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Study on dryout point and heat transfer in subcooled flow boiling through vertical narrow annular channels
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作者 DING Guo-zhong HUANG Su-yi SU Shun-yu LI Jia HU Xing-hua 《Journal of Energy and Power Engineering》 2007年第1期15-21,共7页
The purpose of this study is to conduct the dryout point and heat transfer correlation for subcooled boiling flow in narrow annuli. First, the dryout point of subcooled flow boiling of water was measured in narrow ann... The purpose of this study is to conduct the dryout point and heat transfer correlation for subcooled boiling flow in narrow annuli. First, the dryout point of subcooled flow boiling of water was measured in narrow annular channels under the working condition of pressure ranging from 0.1 to 0.3 MPa and low mass flow rate from 6 to 60 kgm^-2 s^-1. Experimental test channels were annular and heated bilaterally with the channel gap of lmm and 1.5mm, and heated length of 1500mm.The location of the dryout was observed and measured by experiment with investigating the various system parameter effects on dryout point, and the results show that the location of dryout point is basically stable and repeating and the heat transfer coefficient increased with heat flux, mass flux and pressure, however, decreases with the gap size. Next, new correlations of CHF and critical vapor quality for narrow annular channels was proposed and calculation results shown a good agreement with the experimental data. 展开更多
关键词 dryout point heat transfer subcooled flow boiling narrow annular channels
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Ice Resistance Assessment for a Large Size Vessel Running in a Narrow Ice Channel Behind an Icebreaker 被引量:2
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作者 Kirill Sazonov Aleksei Dobrodeev 《Journal of Marine Science and Application》 CSCD 2021年第3期446-455,共10页
Large size vessels sailing in continuous level ice and broken ice of high concentration are mostly assisted by icebreakers.This is done in order to provide for fast transportation through the North Sea Route and safe ... Large size vessels sailing in continuous level ice and broken ice of high concentration are mostly assisted by icebreakers.This is done in order to provide for fast transportation through the North Sea Route and safe operation in extreme ice conditions.Currently,new large size gas and oil carriers and container ships are being designed and built with beams much greater than the beams of existing icebreakers.At the same time,no mathematical description exists for the breaking mechanism of ice channel edges,when such vessels move under icebreaker escort.This paper suggests a simple method for assessment of the ice resistance in the case of a large ship running in an icebreaker channel;the method is based on modification of well-known semi-empirical methods for calculation of the ice resistance to ships in level and broken ice.The main feature of the proposed calculation scheme consists in that different methods are applied to estimate the ice resistance in broken ice and due to breaking of level ice edges.The combination of these methods gives a deliverable ice resistance of a large size vessel moving under icebreaker assistance in a newly made ice channel.In general,proposed method allows to define the speed of a carrier moving in an ice channel behind a modern linear icebreaker and could be applied at the ship design stage and during development of the marine transportation system.The paper also discusses the ways for further refinement of the assessment procedure suggested. 展开更多
关键词 Ice resistance Icebreaker assistance Large size vessels narrow ice channel Northern Sea Route Ice model tests
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Enhanced radiation-induced narrow channel effects in 0.13-μm PDSOI nMOSFETs with shallow trench isolation
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作者 张梦映 胡志远 +2 位作者 毕大炜 戴丽华 张正选 《Chinese Physics B》 SCIE EI CAS CSCD 2018年第2期619-624,共6页
Total ionizing dose responses of different transistor geometries after being irradiated by ^(60)Co γ-rays, in 0.13-μm partially-depleted silicon-on-insulator(PD SOI) technology are investigated. The negative thr... Total ionizing dose responses of different transistor geometries after being irradiated by ^(60)Co γ-rays, in 0.13-μm partially-depleted silicon-on-insulator(PD SOI) technology are investigated. The negative threshold voltage shift in an n-type metal-oxide semiconductor field effect transistor(nMOSFET) is inversely proportional to the channel width due to radiation-induced charges trapped in trench oxide, which is called the radiation-induced narrow channel effect(RINCE).The analysis based on a charge sharing model and three-dimensional technology computer aided design(TCAD) simulations demonstrate that phenomenon. The radiation-induced leakage currents under different drain biases are also discussed in detail. 展开更多
关键词 partiallydepleted silicon-on-insulator(PD SOI) totalionizingdose(TID) radiationinduced narrow channel effect(RINCE) drain induced barrier lowering(DIBL) effect
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Total ionizing dose effect in an input/output device for flash memory
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作者 刘张李 胡志远 +5 位作者 张正选 邵华 陈明 毕大炜 宁冰旭 邹世昌 《Chinese Physics B》 SCIE EI CAS CSCD 2011年第12期187-191,共5页
