis found that the results of flow field calculated by SST and SSG turbulence models are basically same,and the results of flowrate calculated by CFD and Relap5 are also basically same.From CFD calculations,the flow distributions were symmetrical at the lower plate,which showed that the minimal mass flow factor was 0.93.Flow distributions could be adjusted by closed core channels and chimneys,which gave the better results.

Selection of Natural Circulation Valve Diameter and Experiment Verification for Research Reactor

HUANG Hong-wen, LIU Han-gang, XU Xian-qi, QIAN Da-zhi

2012, 33(S1): 115-118.

Abstract(13) PDF(0)

Abstract:
Based on different natural circulation valve diameters of 150mm,200mm,250mm and 300mm.RETRAN-02 code is used to calculate the flow of the natural circulation valve（NCV） and the hot channel,the temperature of the hot spot,the minimum departure from nuclear boiling ratio（MDNBR）,and to analyze the safety of thermo-hydraulic parameter from the two aspects of NCV abnormal open and the establishment of natural circulation.It is proved that the NCV diameter of 200 mm is suitable.

Application of Reactor Protection by Linear Power Rate and DNBR in Tianwan NPS

YAO Jin-guo, YANG Xiao-qiang, LI Zai-peng, LI You-yi, YANG Gao-sheng

2012, 33(S1): 119-122.

Abstract(18) PDF(0)

Abstract:
As the main sub-system of Monitoring,Control and Diagnostic System for Tianwan NPS,In-Core Instrumentation System carries out the function of calculating and monitoring the real-time parameters of the reactor during normal operation and transient condition.For the first time,linear power rate of fuel rods and DNBR are used as on-line safety protection signals to ensure the safety and economical operation of the reactor.

2012 Vol. 33, No. S1