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Dm Vogt - One of the best experts on this subject based on the ideXlab platform.
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Numerical Investigation of Boundary Layers in Wet Steam Nozzles
2017Co-Authors: Starzmann J, A. White, Hughes Fr, Grubel M, Dm VogtAbstract:Copyright © 2017 by ASME. Condensing Nozzle flows have been used extensively to validate wet steam models. Many test cases are available in the literature, and in the past, a range of numerical studies have dealt with this challenging task. It is usually assumed that the Nozzles provide a one- or two-dimensional flow with a fully turbulent boundary layer (BL). The present paper reviews these assumptions and investigates numerically the influence of boundary layers on dry and wet steam Nozzle expansions. For the Narrow Nozzle of Moses and Stein, it is shown that the pressure distribution is significantly affected by the additional blockage due to the side wall boundary layer. Comparison of laminar and turbulent flow predictions for this Nozzles suggests that laminar-turbulent transition only occurs after the throat. Other examples are the Binnie and Green Nozzle and the Moore et al. Nozzles for which it is known that sudden changes in wall curvature produce expansion and compression waves that interact with the boundary layers. The differences between two- and three-dimensional calculations for these cases and the influence of laminar and turbulent boundary layers are discussed. The present results reveal that boundary layer effects can have a considerable impact on the mean Nozzle flow and thus on the validation process of condensation models. In order to verify the accuracy of turbulence modeling, a test case that is not widely known internationally is included within the present study. This experimental work is remarkable because it includes boundary layer data as well as the usual pressure measurements along the Nozzle centerline. Predicted and measured boundary layer profiles are compared, and the effect of different turbulence models is discussed. Most of the numerical results are obtained with the in-house wet steam Reynolds-averaged Navier-Stokes (RANS) solver, Steamblock, but for the purpose of comparison, the commercial program ANSYS CFX is also used, providing a wider range of standard RANSbased turbulence models
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Numerical Investigation of Boundary Layers in Wet Steam Nozzles
2017Co-Authors: Starzmann J, A. White, Grubel M, Hughes Fr, Dm VogtAbstract:Condensing Nozzle flows have been used extensively to validate wet steam models. Many test cases are available in the literature, and in the past, a range of numerical studies have dealt with this challenging task. It is usually assumed that the Nozzles provide a one- or two-dimensional flow with a fully turbulent boundary layer (BL). The present paper reviews these assumptions and investigates numerically the influence of boundary layers on dry and wet steam Nozzle expansions. For the Narrow Nozzle of Moses and Stein, it is shown that the pressure distribution is significantly affected by the additional blockage due to the side wall boundary layer. Comparison of laminar and turbulent flow predictions for this Nozzles suggests that laminar-turbulent transition only occurs after the throat. Other examples are the Binnie and Green Nozzle and the Moore et al. Nozzles for which it is known that sudden changes in wall curvature produce expansion and compression waves that interact with the boundary layers. The differences between two- and three-dimensional calculations for these cases and the influence of laminar and turbulent boundary layers are discussed. The present results reveal that boundary layer effects can have a considerable impact on the mean Nozzle flow and thus on the validation process of condensation models. In order to verify the accuracy of turbulence modeling, a test case that is not widely known internationally is included within the present study. This experimental work is remarkable because it includes boundary layer data as well as the usual pressure measurements along the Nozzle centerline. Predicted and measured boundary layer profiles are compared, and the effect of different turbulence models is discussed. Most of the numerical results are obtained with the in-house wet steam Reynolds-averaged Navier-Stokes (RANS) solver, Steamblock, but for the purpose of comparison, the commercial program ANSYS CFX is also used, providing a wider range of standard RANSbased turbulence models
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Numerical investigation of boundary layers in wet steam Nozzles