Input/output devices for flash memory are exposed to gamma ray irradiation. Total ionizing dose has been shown great influence on characteristic degradation of transistors with different sizes. In this paper, we obser... Input/output devices for flash memory are exposed to gamma ray irradiation. Total ionizing dose has been shown great influence on characteristic degradation of transistors with different sizes. In this paper, we observed a larger increase of off-state leakage in the short channel device than in long one. However, a larger threshold voltage shift is observed for the narrow width device than for the wide one, which is well known as the radiation induced narrow channel effect. The radiation induced charge in the shallow trench isolation oxide influences the electric field of the narrow channel device. Also, the drain bias dependence of the off-state leakage after irradiation is observed, which is called the radiation enhanced drain induced barrier lowing effect. Finally, we found that substrate bias voltage can suppress the off-state leakage, while leading to more obvious hump effect. 展开更多
关键词 input/output device oxide trapped charge radiation induced narrow channel effect shallow trench isolation total ionizing dose
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A microscopic ancient river channel identification method based on maximum entropy principle and Wigner-Ville Distribution and its application
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作者 XU Tianji CHENG Bingjie +2 位作者 NIU Shuangchen QIN Zhengye WANG Zhenzhen 《Petroleum Exploration and Development》 CSCD 2021年第6期1354-1366,共13页
In view of the problem of fine characterization of narrow and thin channels,the maximum entropy criterion is used to enhance the focusing characteristics of Wigner-Ville Distribution.On the basis of effectively improv... In view of the problem of fine characterization of narrow and thin channels,the maximum entropy criterion is used to enhance the focusing characteristics of Wigner-Ville Distribution.On the basis of effectively improving the time-frequency resolution of seismic signal,a new method of microscopic ancient river channel identification is established.Based on the principle of the equivalence between the maximum entropy power spectrum and the AR model power spectrum,the prediction error and the autoregression coefficient of AR model are obtained using the Burg algorithm and Levinson-Durbin recurrence rule.Under the condition of the first derivative of autocorrelation function being 0,the Wigner-Ville Distribution of seismic signal is calculated,and the Wigner-Ville Distribution time-frequency power spectrum(MEWVD)is obtained under the maxi-mum entropy criterion of the microscopic ancient river channel.Through analysis of emulational seismic signal and forward numerical simulation signal of narrow thin model,it is found that MEWVD can effectively avoid the interference of cross term of Wigner-Ville Distribution,and obtain more accurate spectral characteristics than STFT and CWT signal analysis methods.It is also proved that the narrow and thin river channels of different scales can be identified effectively by MEWVD of different frequencies.The method is applied to the third member of Jurassic Shaximiao Formation(J2s33-2)gas reservoir of the Zhongji-ang gas field in Sichuan Basin.The spatial information of width and direction of narrow and thin river channels with width less than 500 m and sandstone thickness less than 35 m is accurately identified,providing bases for well deployment and horizontal well fracturing section selection. 展开更多
关键词 maximum entropy principle Wigner-Ville Distribution spectral focusing high resolution SEISMIC fluvial facies narrow and thin ancient channel
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ANALYSIS AND MEASUREMENT OF STOKES LAYER FLOWS IN AN OSCILLATING NARROW CHANNEL 被引量:4
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作者 PENG Xiao-xing HSU C. T. 《Journal of Hydrodynamics》 SCIE EI CSCD 2008年第6期770-775,共6页
The velocities of boundary layer flows between two parallel oscillating plates separated by small distance, i.e., in so called narrow channel, were theoretically and experimentally studied. The focus was on the lamina... The velocities of boundary layer flows between two parallel oscillating plates separated by small distance, i.e., in so called narrow channel, were theoretically and experimentally studied. The focus was on the laminar case where the Reynolds number ReA is much smaller than the transition value. The theoretical analysis of the Stokes layer in oscillating flow over a narrow channel was made first. Then Laser Doppler Velocimeter (LDV) was employed to measure the Stokes boundary layer above an oscillating flat plate and inside the oscillating narrow channel at various ReH numbers. At the same time, the phase angle difference along the vertical direction in both analysis and experiment were provided. The good agreements are shown between the measured results and the theoretical solution. 展开更多
关键词 oscillation flow Stokes layer Laser Doppler Velocimeter (LDV) narrow channel
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A NOTE ON THE NARROW OPEN CHANNEL RESONANCE 被引量:4
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作者 Miao Guo-ping (School of Naval Architecture and Ocean Engineering, Shanghai Jiaot ong University, Shanghai 200030, China) H.Ishida, T.Saitoh (Department of Civil Engineering, Kanazawa University, Japan) 《Journal of Hydrodynamics》 SCIE EI CSCD 2002年第1期29-37,共9页
