Heat and Mass Transfer in Turbulent Boundary Layers

Leont'ev, A. I.

doi:10.1016/s0065-2717(08)70050-9

Cited by 13 publications

(9 citation statements)

References 43 publications

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“…In Fig. 6, the present results are compared to correlations for the film cooling effectiveness in the near-slot region from Lefebvre (1972, 1973), who summarized results from Stollery and El-Ehwany (1965), Leont'ev (1966), Whitelaw (1967) and Bradbury (1967). In case of the blowing ratios M = 1.6 and M = 3.39, the present results agree excellent with Ballal's and Lefebvre's correlation.…”

Section: Film Cooling Effectivenesssupporting

confidence: 77%

Film Cooling Effectiveness and Heat Transfer Coefficients for Slot Injection at High Blowing Ratios

Bittlinger

Schulz

Wittig

1994

Volume 4: Heat Transfer; Electric Power; Industrial and Cogeneration

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In continuation of earlier studies comparing heat transfer results for flow over a backward facing step and a jet in crossflow, a comprehensive data base for slot film cooling is presented. Specifically, heat transfer measurements adjacent to the injection slot for high blowing ratios were of interest. The heat transfer distributions for these conditions are of increasing significance in modern combustor liners. The new data base includes velocity and temperature profile measurements, adiabatic wall temperature and heat transfer measurements and will serve as a data base for testing newly developed numerical models. t = lip thickness see Eq. 6 i = inflow Presented at the International Gas Turbine and Aeroengine Congress and Exposition

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Section: Film Cooling Effectivenesssupporting

confidence: 77%

Film Cooling Effectiveness and Heat Transfer Coefficients for Slot Injection at High Blowing Ratios

Bittlinger

Schulz

Wittig

1994

Volume 4: Heat Transfer; Electric Power; Industrial and Cogeneration

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“…Температурное поле гильзы цилиндров [3] назначали согласно экс-периментальным данным, полученным в режи-ме номинальной мощности двигателя. Допол-нительно задавали значения коэффициентов теплоотдачи и температуры охлаждающей жидкости в полостях моноблока [4,5]. Послед-нюю на входе в дизель принимали равной 60 °С, а на выходе из него -80 °С как максимально допустимую температуру [6,7].…”

Section: таблицаunclassified

“…5, где желтым цветом обозначены граничные Рис. 5 Данный характер деформации обусловлен тем, что моноблок нагрет неравномерно, так как со стороны выпуска температура значительно выше, чем со стороны впуска, это ведет к более интенсивному расширению материала с более нагретой стороны и, как следствие, к изгибу.…”

Section: рис 2 конечно-элементная модель моноблокаunclassified

The Calculation of the Thermal and Stress-Strain State for the Monoblock of a High-Speed Marine Diesel Engine

Chainov¹,

Иванова²,

Мелещенко³

2017

PoHEI.MB

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Рассмотрен быстроходный судовой дизельный двигатель 42ЧН16/17, обеспечиваю-щий мощность 2 940 кВт при частоте вращения коленчатого вала 2 200 мин -1 . Осо-бенностью дизеля является моноблочная конструкция корпуса, выполненного из алюминиевого сплава АЛ4 с установленными внутри тонкостенными гильзами ци-линдров, значительная овализация которых приводит к увеличению расхода смазоч-ного масла и снижению ресурса двигателя. Проведены исследования по уменьшению тепловой напряженности узла моноблок-гильза цилиндра, а также поиск альтерна-тивных конструкторских решений в этом направлении. С применением численного анализа на базе объемных конечно-элементных моделей изучены поля температур, перемещений, деформаций, напряжений корпусных деталей дизеля и намечены пути целесообразного снижения в первую очередь их деформаций.Ключевые слова: узел моноблок-цилиндр, овальность гильзы цилиндра, перемеще-ния узлов, температурное поле моноблока, температурное поле гильзы, метод конеч-ных элементов This article examines a high-speed marine diesel engine 42ChN16/17 that provides 2940 kW of power at the crankshaft rotational frequency of 2 200 min -1 . The diesel engine features a monoblock case made of the AL4 aluminium alloy, with thin-walled cylinder liners whose considerable out-of-roundness leads to an increase in lubricant consumption and a reduction in engine life. A study aimed at decreasing the thermal stress state of the monoblock-cylinder unit is conducted as well as a search for alternative design solutions to support this. A numerical analysis based on the finite element method is performed to study fields of temperatures, displacements, deformations and stresses of the engine case parts. Ways to decrease, first and foremost, deformations of the parts are outlined.Keywords: monoblock-cylinder unit, cylinder liner out-of-roundness, displacement of units, monoblock temperature field, liner temperature field, finite element method

