The Experts below are selected from a list of 360 Experts worldwide ranked by ideXlab platform

R Moradi - One of the best experts on this subject based on the ideXlab platform.

  • computational investigation of multi cavity fuel injection on hydrogen Mixing at supersonic combustion chamber
    International Journal of Hydrogen Energy, 2020
    Co-Authors: Tran Dinh Manh, Nguyen Dang Nam, R Moradi, Barzegar M Gerdroodbary, Houman Babazadeh
    Abstract:

    Abstract Enhancement of the Mixing inside the combustor is a significant process for increasing the efficiency of the scramjet. This work applied the computational method for the investigation of the depth of the cavity on the flow feature of the multi hydrogen jet in the supersonic crossflow. The main focus of this research is to evaluate the depth of the cavity on the Mixing Rate of the hydrogen jets inside the combustion chamber. CFD method with the SST turbulence technique is applied for the simulation of the fluid flow inside the domain. The impact of the depth of the cavity, the pressure of the fuel jet and the number of the jet are comprehensively explained in this study. Our findings show that the rising of the cavity enhances the Mixing inside the domain due to more fuel distribution along the spanwise direction. Our results clearly demonstRate that replacing the single jet with 8 equivalent multi jets increases the Mixing Rate of more than 45% in the vicinity of the jet injection. Attained results revealed that increasing the jet space develops the Mixing in far downstream. Obtained results also show that Mixing intensifies 15% when jet space of 8 microjets is increased from 4 dj to 10 dj.

  • the effect of sinusoidal wall on hydrogen jet Mixing Rate considering supersonic flow
    Energy, 2020
    Co-Authors: Tran Dinh Manh, Mostafa Barzegar Gerdroodbary, Nguyen Dang Nam, R Moradi, Houman Babazadeh
    Abstract:

    Abstract The efficiency of the scramjet is highly associated with the Rate of the Mixing through the combustion tank. In current article, simulation approach was used to inspect the effect of the sinusoidal wall on hydrogen Mixing cross-flow jet. The key focus of current paper is to exhibit the role of various sinusoidal profiles on the flow structure and streamline pattern of the mainstream and fuel jet. To simulate the flow feature, a 3D model was chosen and Navier-stocks equations were solved with energy and species mass transport equations to evaluate the Mixing Rate of hydrogen jet. Hydrogen gas is injected through the nozzle in the downstream of the sinusoidal wave. The impact of total jet pressure on the flow feature is exclusively studied. Also, the Mixing zones of the various models are compared. Attained results display that the appearance of the wavy wall augments the Mixing Rate when the frequency of the sinusoidal wave is high enough. Our findings also reveal that using extended surface has less effect in high pressure condition. The comparison of the Mixing Rate shows that the presence of sinusoidal wavy wall with frequency of 1200 increases the Mixing Rate more than 25% than simple flat surface.

  • the influence of the sinusoidal shock generator on the Mixing Rate of multi hydrogen jets at supersonic flow
    Aerospace Science and Technology, 2020
    Co-Authors: Barzegar M Gerdroodbary, R Moradi, Houman Babazadeh
    Abstract:

    Abstract The Rate of fuel Mixing inside the combustor is highly significant and effective on the performance of the scramjet engine. In this study, numerical simulations are applied to study the influence of the sinusoidal shock generator on the flow structure of the multi hydrogen jet at supersonic crossflow. The primary focus of this research is to perform flow analysis to determine the role of the shock interaction produced by the presence of the shock generator on the Rate of Mixing in the downstream of the fuel jets. To simulate the flow, the CFD method with the K-w turbulence model is applied to capture the shock formation inside the domain. According to our results, the Mixing Rate increases by approximately 40% as the amplitude of the sinusoidal shock generator increases from 2 to 5 mm. Besides, it is found that the fuel distribution becomes uniform when the produced shock generator is more strengthen.