A narrow open channel resonant phenomenon, newly found by the authors in corresponding numerical calculations , was proved to exist based on the method of matching asymptotic expansions for three different channel co... A narrow open channel resonant phenomenon, newly found by the authors in corresponding numerical calculations , was proved to exist based on the method of matching asymptotic expansions for three different channel configurations. It is shown that the resonant wave numbe rk emerges around kL=nπ, n=1,2,3,…∞ with a corresponding frequency s hift, where L is the length of the channel. It is also clear that the resona nce in a narrow open channel is an essential property of a channel as long as it is uniformly narrow. 展开更多
关键词 narrow open channel RESONANCE the method of matching asymptotic expansions wave diffraction multiple bodies
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Study on the pre-ignition characteristics of wire insulation in the narrow channel setup 被引量:2
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作者 WANG Kai WANG BaoRui +1 位作者 AI YuHua KONG WenJun 《Science China(Technological Sciences)》 SCIE EI CAS 2012年第8期2132-2139,共8页
A narrow channel setup was established and experiments were conducted to study the pre-ignition characteristics of wire insulation under overload conditions in weak buoyancy environment.The pre-ignition temperature va... A narrow channel setup was established and experiments were conducted to study the pre-ignition characteristics of wire insulation under overload conditions in weak buoyancy environment.The pre-ignition temperature variation trend of both the wire insulation and its nearby temperature monitoring points,the movement characteristics of smoke produced from the wire insulation and the ignition delay time of wire insulation were investigated.The results indicated that the narrow channel setup with a height of 10-15 mm was effective to suppress the effect of buoyancy,and the pre-ignition characteristics of wire insulation in microgravity could be predicted well by the narrow channel method. 展开更多
关键词 MICROGRAVITY narrow channel method wire insulation pre-ignition characteristics
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Heat transfer characteristics in a narrow confined channel with discrete impingement cooling 被引量:1
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作者 Yang LI Tao LIU +2 位作者 Jianjun TAO Weihua YANG Likun DONG 《Chinese Journal of Aeronautics》 SCIE EI CAS CSCD 2022年第4期220-229,共10页
Heat transfer characteristics in a narrow confined channel with discrete impingement cooling were investigated using thermal infrared camera. Detailed heat transfer distributions and comparisons on three surfaces with... Heat transfer characteristics in a narrow confined channel with discrete impingement cooling were investigated using thermal infrared camera. Detailed heat transfer distributions and comparisons on three surfaces with three impact diameters were experimentally studied in the range of Reynolds number of 3000 to 30000. The experimental results indicated that the strong impingement jet leaded to a high strength heat transfer zone in the ΔX=±2.5D;range of the impact center,which was 1.3–2.5 times of the average heat transfer value of the impingement wall. With the same coolant mass flow rate, small diameter case had lower heat transfer coefficient on both inner wall and outside wall, while the impingement wall was insensitive to the impact diameter. The surface averaged Nusselt number of inner wall was only 43%–57% of impingement wall, while the outside wall can reach up to 80%–90%. The larger the diameter, the higher heat transfer enhancement and the smaller the channel flow resistance was observed in term of Reynolds number. The surface averaged Nusselt numbers were developed as the function of Reynolds number and the impingement height-to-diameter for further engineering applications. 展开更多
关键词 AERO-ENGINE Heat transfer characteristics Impingement cooling narrow confined channel Turbine blade
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Can the narrowing of the Lower Yellow River by regulation result in non-siltation and even channel scouring? 被引量:1
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作者 SUN Zanying WANG Wanzhan +3 位作者 LI Yong ZHANG Mingwu SHANG Hongxia ZHANG Fangxiu 《Journal of Geographical Sciences》 SCIE CSCD 2016年第9期1337-1348,共12页
This study considered whether the narrowing of the upper (broad and wandering) reaches of the Lower Yellow River could result in a reduction in sedimentation and even an increase in channel erosion in both the upper... This study considered whether the narrowing of the upper (broad and wandering) reaches of the Lower Yellow River could result in a reduction in sedimentation and even an increase in channel erosion in both the upper and the lower (narrow and meandering) reaches. Analysis of field data and numerical modeling results both justify the proposal to narrow the channel. A positive correlation was found between channel eroded-area and the channel width. Therefore narrowing under conditions of low flow will reduce the amount of erosion in the reach, which, in turn, will reduce the amount of sediment transported into the lower channel. This will reduce the amount of siltation in the lower reaches of the river. However, narrowing under conditions of high flow with a low concentration of sediment will reduce both the extent of flood attenuation along the narrowed channel and the amount of lateral channel bank collapse, which results in increased flows and less sedimentation in the lower channel, leading to increased erosion. When flows with a high concentration of sediment are released from the Xiaolangdi Reservoir, both the lower narrow channel and the upper channel can transport a large amount of the sediment load. It is concluded that the narrowing of the upper broad channel will result in a reduction in sedimentation, or even in channel erosion, in both the upper and the lower channels if the reservoir is operated such that the volume of sediment added during low flows is balanced by the volume eroded during high flows with a low concentration of sediment. 展开更多
