Journal of Engineering Thermophysics最新文献

{"title":"The Impact of Impingement Surface Angle Variation and Channel Design on Heat Transfer Performance and Flow Characteristics for Twin Jet Impingement","authors":"K. Karabulut,&nbsp;Y. Alnak","doi":"10.1134/S181023282501014X","DOIUrl":"10.1134/S181023282501014X","url":null,"abstract":"<p>This study intends to give a detailed research of surface angles of impingement, and jet-plate distances to enhance heat transfer and improve the channel’s flow structure features for twin jet impingement. For this aim, numerical analysis of twin jet impingement was carried out for distinct impingement surface angles (<span>(alpha)</span>) of 30°, 45°, and 60° and impinging jet-plate distances (H) of 3, 4.5, and 6. The numerical investigation was performed as a steady, two-dimensional, employing the <span>(k)</span>-<span>(varepsilon)</span> turbulence model and the Ansys–Fluent program in the twin jet rectangular channel. While the isothermal flat plate impingement surface has 310 K (T<span>(_{{rm H}})</span>), the impinging air jet fluid temperature is 300 K (T). The obtained outcomes were compared with the numerical and experimental outcomes of the work in the literature and it was noticed that they are determined to be compatible. The results were presented as the local Nu number (Nu<span>(_{L})</span>) variations for <span>(alpha=30^{circ})</span>, 45° and 60° impingement surface angles along the flat plate impingement surface, and the variations of mean Nu numbers (Nu<span>(_{m})</span>) for different <span>(alpha)</span> and H values with the Re number ranges of 20000–50000. Besides, streamlines and temperature isotherms were evaluated for different <span>(alpha)</span>, H and Re number values by visualising them in detail. The results displayed that while the Nu<span>(_{m})</span> values are higher than the case without angle (<span>(alpha=0^{circ})</span>) for all angles and H values, after the 30° angle, the Nu<span>(_{m})</span> values decrease slightly at 45° and 60°. Accordingly, for H = 6, the Nu<span>(_{m})</span> value of 30° impingement surface angle is 3.09% higher than that in 60°.</p>","PeriodicalId":627,"journal":{"name":"Journal of Engineering Thermophysics","volume":"34 1","pages":"162 - 179"},"PeriodicalIF":1.3,"publicationDate":"2025-04-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143848925","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Correcting Spectral Density of Laser Doppler Anemometer Signals during Measuring of High-Speed Aerodynamic Flows. Part 2","authors":"I. K. Kabardin,&nbsp;V. V. Rakhmanov,&nbsp;A. V. Klimov,&nbsp;V. G. Glavnyi,&nbsp;D. V. Kulikov,&nbsp;V. G. Meledin,&nbsp;S. V. Dvoinishnikov,&nbsp;V. O. Zuev,&nbsp;G. V. Bakakin,&nbsp;V. A. Pavlov","doi":"10.1134/S1810232825010035","DOIUrl":"10.1134/S1810232825010035","url":null,"abstract":"<p>A method has been developed for constructing correction factors to compensate for distortions introduced by non-uniform frequency characteristics of the electronic path of a laser Doppler velocimeter into the spectral density of Doppler signals. The method relies on averaging a statistical ensemble of spectral densities of noise signals obtained during illumination of a photodetector with a reference white light source, constructing the inverse function to the resulting averaged spectral density with truncation in the low- and high-frequency bands, and applying digital low-pass filtering to it. In the first part, a model numerical experiment was carried out. The gas flow velocity at the Vitoshinsky nozzle exit was measured with a laser Doppler anemometer in high-velocity modes. It has been shown that in high-velocity modes (200 m/s), the application of correction factors to the spectral density of Doppler signals allows estimating the average flow velocity with an error of no more than 5%, while calculating velocities without preliminary correction of the spectral density leads to statistical measurement errors of more than 100%.