ASME TurboExpo 2016, 2016Co-Authors: Starzmann J, A. White, Grubel M, Hughes Fr, Dm VogtAbstract:© Copyright 2016 by ASM.Condensing Nozzle flows have been used extensively to validat wet steam models. Many test cases are available in th literature and in the past a range of numerical studies have deal with this challenging task. It is usually assumed that the Nozzle provide a one-or two-dimensional flow with a fully turbulen boundary layer. The present paper reviews these assumption and investigates numerically the influence of boundary layers o dry and wet steam Nozzle expansions For the Narrow Nozzle of Moses and Stein it is shown that th pressure distribution is significantly affected by the additiona blockage due to the side wall boundary layer. Comparison o laminar and turbulent flow predictions for this Nozzles suggest that laminar-Turbulent transition only occurs after the throat Other examples are the Binnie Nozzle and the Moore Nozzles fo which it is known that sudden changes in wall curvature produc expansion and compression waves that interact with the boundar layers. The differences between two-and three-dimensiona calculations for these cases and the influence of laminar and turbulen boundary layers are discussed The present results reveal that boundary layer effects cahave a considerable impact on the mean Nozzle flow and thu on the validation process of condensation models. In order t verify the accuracy of turbulence modelling a test case that i not widely known internationally is included within the present
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Numerical Investigation of Boundary Layers in Wet Steam Nozzles
'Organisation for Economic Co-Operation and Development (OECD)', 2016Co-Authors: Starzmann Joerg, Grubel M, Hughes Fr, White Alexander, Dm VogtAbstract:Condensing Nozzle flows have been used extensively to validate wet steam models. Many test cases are available in the literature, and in the past, a range of numerical studies have dealt with this challenging task. It is usually assumed that the Nozzles provide a one- or two-dimensional flow with a fully turbulent boundary layer (BL). The present paper reviews these assumptions and investigates numerically the influence of boundary layers on dry and wet steam Nozzle expansions. For the Narrow Nozzle of Moses and Stein, it is shown that the pressure distribution is significantly affected by the additional blockage due to the side wall boundary layer. Comparison of laminar and turbulent flow predictions for this Nozzles suggests that laminar–turbulent transition only occurs after the throat. Other examples are the Binnie and Green Nozzle and the Moore et al. Nozzles for which it is known that sudden changes in wall curvature produce expansion and compression waves that interact with the boundary layers. The differences between two- and three-dimensional calculations for these cases and the influence of laminar and turbulent boundary layers are discussed. The present results reveal that boundary layer effects can have a considerable impact on the mean Nozzle flow and thus on the validation process of condensation models. In order to verify the accuracy of turbulence modeling, a test case that is not widely known internationally is included within the present study. This experimental work is remarkable because it includes boundary layer data as well as the usual pressure measurements along the Nozzle centerline. Predicted and measured boundary layer profiles are compared, and the effect of different turbulence models is discussed. Most of the numerical results are obtained with the in-house wet steam Reynolds-averaged Navier–Stokes (RANS) solver, Steamblock, but for the purpose of comparison, the commercial program ansys cfx is also used, providing a wider range of standard RANS-based turbulence models.Engineering and Physical Sciences Research CouncilThis is the author accepted manuscript. It is currently under an indefinite embargo pending publication by the American Society of Mechanical Engineers (ASME)
J S Nelson - One of the best experts on this subject based on the ideXlab platform.
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measurement of heat flux and heat transfer coefficient during continuous cryogen spray cooling for laser dermatologic surgery
IEEE Journal of Selected Topics in Quantum Electronics, 2001Co-Authors: Guillermo Aguilar, Wim Verkruysse, Boris Majaron, Lars O Svaasand, E J Lavernia, J S NelsonAbstract:Cryogen spray cooling (CSC) has been used for selective epidermal cooling of human skin during laser therapy of patients with port wine stain (PWS) birthmarks. Unfortunately, current commercial CSC devices do not provide optimal cooling selectivity and, therefore, provide insufficient epidermal protection for some PWS patients. To assist in the development of improved atomizing Nozzle designs, a reliable method to quantify the CSC heat flux is needed. We introduce a novel method to determine the heat flux (q/sub s/) and heat transfer coefficient (h) at the surface of a sprayed object, based on measurements of steady-state temperature gradients along a thin copper rod during continuous cryogen spraying. For an atomizing Nozzle of inner diameter d/sub N/ = 0.7 mm, we found that q/sub s/ varies from 15 to 130 W/cm/sup 2/ and h increases nonlinearly from 15000 to 35000 W/m/sup 2/.K in the explored range of surface temperatures (T/sub s/, from -32 to -7/spl deg/C). Values of q/sub s/ obtained with a wider diameter Nozzle (d/sub N/ = 1.4 mm) are approximately twice as large than those of the Narrow Nozzle. The corresponding values of h are significantly higher (32000-40000 W/m/sup 2/.K) and almost independent of T/sub s/ within the same temperature range. When combined with fast flashlamp photography (FFLP) of spray shapes and sprayed surfaces, the results demonstrate that the liquid cryogen layer, as deposited by finely atomized sprays from Narrower Nozzles, can significantly impair q/sub s/. In contrast, the higher-momentum impact of coarser sprays from wider Nozzles reduces the thickness of the liquid layer in the impact area and/or enhances convection within it, yielding a larger q/sub s/.