关键词 channel narrowing sediment release sediment transport capacity Lower Yellow River XiaolangdiReservoir
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Prediction of Turbulent Flow Structure in a Fully Developed Rib-Roughened Narrow Rectangular Channel
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作者 Md.Shafiqul Islam M.Kaminaga +1 位作者 R.Hino M.Monde 《Journal of Thermal Science》 SCIE EI CAS CSCD 2009年第2期126-136,共11页
Fully developed turbulent water-flow structure over one-side repeated-ribs in narrow two-dimensional rectangular channels was investigated experimentally by Particle Image Velocimetry (PIV) and analytically by the s... Fully developed turbulent water-flow structure over one-side repeated-ribs in narrow two-dimensional rectangular channels was investigated experimentally by Particle Image Velocimetry (PIV) and analytically by the standard k-ε and nonlinear k-ε turbulent models. Two rib-pitch to height ratios (p/k) of 10 and 20 were investigated while the rib height was held constant at 4 mm. The rib height-to-channel equivalent diameter ratio (k/De) was 0.1. The streamwise mean velocity and turbulent kinetic energy distributions at six selected axial stations from the center rib for the two Reynolds number (Re) of 7,000 and 20,000 were obtained and compared with the predicted one. The performance ability in predicting separating and reattaching turbulent water-flow between the standard K-ε and nonlinear k-ε models had yielded no clear conclusion. A large-scale turbulent eddy was generated by the rib promoter and then propagated into the mainstream flow, which led to the deformation of the velocity profile. The turbulent kinetic energy was increased about two times higher at p/k = 20 than that at p/k =10 under the two Reynolds numbers. The effect of the p/k value and the Reynolds number (Re) on reattachment length (XR) was investigated and showed that the p/k and Re had no significant effect on the reattachment length beyond a critical value of Re = 15,000 where XR was found to be approximately 4 times of the rib height under water-flow condition. 展开更多
关键词 Turbulent water-flow structure repeated-ribs narrow rectangular channels two-dimensional analysis reattachment length
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On Problems with Downscaling in Internal Flows
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作者 Rudolf DVO■K 《Journal of Thermal Science》 SCIE EI CAS CSCD 2005年第4期305-307,共3页
Problems that may accompany downscaling in internal flows are discussed. Non-dimensional similarity parameters (like Re, M, etc.) depend on parameters that scale down fully (e.g., length), or that are specified by... Problems that may accompany downscaling in internal flows are discussed. Non-dimensional similarity parameters (like Re, M, etc.) depend on parameters that scale down fully (e.g., length), or that are specified by design (velocities, cascade geometry), or that are scale invariant (like thermophysical and transport properties of fluids).This fact has to be taken into acount in the similarity considerations. With decreasing Reynolds number the surface forces become of growing importance, however, if not going down directly to microflows the main problems are connected with the three-dimensional flow structure affecting the skin friction, and with the fact that some of the flow phenomena (e.g. vortical structures) cannot fully develop. 展开更多
关键词 relatively narrow channels secondary flows skin friction microturbines.
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Pressure Wave and Fluid Velocity in a Bend-Mode Inkjet Nozzle with Double PZT Actuators 被引量:3
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作者 Sungu Kim Jaeyong Sung Myeong Ho Lee 《Journal of Thermal Science》 SCIE EI CAS CSCD 2013年第1期29-35,共7页
A new concept of bend-mode inkjet nozzle with double PZT (lead zirconate titanate) actuators has been designed and fabricated in the present study. Then the pressure wave and fluid velocity at the nozzle exit have bee... A new concept of bend-mode inkjet nozzle with double PZT (lead zirconate titanate) actuators has been designed and fabricated in the present study. Then the pressure wave and fluid velocity at the nozzle exit have been investigated. The complex pressure behavior inside the channel was solved numerically based on the narrow channel acoustic theory. The two PZTs attached to a rectangular channel were actuated sequentially by setting the waveforms of each PZT to be center-aligned with various pulse widths. As a result, the double PZT actuation is superior to the single PZT actuation in view of strong momentum force and fast dissipation of residual pressure. The maximum fluid velocity at the nozzle exit is observed when the respective pulse widths equal to their optimum pulse widths. The numerical results are supported by the experimental results with the fabricated inkjet device by measuring the speed of meniscus just out of the nozzle. 展开更多
关键词 double PZT actuators inkjet nozzle narrow channel theory pressure wave sequential actuation
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