</p>","PeriodicalId":627,"journal":{"name":"Journal of Engineering Thermophysics","volume":"34 1","pages":"25 - 34"},"PeriodicalIF":1.3,"publicationDate":"2025-04-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143848964","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Experimental Observations of Meridional Flow Stagnation in a Three-Fluid Vortex","authors":"M. V. Tintulova,&nbsp;I. V. Naumov,&nbsp;B. R. Sharifullin,&nbsp;V. N. Shtern","doi":"10.1134/S1810232825010059","DOIUrl":"10.1134/S1810232825010059","url":null,"abstract":"<p>In the search for a flow pattern optimal for culture growth in vortex bioreactors, our experiments discovered unusual flow structures that existing theoretical models cannot explain. Three immiscible liquids fill a vertical open cylindrical container of radius R = 47 mm whose sidewall is still while the bottom disk rotates driving a fluid motion. The centrifugal force pushes the lower liquid (L, aqueous glycerol) from the axis to the periphery near the bottom, creating its toroid circulation that in turn drives toroid circulations of the middle liquid (M, sunflower oil) and the upper liquid (U, alcoholic glycerine). With increasing rotation, counterflows develop near interfaces LM and MU: the liquids move towards (away from) the axis below (above) the interface that seems paradoxical. At a small thickness of M, a stagnation zone arises where the axial and radial velocities vanish and the M liquid only rotates. As M thickness decreases, this stagnation zone expands and occupies the entire volume of the middle liquid. These counterintuitive results await their theoretical explanation and formulation of new contact conditions at the LM and MU interfaces.</p>","PeriodicalId":627,"journal":{"name":"Journal of Engineering Thermophysics","volume":"34 1","pages":"54 - 61"},"PeriodicalIF":1.3,"publicationDate":"2025-04-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143848966","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Effect of Light Gas Injection on the Weakly Accelerated Xenon Flow","authors":"A. Yu. Sakhnov,&nbsp;V. S. Naumkin","doi":"10.1134/S1810232825010102","DOIUrl":"10.1134/S1810232825010102","url":null,"abstract":"<p>The paper presents a numerical modeling of boundary layer equations supplemented with the <span>(k)</span>-<span>(omega)</span>-<span>(gamma)</span> turbulence model, that describe an accelerated xenon flow at the helium injection through the wall. Authors set values of the acceleration parameter <span>(K)</span> of <span>(4cdot10^{-7})</span> and the injection parameter <span>(overline{j_{w}})</span> in the range from <span>(10^{-4})</span> to <span>(10^{-3})</span>. The problem was solved by the finite difference approach with the implicit scheme. The study showed that the helium as a light gas injection into the accelerated xenon flow may results to the occurrence of the local flow laminarization near the wall together with turbulent flow in the outer part of the boundary layer. It was shown that the increase of the injected gas temperature leads to the increase of the skin-friction in two times under considered conditions. At that, the thermal and mass Stanton numbers increase by no more than 20% relatively the flow with the quasi-isothermal light gas injection.</p>","PeriodicalId":627,"journal":{"name":"Journal of Engineering Thermophysics","volume":"34 1","pages":"107 - 120"},"PeriodicalIF":1.3,"publicationDate":"2025-04-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143848921","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Correcting Spectral Density of Laser Doppler Anemometer Signals during Measuring of High-Speed Aerodynamic Flows. Part 1","authors":"V. V. Rakhmanov,&nbsp;I. K. Kabardin,&nbsp;A. V. Klimov,&nbsp;V. G. Glavny,&nbsp;D. V. Kulikov,&nbsp;V. G. Meledin,&nbsp;S. V. Dvoynishnikov,&nbsp;V. O. Zuev,&nbsp;G. V. Bakakin,&nbsp;V. A. Pavlov","doi":"10.1134/S1810232825010023","DOIUrl":"10.1134/S1810232825010023","url":null,"abstract":"<p>The first part of the work sets out the problem for a method of constructing correction coefficients to compensate for distortions introduced by the non-uniform frequency characteristics of the electronic path of a laser Doppler velocimeter into the spectral density of Doppler signals. The method relies on averaging a statistical ensemble of the spectral densities of noise signals obtained during illumination of a photodetector by a white light source, constructing the inverse function to the averaged spectral density acquired with truncation in the low- and high- frequency bands, and applying digital low-pass filtering to it. A model numerical experiment has been carried out. The results of the experiment are presented, and they confirm increase in the velocity measurement error as the flow rate grows.