  • the influence of upstream wavy surface on the Mixing zone of the transverse hydrogen jet at supersonic free stream
    Aerospace Science and Technology, 2019
    Co-Authors: Barzegar M Gerdroodbary, R Moradi, Iskander Tlili
    Abstract:

    Abstract In this study, the computational fluid dynamic is applied to investigate the impact of the upstream wavy surface on the Mixing Rate of the hydrogen fuel jet. The flow feature analyses are also performed to disclose the man influence of the upstream wavy surface on the Mixing zone and fuel penetration in the downstream of the jet. To simulate the jet interaction with supersonic free stream, Navier-Stokes equations are coupled with conservation equations of energy and species equation. Since the interaction of the transverse fuel jet with a supersonic mainstream is a complex, a three-dimensional model with high resolution is produced for our investigations. The impact of the supersonic Mach number on the efficiency of the fuel Mixing in the presence of the sinusoidal wavy surface. Comprehensive parametric studies are done to reveal the influence of the jet pressure and wavy profile on the Mixing performance in the downstream of the jet. According to obtained results, the Mixing Rate of the fuel in the downstream increases more than 35% when the free stream Mach number is increased from 2 to 4.

  • effect of fuel jet arrangement on the Mixing Rate inside trapezoidal cavity flame holder at supersonic flow
    International Journal of Hydrogen Energy, 2019
    Co-Authors: Abdullah A A A Alrashed, R Moradi, Barzegar M Gerdroodbary, Amin Shahsavar, Pouyan Talebizadehsardari
    Abstract:

    Abstract Fuel Mixing inside the supersonic combustion chamber is a significant process for development of modern scramjets. In this article, computational fluid dynamic (CFD) approach is applied to investigate the effect of various fuel injections on the Mixing Rate inside the supersonic combustion chamber. The Mixing of hydrogen jets with four different arrangements inside the cavity flame holder is comprehensively studied. In order to examine the effect of multi jets within a cavity flameholder, a three-dimensional model is established and Navier-stocks equations are solved to simulate the flow and Mixing zone inside a cavity region. Obtained results show that the injection of hydrogen jet from the bottom of cavity flame holder considerable enhances the ignition zone within the cavity. Moreover, the backward fuel injection is more superior to forward fuel injection since low-pressure vortex could significantly distribute the fuel and enlarge the Mixing zone inside the cavity flame holder.

Barzegar M Gerdroodbary - One of the best experts on this subject based on the ideXlab platform.

  • computational investigation of multi cavity fuel injection on hydrogen Mixing at supersonic combustion chamber
    International Journal of Hydrogen Energy, 2020
    Co-Authors: Tran Dinh Manh, Nguyen Dang Nam, R Moradi, Barzegar M Gerdroodbary, Houman Babazadeh
    Abstract:

    Abstract Enhancement of the Mixing inside the combustor is a significant process for increasing the efficiency of the scramjet. This work applied the computational method for the investigation of the depth of the cavity on the flow feature of the multi hydrogen jet in the supersonic crossflow. The main focus of this research is to evaluate the depth of the cavity on the Mixing Rate of the hydrogen jets inside the combustion chamber. CFD method with the SST turbulence technique is applied for the simulation of the fluid flow inside the domain. The impact of the depth of the cavity, the pressure of the fuel jet and the number of the jet are comprehensively explained in this study. Our findings show that the rising of the cavity enhances the Mixing inside the domain due to more fuel distribution along the spanwise direction. Our results clearly demonstRate that replacing the single jet with 8 equivalent multi jets increases the Mixing Rate of more than 45% in the vicinity of the jet injection. Attained results revealed that increasing the jet space develops the Mixing in far downstream. Obtained results also show that Mixing intensifies 15% when jet space of 8 microjets is increased from 4 dj to 10 dj.

