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Toshiaki Setoguchi - One of the best experts on this subject based on the ideXlab platform.
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Characteristics of Supersonic Impinging Moist Air Jets
International Journal of Turbo & Jet-engines, 2020Co-Authors: Miah Md Ashraful Alam, Shigeru Matsuo, Toshiaki Setoguchi, Shen YuAbstract:Supersonic impinging Jets, such as those occurring in the space launch vehicle systems, multi-stage rocket separation, jet-engine exhaust impingement, terrestrial rocket launch, and in the next generation short take off and vertical landing (STOL) Aircraft, generate a highly oscillatory flow with very high unsteady loads on the near by structures and the landing surfaces. These high-pressure and acoustic loads are also accompanied by a dramatic loss in lift during Aircraft hover. Previous studies of supersonic impinging jets suggest that the highly unsteady behavior of the impinging jets is due to a feedback loop between the fluid And acoustic fields, which leads to these adverse effects, In actual supersonic jet flow, usually the working gas nu be condensable gas such as steam or Moist Air. In these cases, the non-equilibrium condensation may occur in the region between nozzle exit and an object. The jet flow with non-equilibrium condensation may be quite different from that without condensation, In the present study, characteristics of under-expanded axisymmetric supersonic impinging Moist Air jets on a vertical flat plate were investigated numerically.
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Effect of condensing Moist Air on unsteady shock waves around a symmetric disk in transonic internal flows
Aerospace Science and Technology, 2013Co-Authors: A. B. M. Toufique Hasan, Shigeru Matsuo, Toshiaki Setoguchi, Tokitada HashimotoAbstract:Abstract Shock waves are often observed around a symmetric disk in transonic or supersonic internal flow fields. In these cases, shock wave-boundary layer interaction becomes complex and induces the unsteady self-excited shock oscillations in the flow field. However, when water vapor is contained in the main flow, rapid expansion of the flow may give rise to non-equilibrium condensation of Moist Air. In the present study, the effect of condensing Moist Air flows on unsteady behavior of shock waves around a symmetric disk is studied numerically. The flow fields were investigated at two pressure ratios (total back pressure to total reservoir pressure) of 0.739 and 0.500. Results showed that in the absence of non-equilibrium condensation, the shock wave oscillates alternatively between the upper and lower disk surfaces at the pressure ratio of 0.739 and in the wake region at 0.500. However, in the presence of non-equilibrium condensation, the flow field aerodynamic instabilities such as root mean square of pressure oscillation and shock induced oscillations frequencies were reduced significantly compared with those in the absence of non-equilibrium condensation. In addition, the total pressure loss increased and wake frequency was reduced in case with condensing Moist Air flows.
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effects of condensing Moist Air on shock induced oscillation around an Airfoil in transonic internal flows
International Journal of Mechanical Sciences, 2012Co-Authors: A Toufique B M Hasan, Shigeru Matsuo, Toshiaki Setoguchi, A Sadrul K M IslamAbstract:Abstract Shock induced oscillation around an Airfoil in transonic internal flow fields are often observed due to complex shock wave boundary layer interaction. However, in actual flow where finite amount of water vapor is present in the Air, the rapid expansion of the flow may give rise to non-equilibrium condensation. Effects of condensing Moist Air on unsteady shock induced oscillation were numerically studied for total back pressure to reservoir pressure ratios of 0.73–0.65. Results showed that in case with condensing Moist Air flows, the root mean square of shock induced pressure oscillation and the oscillation frequency were reduced significantly compared with those without the non-equilibrium condensation. However, there was an increase of total pressure loss for condensing Moist Air flows.
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Shock wave in supersonic Moist Air jet for a low pressure ratio
Journal of Thermal Science, 2011Co-Authors: Yumiko Otobe, Hideo Kashimura, Toshiaki SetoguchiAbstract:In the present study, a computational fluid dynamics work was performed to investigate the occurrence of the shock wave by condensation in supersonic Moist Air jet. The unsteady, compressible axisymmetric Navier-Stokes equation is solved by TVD(Total Variation Diminishing) scheme in this study. The numerical simulations have been performed for low pressure ratio and various humidities. The results show the occurrence of the shock wave in supersonic Moist Air jet for a low pressure ratio when Mach disk does not occur, depending on humidity of the Air.