</p>","PeriodicalId":627,"journal":{"name":"Journal of Engineering Thermophysics","volume":"34 1","pages":"12 - 24"},"PeriodicalIF":1.3,"publicationDate":"2025-04-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143848963","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Using LED Interferometry Technique to Study Pressure Reduction Effect on Microlayer Thickness during Pool Boiling","authors":"V. Serdyukov,&nbsp;I. Kosovskikh,&nbsp;I. Malakhov","doi":"10.1134/S1810232825010011","DOIUrl":"10.1134/S1810232825010011","url":null,"abstract":"","PeriodicalId":627,"journal":{"name":"Journal of Engineering Thermophysics","volume":"34 1","pages":"1 - 11"},"PeriodicalIF":1.3,"publicationDate":"2025-04-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143848962","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Heat Transfer Increase Research According to Using Different Combined Jet Flow Channel Design and Nanofluids","authors":"Y. Alnak","doi":"10.1134/S1810232825010151","DOIUrl":"10.1134/S1810232825010151","url":null,"abstract":"<p>This study focused on the numerical investigation of heat transfer from various shaped copper plate surfaces exposed to a constant heat flux of 1000 W/m². The analysis employed a combination of cross-flow and impinging jet flows. The numerical simulations were carried out by solving the energy and Navier–Stokes equations using the Ansys–Fluent computer program with the <span>(k)</span>-<span>(varepsilon)</span> turbulence model. To guide the combined jet flow towards the heated surfaces in the channel, horizontal fins with 30° and 60° angles were placed in the channel. The channel height (<span>(H)</span>) was set at 4 times the diameter (<span>(D)</span>), and the fin distance from the jet inlet (<span>(N)</span>) was equal to <span>(D)</span>. Different fin lengths of <span>(D)</span>, <span>(1.166D)</span>, and <span>(1.333D)</span> (K) were utilized in the channels. The study considered three types of fluids: water, 2% CuO-Water, and 0.02% GO-Water nanofluids. The upper and lower surfaces of the channel and the fin were assumed to be adiabatic, and the Reynolds number of the flow ranged from 5000 to 15000. The results of this work were compared with experimental studies from the literature, and good agreement was found between them. Unlike previous studies, this research explored the effects of fin lengths and fin angles on heat transfer from differently shaped surfaces and the flow structures created by the fins in the channels, using GO-Water and CuO-Water nanofluids. The results were presented in terms of the mean Nusselt number variations for each model surface. Additionally, velocity and temperature contour distributions of the combined jet flow along the channel for CuO-Water nanofluid were analyzed. Performance Evaluation Coefficient (PEC) values, along with average Nusselt number (Nu<span>(_{m}))</span> and surface temperature (<span>(T_{m}))</span> values, were assessed at different Reynolds numbers for all three patterned surfaces in the channels. At Re = 5000 and <span>(K=D)</span>, there were significant increases in Nu<span>(_{m})</span> values for cube, roofed, and square hollow model surfaces when using a 60° fin and GO-Water nanofluid compared to channels with water flow and no fins.</p>","PeriodicalId":627,"journal":{"name":"Journal of Engineering Thermophysics","volume":"34 1","pages":"180 - 207"},"PeriodicalIF":1.3,"publicationDate":"2025-04-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143848926","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Pressure Drop Calculation at Flow Boiling in a Minichannel for a Wide Range of Reduced Pressures","authors":"A. V. Belyaev,&nbsp;N. E. Sidelnikov,&nbsp;E. I. Gareev,&nbsp;A. V. Dedov","doi":"10.1134/S1810232824040040","DOIUrl":"10.1134/S1810232824040040","url":null,"abstract":"<p>This paper studies the validity of prediction tools for two-phase flow pressure drops in wide range of reduced pressures based on the comparison between new experimental results and theoretical results predicted with the commonly used methods. The original dataset was obtained in a vertical uniformly heated minichannel 1.1 mm inner diameter with R125 and RC318 as working fluids. Uniform heating was carried out by electric current, simulating real flow conditions in heat exchangers, which is a distinctive feature of this work from most similar studies. The mass velocity varied in the range from 200 to 1400 kg/(m²s), the reduced pressure varied from 0.132 to 0.70, the heat flux density range was from 4 to 322 kW/m², the inlet vapor quality was set from −0.2 to −0.06 and outlet vapor quality reached 1 at minimum flow rates. The database is composed of 115 data points of two-phase flow boiling and was compared against well-known two-phase pressure drop prediction methods. The effect of the reduced pressure on the ability of the methods to predict the pressure drop was pointed out.