  • the influence of the sinusoidal shock generator on the Mixing Rate of multi hydrogen jets at supersonic flow
    Aerospace Science and Technology, 2020
    Co-Authors: Barzegar M Gerdroodbary, R Moradi, Houman Babazadeh
    Abstract:

    Abstract The Rate of fuel Mixing inside the combustor is highly significant and effective on the performance of the scramjet engine. In this study, numerical simulations are applied to study the influence of the sinusoidal shock generator on the flow structure of the multi hydrogen jet at supersonic crossflow. The primary focus of this research is to perform flow analysis to determine the role of the shock interaction produced by the presence of the shock generator on the Rate of Mixing in the downstream of the fuel jets. To simulate the flow, the CFD method with the K-w turbulence model is applied to capture the shock formation inside the domain. According to our results, the Mixing Rate increases by approximately 40% as the amplitude of the sinusoidal shock generator increases from 2 to 5 mm. Besides, it is found that the fuel distribution becomes uniform when the produced shock generator is more strengthen.

  • the influence of upstream wavy surface on the Mixing zone of the transverse hydrogen jet at supersonic free stream
    Aerospace Science and Technology, 2019
    Co-Authors: Barzegar M Gerdroodbary, R Moradi, Iskander Tlili
    Abstract:

    Abstract In this study, the computational fluid dynamic is applied to investigate the impact of the upstream wavy surface on the Mixing Rate of the hydrogen fuel jet. The flow feature analyses are also performed to disclose the man influence of the upstream wavy surface on the Mixing zone and fuel penetration in the downstream of the jet. To simulate the jet interaction with supersonic free stream, Navier-Stokes equations are coupled with conservation equations of energy and species equation. Since the interaction of the transverse fuel jet with a supersonic mainstream is a complex, a three-dimensional model with high resolution is produced for our investigations. The impact of the supersonic Mach number on the efficiency of the fuel Mixing in the presence of the sinusoidal wavy surface. Comprehensive parametric studies are done to reveal the influence of the jet pressure and wavy profile on the Mixing performance in the downstream of the jet. According to obtained results, the Mixing Rate of the fuel in the downstream increases more than 35% when the free stream Mach number is increased from 2 to 4.

  • effect of fuel jet arrangement on the Mixing Rate inside trapezoidal cavity flame holder at supersonic flow
    International Journal of Hydrogen Energy, 2019
    Co-Authors: Abdullah A A A Alrashed, R Moradi, Barzegar M Gerdroodbary, Amin Shahsavar, Pouyan Talebizadehsardari
    Abstract:

    Abstract Fuel Mixing inside the supersonic combustion chamber is a significant process for development of modern scramjets. In this article, computational fluid dynamic (CFD) approach is applied to investigate the effect of various fuel injections on the Mixing Rate inside the supersonic combustion chamber. The Mixing of hydrogen jets with four different arrangements inside the cavity flame holder is comprehensively studied. In order to examine the effect of multi jets within a cavity flameholder, a three-dimensional model is established and Navier-stocks equations are solved to simulate the flow and Mixing zone inside a cavity region. Obtained results show that the injection of hydrogen jet from the bottom of cavity flame holder considerable enhances the ignition zone within the cavity. Moreover, the backward fuel injection is more superior to forward fuel injection since low-pressure vortex could significantly distribute the fuel and enlarge the Mixing zone inside the cavity flame holder.

  • injection of multi hydrogen jets within cavity flameholder at supersonic flow
    International Journal of Hydrogen Energy, 2019
    Co-Authors: Amirhossein Edalatpour, R Moradi, Barzegar M Gerdroodbary, A Hassanvand, Younes Amini
    Abstract:

    Abstract Efficient distribution of hydrogen gas inside the supersonic chamber is the main challenge for the increasing the performance of the supersonic vehicles. In this study, the new injection arrangements of the multi hydrogen jets within the cavity flameholder are comprehensively studied at a supersonic free stream. In order to investigate the effect of multi jets within a cavity flameholder, a three-dimensional model is developed and computational technique is used to simulate the flow and Mixing zone inside this region. The influence of important parameters such as the pressure of jet and free stream Mach number is investigated to illustRate the flow pattern and evaluate the Mixing Rate in the supersonic combustion chamber. Obtained results show that the rise of the total pressure of hydrogen jet enlarges the ignition zone within the cavity. Furthermore, the increase of free stream Mach number limited the Mixing Rate and jet interaction. Our findings confirm that fuel jet with PR = 0.5 significantly enhances the performance of the cavity flameholder inside the scramjet.