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Supersonic Moist Air jet impingements on flat surface
Journal of Thermal Science, 2010Co-Authors: Miah Md Ashraful Alam, Shigeru Matsuo, Toshiaki SetoguchiAbstract:Pronounced aeroacoustic resonances are exhibited in the flowfield where a jet emerges from an orifice or a nozzle and impinges on a solid surface. One instance where such resonances are produced is in a high speed jet impingement, such as in the space launch vehicle systems, jet-engine exhaust impingement, and in the short take-off and vertical landing (STOVL) Aircraft, etc. A highly unsteady flowfield leading to a drastic increase of noise level with very high dynamic pressure and thermal loads are noticed on nearby surfaces results dramatic lift loss, severe ground erosion and hot gas ingestion to the inlet in the jet engines. This highly unsteady behavior of the impinging jets is due to a feedback loop between the fluid and acoustic fields. In actual jet flow, the working gas may contain condensable gas such as steam or Moist Air. In these cases, the non-equilibrium condensation may occur at the region between nozzle exit and an object. The jet flow with non-equilibrium condensation may be quite different from that without condensation. Therefore, in this study, the effect of the non-equilibrium condensation of Moist Air on the axisymmetric under-expanded supersonic impinging jet on a vertical flat plate was investigated numerically.
Pascal Marquet - One of the best experts on this subject based on the ideXlab platform.
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definition of the Moist Air exergy norm a comparison with existing Moist energy norms
arXiv: Atmospheric and Oceanic Physics, 2019Co-Authors: Pascal Marquet, Jeanfrancois Mahfouf, Daniel HoldawayAbstract:This study presents a new formulation for the norms and scalar products used in tangent linear or adjoint models to determine forecast errors and sensitivity to observations and to calculate singular vectors. The new norm is derived from the concept of Moist-Air available enthalpy, which is one of the availability functions referred to as exergy in general thermodynamics. It is shown that the sum of the kinetic energy and the Moist-Air available enthalpy can be used to define a new Moist-Air squared norm which is quadratic in: 1) wind components; 2) temperature; 3) surface pressure; and 4) water vapor content. Preliminary numerical applications are performed to show that the new weighting factors for temperature and water vapor are significantly different from those used in observation impact studies, and are in better agreement with observed analysis increments. These numerical applications confirm that the weighting factors for water vapor and temperature exhibit a large increase with height (by several orders of magnitude) and a minimum in the middle troposphere, respectively.
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The first and second order approximations of the third-law Moist-Air entropy potential temperature
arXiv: Atmospheric and Oceanic Physics, 2019Co-Authors: Pascal MarquetAbstract:It is important to be able to calculate the Moist-Air entropy of the atmosphere with precision. A potential temperature has already been defined from the third law of thermodynamics for this purpose. However, a doubt remains as to whether this entropy potential temperature can be represented with simple but accurate first- or second-order approximate formulas. These approximations are rigorously defined in this paper using mathematical arguments and numerical adjustments to some datasets. The differentials of these approximations lead to simple but accurate formulations for tendencies, gradients and turbulent fluxes of the Moist-Air entropy. Several physical consequences based on these approximations are described and can serve to better understand Moist-Air processes (like turbulence or diabatic forcing) or properties of certain Moist-Air quantities (like the static energies).