Lars O Svaasand - One of the best experts on this subject based on the ideXlab platform.
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measurement of heat flux and heat transfer coefficient during continuous cryogen spray cooling for laser dermatologic surgery
IEEE Journal of Selected Topics in Quantum Electronics, 2001Co-Authors: Guillermo Aguilar, Wim Verkruysse, Boris Majaron, Lars O Svaasand, E J Lavernia, J S NelsonAbstract:Cryogen spray cooling (CSC) has been used for selective epidermal cooling of human skin during laser therapy of patients with port wine stain (PWS) birthmarks. Unfortunately, current commercial CSC devices do not provide optimal cooling selectivity and, therefore, provide insufficient epidermal protection for some PWS patients. To assist in the development of improved atomizing Nozzle designs, a reliable method to quantify the CSC heat flux is needed. We introduce a novel method to determine the heat flux (q/sub s/) and heat transfer coefficient (h) at the surface of a sprayed object, based on measurements of steady-state temperature gradients along a thin copper rod during continuous cryogen spraying. For an atomizing Nozzle of inner diameter d/sub N/ = 0.7 mm, we found that q/sub s/ varies from 15 to 130 W/cm/sup 2/ and h increases nonlinearly from 15000 to 35000 W/m/sup 2/.K in the explored range of surface temperatures (T/sub s/, from -32 to -7/spl deg/C). Values of q/sub s/ obtained with a wider diameter Nozzle (d/sub N/ = 1.4 mm) are approximately twice as large than those of the Narrow Nozzle. The corresponding values of h are significantly higher (32000-40000 W/m/sup 2/.K) and almost independent of T/sub s/ within the same temperature range. When combined with fast flashlamp photography (FFLP) of spray shapes and sprayed surfaces, the results demonstrate that the liquid cryogen layer, as deposited by finely atomized sprays from Narrower Nozzles, can significantly impair q/sub s/. In contrast, the higher-momentum impact of coarser sprays from wider Nozzles reduces the thickness of the liquid layer in the impact area and/or enhances convection within it, yielding a larger q/sub s/.
P.k. Ghosh - One of the best experts on this subject based on the ideXlab platform.
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ultra Narrow gap welding of thick section of austenitic stainless steel to hsla steel
Journal of Materials Processing Technology, 2017Co-Authors: Ramkishor Anant, P.k. GhoshAbstract:Abstract A substantially Narrow GMAW torch Nozzle head has been designed that enables Narrowing down of weld groove up to a limit of just accommodating the Nozzle in it where the groove wall of thick section virtually acts as a side wall of the Nozzle head to produce a Narrowest possible butt welding. A model of shielding gas flow dynamics and its flow rate in case of employing newly developed GMAW Nozzle head has been studied at different projection angle of torch Nozzle inside the Narrow groove of butt joint by using ANSYS-CFX(14.5) software. The utility aspect of such a Narrow Nozzle head from the view point of smooth flow of shielding gas inside a close fitted ultra-Narrow weld groove has also been studied. The outcome of the analytical studies has been used to produce a defect free ultra-Narrow multi-pass weld by employing P-GMAW process with vertically placed electrode depositing single bead per layer in weld groove.
Starzmann J - One of the best experts on this subject based on the ideXlab platform.