Michio Sadatomi - One of the best experts on this subject based on the ideXlab platform.

  • single and two phase turbulent Mixing Rate between subchannels in triangle tight lattice rod bundle
    Jsme International Journal Series B-fluids and Thermal Engineering, 2006
    Co-Authors: Akimaro Kawahara, Michio Sadatomi, Hiroyuki Kudo, Keiko Kano
    Abstract:

    In order to obtain the data on turbulent Mixing Rate between triangle tight lattice subchannels, which will be adopted as the next generation BWR fuel rod bundle, adiabatic experiments were conducted for single- and two-phase flows under hydrodynamic equilibrium flow conditions. The gas and liquid Mixing Rates measured for two-phase flows were found to be affected by the void fraction and/or flow regime, as reported in our previous study on a simulated square lattice rod bundle channel having hydraulic diameters of about four times larger than the present tight lattice channel. Comparing the present Mixing Rate data with those for the square lattice channel and a triangle one in other institution, we found that the Mixing Rate was considerably smaller in the present channel than the other ones, i.e., a channel size effect.

  • single and two phase turbulent Mixing Rate between adjacent subchannels in a vertical 2 3 rod array channel
    International Journal of Multiphase Flow, 2004
    Co-Authors: Michio Sadatomi, Akimaro Kawahara, Keiko Kano, Y Sumi
    Abstract:

    Abstract To complete a subchannel analysis code for prediction of thermal–hydraulic behavior of a coolant in BWR fuel rod bundle, an accuRate estimation of fluid transfer between subchannels is essential. Under two-phase gas–liquid flow conditions, the fluid transfer is usually subdivided into turbulent Mixing, void drift and diversion cross-flow. We focused on the turbulent Mixing in this study. Until now, experimental data on two-phase turbulent Mixing Rate have been obtained exclusively for simpler channels with two subchannels alone, and prediction methods of the Mixing Rates have been proposed based on such data. In order to obtain data necessary to validate the prediction methods, we newly constructed a vertical test channel simulating a BWR fuel rod bundle, which contained six rods in a rectangular array and two kinds of six subchannels. Using this channel, flow distributions and turbulent Mixing Rates of both gas and liquid phases were measured for single-phase water and two-phase air–water flows under a hydrodynamic equilibrium flow condition at ambient pressure. In this paper, the experimental data on turbulent Mixing Rates in comparison with the data for two-subchannel system at 0.34 MPa obtained by others are presented and discussed.

  • prediction of turbulent Mixing Rates of both gas and liquid phases between adjacent subchannels in a two phase slug churn flow
    Nuclear Engineering and Design, 2000
    Co-Authors: Akimaro Kawahara, Michio Sadatomi, Takayoshi Tomino, Yoshifusa Sato
    Abstract:

    Abstract This paper presents a slug-churn flow model for predicting turbulent Mixing Rates of both gas and liquid phases between adjacent subchannels in a BWR fuel rod bundle. In the model, the Mixing Rate of the liquid phase is calculated as the sum of the three components, i.e. turbulent diffusion, convective transfer and pressure difference fluctuations between the subchannels. The components of turbulent diffusion and convective transfer are calculated from Sadatomi et al.'s [Nucl. Eng. Des. 162 (1996) 245–256] method, applicable to single-phase turbulent Mixing, by considering the effect of the increment of liquid velocity due to the presence of gas phase. The component of the pressure difference fluctuations is evaluated from a newly developed correlation. The Mixing Rate of the gas phase, on the other side, is calculated from a simple relation of Mixing Rate between gas and liquid phases. The validity of the proposed model has been confirmed with the turbulent Mixing Rates data of Rudzinski et al. [Can. J. Chem. Eng. 50 (1972) 297–299] as well as the present authors.