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Definition of the Moist-Air available enthalpy (exergy) norm: a comparison with existing "Moist energy norms"
arXiv: Atmospheric and Oceanic Physics, 2018Co-Authors: Pascal Marquet, Jeanfrancois Mahfouf, Daniel HoldawayAbstract:This study presents a new formulation for the norms and the scalar products used in tangent linear or adjoint models to determine forecast errors, sensitivity to observations or to calculate singular vectors. The new norm is derived from the concept of Moist-Air available enthalpy, which is one of the availability functions called exergy in general thermodynamics. It is shown that the sum of the kinetic energy and the Moist-Air available enthalpy can be used to define a new Moist-Air norm which is quadratic in: 1) wind components; 2) temperature; 3) surface pressure; and 4) water vapour content. Preliminary numerical applications are performed to show that the new weighting factors for temperature and water vapour are significantly different from those used in observation impact studies, and are in better agreement with observed analysis increments.
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The mixed-phase version of Moist-Air entropy
arXiv: Atmospheric and Oceanic Physics, 2016Co-Authors: Pascal MarquetAbstract:The aim of this note is to derive the mixed-phase version of the Moist-Air entropy potential temperature $\theta_s$ derived in Marquet (2011). This mixed-phase version is suitable to describe parcels where liquid water and ice are allowed to coexist, with possible under- or super-saturations, with possible supercooled water and with possible different temperatures for dry Air and water vapour, on the one hand, condensed water and ice, on the other hand. The impact of this new mixed-phase version for $\theta_s$ are evaluated by using high latitudes, SHEBA/FIRE-ACE vertical profiles depicted in Figure 7 of Morisson et al. (2011).
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An improved approximation for the Moist-Air entropy potential temperature $\theta_s$
arXiv: Atmospheric and Oceanic Physics, 2015Co-Authors: Pascal MarquetAbstract:The Moist-Air entropy is defined in Marquet (QJRMS 2011, arXiv:1401.1097) by $\boxed{s = s_{ref} + c_{pd} \: \ln(\theta_{s})}$ in terms of two constant values ($s_{ref}$, $c_{pd}$) and a potential entropy temperature denoted by $\theta_s$. It is shown in Marquet (2011) that a quantity denoted by $({\theta}_{s})_1$ plays the role of a leading order approximation of ${\theta}_{s}$. The aim of this note is to demonstrate in a more rigorous way that $({\theta}_{s})_1$ is indeed the leading order approximation of ${\theta}_{s}$, and to derive a second order approximation which may be used in computations of values, gradients or turbulent fluxes of Moist-Air entropy. Some impacts of this second order approximation are described in this brief version of a note to be submitted to the QJRMS.
Shigeru Matsuo - One of the best experts on this subject based on the ideXlab platform.
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Characteristics of Supersonic Impinging Moist Air Jets
International Journal of Turbo & Jet-engines, 2020Co-Authors: Miah Md Ashraful Alam, Shigeru Matsuo, Toshiaki Setoguchi, Shen YuAbstract:Supersonic impinging Jets, such as those occurring in the space launch vehicle systems, multi-stage rocket separation, jet-engine exhaust impingement, terrestrial rocket launch, and in the next generation short take off and vertical landing (STOL) Aircraft, generate a highly oscillatory flow with very high unsteady loads on the near by structures and the landing surfaces. These high-pressure and acoustic loads are also accompanied by a dramatic loss in lift during Aircraft hover. Previous studies of supersonic impinging jets suggest that the highly unsteady behavior of the impinging jets is due to a feedback loop between the fluid And acoustic fields, which leads to these adverse effects, In actual supersonic jet flow, usually the working gas nu be condensable gas such as steam or Moist Air. In these cases, the non-equilibrium condensation may occur in the region between nozzle exit and an object. The jet flow with non-equilibrium condensation may be quite different from that without condensation, In the present study, characteristics of under-expanded axisymmetric supersonic impinging Moist Air jets on a vertical flat plate were investigated numerically.