</p>","PeriodicalId":627,"journal":{"name":"Journal of Engineering Thermophysics","volume":"33 4","pages":"706 - 721"},"PeriodicalIF":1.3,"publicationDate":"2025-01-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142995400","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Heat Transfer during Condensation of Liquid Vapor on Horizontal Circular Tube in Hydrophobic Granular Layer","authors":"M. I. Shilyaev,&nbsp;E. M. Khromova,&nbsp;A. R. Bogomolov","doi":"10.1134/S1810232824040143","DOIUrl":"10.1134/S1810232824040143","url":null,"abstract":"<p>Analytical modeling of heat transfer during condensation onto a horizontal round tube placed in a hydrophobic granular layer has been performed. According to generalized experimental results of the authors, the area under study was divided into three regimes of the condensate film flow: Re <span>(&lt; 5)</span>, <span>(5 &lt; {rm Re} &lt; 10)</span>, and Re <span>(&gt; 10)</span>. For the first two regimes, in the absence of effect of capillary forces, theoretical solutions were found based on the representation of a near-wall pore channel in the form of a flat annular slot with hydrophobic side surfaces; the solutions are in good agreement with the experimental data. At Re <span>(&gt; 10)</span>, a self-similar regime of the hydrodynamics of the condensate film settles, independent of the Re number, with a constant mean film thickness over the tube perimeter and the condensate part not involved in the heat transfer in the tube draining into the pore space of the layer. In all analyzed cases, there is heat transfer deterioration by two to three times on a horizontal tube in a hydrophobic layer in comparison with a smooth hydrophilic tube, because of the peculiarities of the hydrodynamics of the condensate flow in the wall pore channels. For all modes, formulas were obtained for calculation of the Nusselt numbers of heat transfer in dependence on the Re number.</p>","PeriodicalId":627,"journal":{"name":"Journal of Engineering Thermophysics","volume":"33 4","pages":"840 - 851"},"PeriodicalIF":1.3,"publicationDate":"2025-01-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142995446","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Experimental Research on Combined Methods against Icing of Wind Turbine Blades","authors":"V. G. Meledin,&nbsp;I. K. Kabardin,&nbsp;S. V. Dvoynishnikov,&nbsp;V. O. Zuev,&nbsp;O. G. Mukhin,&nbsp;S. V. Kakaulin,&nbsp;M. R. Gordienko,&nbsp;K. S. Zubanov,&nbsp;K. I. Stepanov,&nbsp;N. S. Goltsev,&nbsp;E. M. Tolstopyatov,&nbsp;P. N. Grakovich,&nbsp;L. F. Ivanov,&nbsp;D. V. Brel,&nbsp;L. A. Kalinin","doi":"10.1134/S181023282404009X","DOIUrl":"10.1134/S181023282404009X","url":null,"abstract":"<p>The dynamic development and enhancement of the efficiency and safety of power engineering in the Arctic and remote Siberian regions of Russia are promising and relevant. The aim of this work is search for scientifically based approaches and methods against icing, which is one of the main problems hindering efficient use of wind turbines for autonomous power supply to remote settlements in the Far North. The necessity in the research and its relevance are confirmed by the growing interest in the development of the Arctic region by the leading world countries. The presented research strives for an optimal strategy against icing of wind turbine blades in climatic conditions typical of the Arctic coast of Russia. The efficiency of combined anti-icing methods relying on the use of aerodynamically transparent substrates, hierarchical superhydrophobic (HSH) coatings, and materials based on polytetrafluoroethylene fiber for wind turbine blades in Arctic climatic conditions was experimentally studied. It is a fundamentally new approach, which has no world analogues. For verification of the efficiency of the de-icing systems and identification of the most efficient protection methods or combination of them, an experimental comparison was made for the efficiency of superhydrophobic coatings when used separately and together with various traditional de-icing methods based on heaters and ultrasonic and vibration devices. It has been shown that the integral use of the proposed methods and approaches successfully solves the problem of developing a general anti-icing strategy.</p>","PeriodicalId":627,"journal":{"name":"Journal of Engineering Thermophysics","volume":"33 4","pages":"779 - 791"},"PeriodicalIF":1.3,"publicationDate":"2025-01-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142995398","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}