  • prediction of gas and liquid turbulent Mixing Rates between rod bundle subchannels in a two phase slug churn flow
    Transactions of the Japan Society of Mechanical Engineers. B, 2000
    Co-Authors: Akimaro Kawahara, Michio Sadatomi, Takayoshi Tomino
    Abstract:

    This paper presents a slug-churn flow model for predicting turbulent Mixing Rates of both gas and liquid phases between adjacent subchannels in a BWR fuel rod bundle. In the model, the Mixing Rate of the liquid phase is calculated as the sum of the three components, i.e., turbulent diffusion, convective transfer and pressure difference fluctuations between the subchannels. The components of turbulent diffusion and convective transfer are calculated from Sadatomi et al.'s (1996) method, applicable to single-phase turbulent Mixing, by considering the effect of the increment of liquid velocity due to the presence of gas phase. The component of the pressure difference fluctuations is evaluated from a newly developed correlation. The Mixing Rate of the gas phase, on the other side, is calculated from a simple relation of Mixing Rate between gas and liquid phases. The validity of the proposed model has been confirmed with the turbulent Mixing Rates data of Rudzinski et al. as well as the present authors.

  • The turbulent Mixing Rate and the fluctuations of static pressure difference between adjacent subchannels in a two-phase subchannel flow
    Nuclear Engineering and Design, 1997
    Co-Authors: Akimaro Kawahara, Yoshifusa Sato, Michio Sadatomi
    Abstract:

    Turbulent Mixing Rate between adjacent subchannels in a two-phase flow has been known to be strongly dependent on the flow pattern. In this study, flow visualization was made to investigate the mechanism of the turbulent Mixing between subchannels in a two-phase flow under hydrodynamic equilibrium conditions. The test channel was a vertical multiple channel consisting of two identical rectangular subchannels, and the working fluids were air and water. It was observed in slug-churn flows that a large scale inter-subchannel liquid flow occurs in front of the nose of a large gas bubble and behind the tail when the bubble axially passes through the subchannel, and thus a high turbulent Mixing Rate of the liquid phase results. In order to know driving force of such a large scale inter-subchannel flow, measurement of instantaneous static pressure difference between the subchannels was also made. The result showed that there is a close relationship between the liquid phase turbulent Mixing Rate and the magnitude of the pressure difference fluctuations.

Houman Babazadeh - One of the best experts on this subject based on the ideXlab platform.

  • computational investigation of multi cavity fuel injection on hydrogen Mixing at supersonic combustion chamber
    International Journal of Hydrogen Energy, 2020
    Co-Authors: Tran Dinh Manh, Nguyen Dang Nam, R Moradi, Barzegar M Gerdroodbary, Houman Babazadeh
    Abstract:

    Abstract Enhancement of the Mixing inside the combustor is a significant process for increasing the efficiency of the scramjet. This work applied the computational method for the investigation of the depth of the cavity on the flow feature of the multi hydrogen jet in the supersonic crossflow. The main focus of this research is to evaluate the depth of the cavity on the Mixing Rate of the hydrogen jets inside the combustion chamber. CFD method with the SST turbulence technique is applied for the simulation of the fluid flow inside the domain. The impact of the depth of the cavity, the pressure of the fuel jet and the number of the jet are comprehensively explained in this study. Our findings show that the rising of the cavity enhances the Mixing inside the domain due to more fuel distribution along the spanwise direction. Our results clearly demonstRate that replacing the single jet with 8 equivalent multi jets increases the Mixing Rate of more than 45% in the vicinity of the jet injection. Attained results revealed that increasing the jet space develops the Mixing in far downstream. Obtained results also show that Mixing intensifies 15% when jet space of 8 microjets is increased from 4 dj to 10 dj.