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Effect of condensing Moist Air on unsteady shock waves around a symmetric disk in transonic internal flows
Aerospace Science and Technology, 2013Co-Authors: A. B. M. Toufique Hasan, Shigeru Matsuo, Toshiaki Setoguchi, Tokitada HashimotoAbstract:Abstract Shock waves are often observed around a symmetric disk in transonic or supersonic internal flow fields. In these cases, shock wave-boundary layer interaction becomes complex and induces the unsteady self-excited shock oscillations in the flow field. However, when water vapor is contained in the main flow, rapid expansion of the flow may give rise to non-equilibrium condensation of Moist Air. In the present study, the effect of condensing Moist Air flows on unsteady behavior of shock waves around a symmetric disk is studied numerically. The flow fields were investigated at two pressure ratios (total back pressure to total reservoir pressure) of 0.739 and 0.500. Results showed that in the absence of non-equilibrium condensation, the shock wave oscillates alternatively between the upper and lower disk surfaces at the pressure ratio of 0.739 and in the wake region at 0.500. However, in the presence of non-equilibrium condensation, the flow field aerodynamic instabilities such as root mean square of pressure oscillation and shock induced oscillations frequencies were reduced significantly compared with those in the absence of non-equilibrium condensation. In addition, the total pressure loss increased and wake frequency was reduced in case with condensing Moist Air flows.
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effects of condensing Moist Air on shock induced oscillation around an Airfoil in transonic internal flows
International Journal of Mechanical Sciences, 2012Co-Authors: A Toufique B M Hasan, Shigeru Matsuo, Toshiaki Setoguchi, A Sadrul K M IslamAbstract:Abstract Shock induced oscillation around an Airfoil in transonic internal flow fields are often observed due to complex shock wave boundary layer interaction. However, in actual flow where finite amount of water vapor is present in the Air, the rapid expansion of the flow may give rise to non-equilibrium condensation. Effects of condensing Moist Air on unsteady shock induced oscillation were numerically studied for total back pressure to reservoir pressure ratios of 0.73–0.65. Results showed that in case with condensing Moist Air flows, the root mean square of shock induced pressure oscillation and the oscillation frequency were reduced significantly compared with those without the non-equilibrium condensation. However, there was an increase of total pressure loss for condensing Moist Air flows.
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Supersonic Moist Air jet impingements on flat surface
Journal of Thermal Science, 2010Co-Authors: Miah Md Ashraful Alam, Shigeru Matsuo, Toshiaki SetoguchiAbstract:Pronounced aeroacoustic resonances are exhibited in the flowfield where a jet emerges from an orifice or a nozzle and impinges on a solid surface. One instance where such resonances are produced is in a high speed jet impingement, such as in the space launch vehicle systems, jet-engine exhaust impingement, and in the short take-off and vertical landing (STOVL) Aircraft, etc. A highly unsteady flowfield leading to a drastic increase of noise level with very high dynamic pressure and thermal loads are noticed on nearby surfaces results dramatic lift loss, severe ground erosion and hot gas ingestion to the inlet in the jet engines. This highly unsteady behavior of the impinging jets is due to a feedback loop between the fluid and acoustic fields. In actual jet flow, the working gas may contain condensable gas such as steam or Moist Air. In these cases, the non-equilibrium condensation may occur at the region between nozzle exit and an object. The jet flow with non-equilibrium condensation may be quite different from that without condensation. Therefore, in this study, the effect of the non-equilibrium condensation of Moist Air on the axisymmetric under-expanded supersonic impinging jet on a vertical flat plate was investigated numerically.
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Hysteretic Phenomenon of Underexpanded Moist Air Jet
AIAA Journal, 2009Co-Authors: Yumiko Otobe, Hideo Kashimura, Shigeru Matsuo, Tsuyoshi Yasunobu, Toshiaki SetoguchiAbstract:Moist Air jets, corresponding to the range of moderately underexpanded to strongly underexpanded conditions, have been investigated with the help of computational fluid dynamics methods. The equations for nucleation rate and droplet growth are incorporated into the unsteady, compressible Navier-Stokes equations. A third-order total variation diminishing finite difference scheme with monotonic upstream schemes for conservation lows is employed to discretize the spatial derivatives of the governing equations. The experiment is performed to validate the computational predictions. The initial degree of supersaturation is changed to obtain different values of the relative humidity of Moist Air. The pressure ratio is changed to investigate the characteristic behavior of the jets generated during the transient processes of startup and shutdown. The results obtained show that underexpanded Air jet produced during the startup transient of jet behaves different from the shutdown transient process, leading to a hysteretic phenomenon of underexpanded jet. It is also known that the Moist Air jet reduces the hysteretic phenomenon compared with the dry Air jet, and that nonequilibrium condensation that occurs in the underexpanded Moist Air jet is responsible for these findings.