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“…ii'ir eli- Under stationary conditions a gas mass flow rate with the temperature T can be established through the porous disc (Afgan and Leontiev, 1994), (Martins et a], 1994). It is known, (Hartnet and Eckert, 1957), (Kutateladze and Leontiev, 1964) and (Leontiev, 1966) that at a specific gas mass flow rate through the filament, the boundary layer of the gas flowing over the porous filament is blownoff, resulting in the convective heat transfer at the surface to become practically equal to zero. In the case of an external flow over a porous surface with a laminar boundary layer developing over it, the critical value of the blow-off parameter is j.,o Reg = C…”

Section: Basic Principlementioning

confidence: 99%

“…For the case of a turbulent boundary layer, the direction of the flow relatively to the porous surface is not important, but a more complex expression is required to determine the critical blow-off gas (BOG) mass flow rate as a function of the external flow characteristics. A detailed discussion on this topic can be found at reference (Leontiev, 1966). A synthesis of this whole theory, focus on the present application can be found at (Martins et al, 1998b).…”

Section: Basic Principlementioning

confidence: 99%

Radiation and Convection Heat Flux Sensor for High Temperature Gas Environment

Martins¹,

Carvalho²,

Afgan³

et al. 1998

Volume 5: Manufacturing Materials and Metallurgy; Ceramics; Structures and Dynamics; Controls, Diagnostics and Instrumentation;

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The heat flux measurement is one of the essential parameter for the diagnostic of thermal systems. In the high temperature environment there are difficulties in differentiating between the convective and radiation component of heat flux on the heat transfer surface. A new method for heat flux measurement is being developed using a porous sensing element. The gas stream flowing through the porous element is used to measure the heat received by the sensor surface exposed to the hot gas environment and to control whether or not the sensing element receives the convection component of the total heat flux. It is possible to define a critical mass flow rate corresponding to the destruction of the boundary layer over the sensing element. With subcritical mass flow rate the porous sensing element will receive both the convective and radiative heat fluxes. A supercritical mass flow rate will eliminate the convective component of the total heat flux. Two consecutive measurements considering respectively a critical and a sub-critical mass flow rate can be used to determine separately the convection and radiation heat fluxes. A numerical model of sensor with appropriate boundary condition has been developed in order to perform analysis of possible options in the design of the sensor. The analysis includes: geometry of element, physical parameters of gas and solid and gas flow rate through the porous element. For the optimal selection of the relevant parameters an experimental set-up was designed, including the sensor element with corresponding cooling and monitoring system and high temperature radiation source. Applying the respective measuring procedure the calibration curve of the sensor was obtained. The linear dependency of the heat flux and respective temperature difference of the gas was verified. The accuracy analysis of the sensor reading has proved high linearity of the calibration curve and accuracy of ± 5%.

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Heat and Mass Transfer in Turbulent Boundary Layers

Cited by 13 publications

References 43 publications

Film Cooling Effectiveness and Heat Transfer Coefficients for Slot Injection at High Blowing Ratios

Film Cooling Effectiveness and Heat Transfer Coefficients for Slot Injection at High Blowing Ratios

The Calculation of the Thermal and Stress-Strain State for the Monoblock of a High-Speed Marine Diesel Engine

Radiation and Convection Heat Flux Sensor for High Temperature Gas Environment

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