  • the effect of sinusoidal wall on hydrogen jet Mixing Rate considering supersonic flow
    Energy, 2020
    Co-Authors: Tran Dinh Manh, Mostafa Barzegar Gerdroodbary, Nguyen Dang Nam, R Moradi, Houman Babazadeh
    Abstract:

    Abstract The efficiency of the scramjet is highly associated with the Rate of the Mixing through the combustion tank. In current article, simulation approach was used to inspect the effect of the sinusoidal wall on hydrogen Mixing cross-flow jet. The key focus of current paper is to exhibit the role of various sinusoidal profiles on the flow structure and streamline pattern of the mainstream and fuel jet. To simulate the flow feature, a 3D model was chosen and Navier-stocks equations were solved with energy and species mass transport equations to evaluate the Mixing Rate of hydrogen jet. Hydrogen gas is injected through the nozzle in the downstream of the sinusoidal wave. The impact of total jet pressure on the flow feature is exclusively studied. Also, the Mixing zones of the various models are compared. Attained results display that the appearance of the wavy wall augments the Mixing Rate when the frequency of the sinusoidal wave is high enough. Our findings also reveal that using extended surface has less effect in high pressure condition. The comparison of the Mixing Rate shows that the presence of sinusoidal wavy wall with frequency of 1200 increases the Mixing Rate more than 25% than simple flat surface.

  • the influence of the sinusoidal shock generator on the Mixing Rate of multi hydrogen jets at supersonic flow
    Aerospace Science and Technology, 2020
    Co-Authors: Barzegar M Gerdroodbary, R Moradi, Houman Babazadeh
    Abstract:

    Abstract The Rate of fuel Mixing inside the combustor is highly significant and effective on the performance of the scramjet engine. In this study, numerical simulations are applied to study the influence of the sinusoidal shock generator on the flow structure of the multi hydrogen jet at supersonic crossflow. The primary focus of this research is to perform flow analysis to determine the role of the shock interaction produced by the presence of the shock generator on the Rate of Mixing in the downstream of the fuel jets. To simulate the flow, the CFD method with the K-w turbulence model is applied to capture the shock formation inside the domain. According to our results, the Mixing Rate increases by approximately 40% as the amplitude of the sinusoidal shock generator increases from 2 to 5 mm. Besides, it is found that the fuel distribution becomes uniform when the produced shock generator is more strengthen.

Akimaro Kawahara - One of the best experts on this subject based on the ideXlab platform.

  • single and two phase turbulent Mixing Rate between subchannels in triangle tight lattice rod bundle
    Jsme International Journal Series B-fluids and Thermal Engineering, 2006
    Co-Authors: Akimaro Kawahara, Michio Sadatomi, Hiroyuki Kudo, Keiko Kano
    Abstract:

    In order to obtain the data on turbulent Mixing Rate between triangle tight lattice subchannels, which will be adopted as the next generation BWR fuel rod bundle, adiabatic experiments were conducted for single- and two-phase flows under hydrodynamic equilibrium flow conditions. The gas and liquid Mixing Rates measured for two-phase flows were found to be affected by the void fraction and/or flow regime, as reported in our previous study on a simulated square lattice rod bundle channel having hydraulic diameters of about four times larger than the present tight lattice channel. Comparing the present Mixing Rate data with those for the square lattice channel and a triangle one in other institution, we found that the Mixing Rate was considerably smaller in the present channel than the other ones, i.e., a channel size effect.

  • single and two phase turbulent Mixing Rate between adjacent subchannels in a vertical 2 3 rod array channel
    International Journal of Multiphase Flow, 2004
    Co-Authors: Michio Sadatomi, Akimaro Kawahara, Keiko Kano, Y Sumi
    Abstract:

    Abstract To complete a subchannel analysis code for prediction of thermal–hydraulic behavior of a coolant in BWR fuel rod bundle, an accuRate estimation of fluid transfer between subchannels is essential. Under two-phase gas–liquid flow conditions, the fluid transfer is usually subdivided into turbulent Mixing, void drift and diversion cross-flow. We focused on the turbulent Mixing in this study. Until now, experimental data on two-phase turbulent Mixing Rate have been obtained exclusively for simpler channels with two subchannels alone, and prediction methods of the Mixing Rates have been proposed based on such data. In order to obtain data necessary to validate the prediction methods, we newly constructed a vertical test channel simulating a BWR fuel rod bundle, which contained six rods in a rectangular array and two kinds of six subchannels. Using this channel, flow distributions and turbulent Mixing Rates of both gas and liquid phases were measured for single-phase water and two-phase air–water flows under a hydrodynamic equilibrium flow condition at ambient pressure. In this paper, the experimental data on turbulent Mixing Rates in comparison with the data for two-subchannel system at 0.34 MPa obtained by others are presented and discussed.