A Sadrul K M Islam - One of the best experts on this subject based on the ideXlab platform.
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effects of condensing Moist Air on shock induced oscillation around an Airfoil in transonic internal flows
International Journal of Mechanical Sciences, 2012Co-Authors: A Toufique B M Hasan, Shigeru Matsuo, Toshiaki Setoguchi, A Sadrul K M IslamAbstract:Abstract Shock induced oscillation around an Airfoil in transonic internal flow fields are often observed due to complex shock wave boundary layer interaction. However, in actual flow where finite amount of water vapor is present in the Air, the rapid expansion of the flow may give rise to non-equilibrium condensation. Effects of condensing Moist Air on unsteady shock induced oscillation were numerically studied for total back pressure to reservoir pressure ratios of 0.73–0.65. Results showed that in case with condensing Moist Air flows, the root mean square of shock induced pressure oscillation and the oscillation frequency were reduced significantly compared with those without the non-equilibrium condensation. However, there was an increase of total pressure loss for condensing Moist Air flows.
Takashi Furusawa - One of the best experts on this subject based on the ideXlab platform.
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Wetness Effect on Transonic Moist-Air Flow Through a Compressor Rotor
Volume 3: Fluid Machinery; Erosion Slurry Sedimentation; Experimental Multiscale and Numerical Methods for Multiphase Flows; Gas-Liquid Gas-Solid and , 2018Co-Authors: Shota Moriguchi, Hironori Miyazawa, Takashi Furusawa, Satoru YamamotoAbstract:In this study, we simulated Moist-Air flows through a 3-D transonic compressor rotor, NASA Rotor 37, to investigate the thermophysical effects of evaporation of water droplets on 3-D compressor aerodynamics. The obtained results indicated that the total pressure ratio increased in the Moist-Air cases when compared with dry-Air case as a result of the cooling due to evaporation. While the choking mass-flow rate is almost identical for the dry-Air case and the Moist-Air cases, the operating curve was shifted to nearly choked state in the Moist-Air cases. Besides this, unsteady flows were obtained at higher mass-flow rate in the Moist-Air cases when compared with the dry-Air case. As a result, a significant deterioration in the operation was observed in the Moist-Air cases. This is due to the rapid and significant evaporation of water droplets after the passage shock. A secondary flow streaming radially outside toward the tip through the separated region intensified and contributed to a formation of large blockage around the tip region.
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Effect of inlet wetness on transonic wet-steam and Moist-Air flows in turbomachinery
International Journal of Heat and Mass Transfer, 2018Co-Authors: Satoru Yamamoto, Hironori Miyazawa, Shinji Moriguchi, Takashi FurusawaAbstract:This study investigates the effect of inlet wetness on transonic wet-steam and Moist-Air flows through turbine and compressor cascade channels. We first simulated the transonic wet-steam flows through a Bakhtar's turbine cascade channel under wind-tunnel conditions with inlet wetness. We then predicted the effects of inlet wetness on the Moist-Air flows expected through an Aircraft engine and an industrial gas turbine. For this purpose, we simulated the transonic Moist-Air flows through a transonic compressor cascade channel while changing the inlet wetness conditions. In both wet-stream and Moist-Air flows, the inlet wetness was quite sensitive to the growth and evaporation rates of the water droplets, and greatly influenced the shock location. Our results for Moist-Air flows suggest that the temperature beyond the shock is effectively decreased by a large number density of smaller water droplets.