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Numerical Investigation of Boundary Layers in Wet Steam Nozzles
2017Co-Authors: Starzmann J, A. White, Hughes Fr, Grubel M, Dm VogtAbstract:Copyright © 2017 by ASME. Condensing Nozzle flows have been used extensively to validate wet steam models. Many test cases are available in the literature, and in the past, a range of numerical studies have dealt with this challenging task. It is usually assumed that the Nozzles provide a one- or two-dimensional flow with a fully turbulent boundary layer (BL). The present paper reviews these assumptions and investigates numerically the influence of boundary layers on dry and wet steam Nozzle expansions. For the Narrow Nozzle of Moses and Stein, it is shown that the pressure distribution is significantly affected by the additional blockage due to the side wall boundary layer. Comparison of laminar and turbulent flow predictions for this Nozzles suggests that laminar-turbulent transition only occurs after the throat. Other examples are the Binnie and Green Nozzle and the Moore et al. Nozzles for which it is known that sudden changes in wall curvature produce expansion and compression waves that interact with the boundary layers. The differences between two- and three-dimensional calculations for these cases and the influence of laminar and turbulent boundary layers are discussed. The present results reveal that boundary layer effects can have a considerable impact on the mean Nozzle flow and thus on the validation process of condensation models. In order to verify the accuracy of turbulence modeling, a test case that is not widely known internationally is included within the present study. This experimental work is remarkable because it includes boundary layer data as well as the usual pressure measurements along the Nozzle centerline. Predicted and measured boundary layer profiles are compared, and the effect of different turbulence models is discussed. Most of the numerical results are obtained with the in-house wet steam Reynolds-averaged Navier-Stokes (RANS) solver, Steamblock, but for the purpose of comparison, the commercial program ANSYS CFX is also used, providing a wider range of standard RANSbased turbulence models
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Numerical Investigation of Boundary Layers in Wet Steam Nozzles
2017Co-Authors: Starzmann J, A. White, Grubel M, Hughes Fr, Dm VogtAbstract:Condensing Nozzle flows have been used extensively to validate wet steam models. Many test cases are available in the literature, and in the past, a range of numerical studies have dealt with this challenging task. It is usually assumed that the Nozzles provide a one- or two-dimensional flow with a fully turbulent boundary layer (BL). The present paper reviews these assumptions and investigates numerically the influence of boundary layers on dry and wet steam Nozzle expansions. For the Narrow Nozzle of Moses and Stein, it is shown that the pressure distribution is significantly affected by the additional blockage due to the side wall boundary layer. Comparison of laminar and turbulent flow predictions for this Nozzles suggests that laminar-turbulent transition only occurs after the throat. Other examples are the Binnie and Green Nozzle and the Moore et al. Nozzles for which it is known that sudden changes in wall curvature produce expansion and compression waves that interact with the boundary layers. The differences between two- and three-dimensional calculations for these cases and the influence of laminar and turbulent boundary layers are discussed. The present results reveal that boundary layer effects can have a considerable impact on the mean Nozzle flow and thus on the validation process of condensation models. In order to verify the accuracy of turbulence modeling, a test case that is not widely known internationally is included within the present study. This experimental work is remarkable because it includes boundary layer data as well as the usual pressure measurements along the Nozzle centerline. Predicted and measured boundary layer profiles are compared, and the effect of different turbulence models is discussed. Most of the numerical results are obtained with the in-house wet steam Reynolds-averaged Navier-Stokes (RANS) solver, Steamblock, but for the purpose of comparison, the commercial program ANSYS CFX is also used, providing a wider range of standard RANSbased turbulence models
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Numerical investigation of boundary layers in wet steam Nozzles
ASME TurboExpo 2016, 2016Co-Authors: Starzmann J, A. White, Grubel M, Hughes Fr, Dm VogtAbstract:© Copyright 2016 by ASM.Condensing Nozzle flows have been used extensively to validat wet steam models. Many test cases are available in th literature and in the past a range of numerical studies have deal with this challenging task. It is usually assumed that the Nozzle provide a one-or two-dimensional flow with a fully turbulen boundary layer. The present paper reviews these assumption and investigates numerically the influence of boundary layers o dry and wet steam Nozzle expansions For the Narrow Nozzle of Moses and Stein it is shown that th pressure distribution is significantly affected by the additiona blockage due to the side wall boundary layer. Comparison o laminar and turbulent flow predictions for this Nozzles suggest that laminar-Turbulent transition only occurs after the throat Other examples are the Binnie Nozzle and the Moore Nozzles fo which it is known that sudden changes in wall curvature produc expansion and compression waves that interact with the boundar layers. The differences between two-and three-dimensiona calculations for these cases and the influence of laminar and turbulen boundary layers are discussed The present results reveal that boundary layer effects cahave a considerable impact on the mean Nozzle flow and thu on the validation process of condensation models. In order t verify the accuracy of turbulence modelling a test case that i not widely known internationally is included within the present