  • prediction of turbulent Mixing Rates of both gas and liquid phases between adjacent subchannels in a two phase slug churn flow
    Nuclear Engineering and Design, 2000
    Co-Authors: Akimaro Kawahara, Michio Sadatomi, Takayoshi Tomino, Yoshifusa Sato
    Abstract:

    Abstract This paper presents a slug-churn flow model for predicting turbulent Mixing Rates of both gas and liquid phases between adjacent subchannels in a BWR fuel rod bundle. In the model, the Mixing Rate of the liquid phase is calculated as the sum of the three components, i.e. turbulent diffusion, convective transfer and pressure difference fluctuations between the subchannels. The components of turbulent diffusion and convective transfer are calculated from Sadatomi et al.'s [Nucl. Eng. Des. 162 (1996) 245–256] method, applicable to single-phase turbulent Mixing, by considering the effect of the increment of liquid velocity due to the presence of gas phase. The component of the pressure difference fluctuations is evaluated from a newly developed correlation. The Mixing Rate of the gas phase, on the other side, is calculated from a simple relation of Mixing Rate between gas and liquid phases. The validity of the proposed model has been confirmed with the turbulent Mixing Rates data of Rudzinski et al. [Can. J. Chem. Eng. 50 (1972) 297–299] as well as the present authors.

  • prediction of gas and liquid turbulent Mixing Rates between rod bundle subchannels in a two phase slug churn flow
    Transactions of the Japan Society of Mechanical Engineers. B, 2000
    Co-Authors: Akimaro Kawahara, Michio Sadatomi, Takayoshi Tomino
    Abstract:

    This paper presents a slug-churn flow model for predicting turbulent Mixing Rates of both gas and liquid phases between adjacent subchannels in a BWR fuel rod bundle. In the model, the Mixing Rate of the liquid phase is calculated as the sum of the three components, i.e., turbulent diffusion, convective transfer and pressure difference fluctuations between the subchannels. The components of turbulent diffusion and convective transfer are calculated from Sadatomi et al.'s (1996) method, applicable to single-phase turbulent Mixing, by considering the effect of the increment of liquid velocity due to the presence of gas phase. The component of the pressure difference fluctuations is evaluated from a newly developed correlation. The Mixing Rate of the gas phase, on the other side, is calculated from a simple relation of Mixing Rate between gas and liquid phases. The validity of the proposed model has been confirmed with the turbulent Mixing Rates data of Rudzinski et al. as well as the present authors.

  • The turbulent Mixing Rate and the fluctuations of static pressure difference between adjacent subchannels in a two-phase subchannel flow
    Nuclear Engineering and Design, 1997
    Co-Authors: Akimaro Kawahara, Yoshifusa Sato, Michio Sadatomi
    Abstract:

    Turbulent Mixing Rate between adjacent subchannels in a two-phase flow has been known to be strongly dependent on the flow pattern. In this study, flow visualization was made to investigate the mechanism of the turbulent Mixing between subchannels in a two-phase flow under hydrodynamic equilibrium conditions. The test channel was a vertical multiple channel consisting of two identical rectangular subchannels, and the working fluids were air and water. It was observed in slug-churn flows that a large scale inter-subchannel liquid flow occurs in front of the nose of a large gas bubble and behind the tail when the bubble axially passes through the subchannel, and thus a high turbulent Mixing Rate of the liquid phase results. In order to know driving force of such a large scale inter-subchannel flow, measurement of instantaneous static pressure difference between the subchannels was also made. The result showed that there is a close relationship between the liquid phase turbulent Mixing Rate and the magnitude of the pressure difference fluctuations.