• Title/Summary/Keyword: Transonic Moist Air Flow

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THE EFFECTS OF MACH NUMBER AND THICKNESS RATIO OF AIRFOIL ON TRANSONIC FLOW OF MOIST AIR AROUND A THIN AIRFOIL WITH LATENT HEAT TRANSFER (잠열 전달이 일어나는 얇은 익형주위의 천음속 습공기 유동에서의 마하수와 익형 두께비의 영향)

  • Lee, J.C.
    • Journal of computational fluids engineering
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    • v.17 no.4
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    • pp.93-102
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    • 2012
  • Once the condensation of water vapor in moist air around a thin airfoil occurs, liquid droplets nucleate. The condensation process releases heat to the surrounding gaseous components of moist air and significantly affects their thermodynamic and flow properties. As a results, variations in the aerodynamic performance of airfoils can be found. In the present work, the effects of upstream Mach number and thickness ratio of airfoil on the transonic flow of moist air around a thin airfoil are investigated by numerical analysis. The results shows that a significant condensation occurs as the upstream Mach number is increased at the fixed thickness ratio of airfoil($\epsilon$=0.12) and as the thickness ratio of airfoil is increased at the fixed upstream Mach number($M_{\infty}$=0.80). The condensate mass fraction is also increased and dispersed widely around an airfoil as the upstream Mach number and thickness ratio of airfoil are increased. The position of shock wave for moist air flow move toward the leading edge of airfoil when it is compared with the position of shock wave for dry air.

A Study of the Passive Shock/Boundary Layer Interaction Control in Transonic Moist Air Flow (천음속 습공기 유동에서 발생하는 충격파와 경계층 간섭의 피동제어에 관한 연구)

  • Baek Seung-Cheol;Kwon Soon-Bum;Kim Heuy-Dong
    • Proceedings of the KSME Conference
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    • 2002.08a
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    • pp.161-164
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    • 2002
  • In the present study, a passive control method, using the porous wall and cavity system, is applied to the shock wave/boundary layer interactions in transonic moist air flow. The two-dimensional, unsteady, compressible Navier-Stokes equations, which are fully coupled with a droplet growth equation, are solved by the third-order MUSCL type TVD finite difference scheme. Baldwind-Lomax turbulence model is employed to close the governing equations. In order to investigate the effectiveness of the present control method, the total pressure losses of the flow and the time-dependent behaviour of shock motions are analyzed in detail. The computed results show that the present passive control method considerably reduces the total pressure losses due to the shock/boundary layer interaction in transonic moist air flow and suppresses the unsteady shock wave motions over the airfoil, as well. It is also found that the location of the porous ventilation significantly influences the control effectiveness.

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Study on the Passive Shock/Boundary Layer Interaction Control in Transonic Moist Air Flow (습공기 유동에서 발생하는 충격파와 경계층 간섭의 피동제어에 관한 연구)

  • Baek, Seung-Cheol;Kwon, Soon-Bum;Kim, Heuy-Dong
    • Journal of the Korean Society for Aeronautical & Space Sciences
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    • v.30 no.8
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    • pp.21-29
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    • 2002
  • In the present study, a passive control method, using a porous wall and cavity system, is applied to the shock wave/boundary layer interactions in transonic moist air flow. The two-dimensional, unsteady, compressible, Navier-Stokes equations, which are fully coupled with a droplet growth equation, are solved by the third-order MUSCL type TVD finite difference scheme. Baldwin-Lomax model is employed to close the governing equations. In order to investigate the effectiveness of the present control method, the total pressure loss of the flow and the time-dependent behaviour of shock motions are analyzed in detail. The computed results show that the present passive control method considerably reduces the total pressure losses due to the shock wave/boundary layer interaction in transonic moist air flow and suppresses the unsteady shock wave motions over the airfoil as well. It is also found that the location of the porous ventilation significantly affects the control effectiveness.

Passive Control of Condensation Shock Wave in a Transonic Nozzle (천음속 노즐에서 발생하는 응축충격파의 피동제어)

  • Kim, Hui-Dong;Baek, Seung-Cheol;Gwon, Sun-Beom
    • Transactions of the Korean Society of Mechanical Engineers B
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    • v.26 no.5
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    • pp.666-674
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    • 2002
  • A rapid expansion of the moist air or stream through transonic nozzle often leads to not-equilibrium condensation shock, causing a considerable amount of energy loss to the entire flow field. Depending on amount of heat released, condensation shock wave occurs in the nozzle and interacts with the boundary layer flow. In the current study, a passive control technique using a porous wall with a plenum cavity underneath is applied for purpose of alleviation the condensation shock wave in a transonic nozzle. A droplet growth equation is incorporated into two-dimensional wavier-Stokes equation systems. Computations are carried out using a third-order MUSCL type TVD finite-difference scheme with a second-order fractional time step. An experiment using an indraft transonic wind tunnel is made to validate the present computational results. The results obtained show that the magnitude of condensation shock wave is reduced by the current passive control method.

PASSlVE SHOCK CONTROL IN TRANSONIC FLOW FIELD

  • Matsuo S;Tanaka M;Setoguchi T;Kashimura H;Yasunobu T;Kim H.D
    • Journal of computational fluids engineering
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    • v.10 no.1
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    • pp.80-86
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    • 2005
  • In order to control the transonic flow field with a shock wave, a condensing flow was produced by an expansion of moist air on a circular bump model and shock waves were occurred in the supersonic parts of the fields. Furthermore, the additional passive technique of shock-boundary layer interaction using the porous wall with a cavity underneath was adopted in this flow field. The effects of these methods on the shock wave characteristics were investigated numerically. The result showed that the flow fields might be effectively controlled by the suitable combination between non-equilibrium condensation and the position of porous wall.

Passive Shock Control in Transonic Flow Field

  • Matsuo S.;Tanaka M.;Setoguchi T.;Kashimura H.;Yasunobu T.;Kim H. D.
    • 한국전산유체공학회:학술대회논문집
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    • 2003.10a
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    • pp.187-188
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    • 2003
  • In order to control the transonic flow field with shock wave, a condensing flow was produced by an expansion of moist air on a circular bump model and shock waves were occurred in the supersonic parts of the fields. Furthermore, the additional passive technique of shock - boundary layer interaction using the porous wall with a cavity underneath was adopted in this flow field. The effects of these methods on the shock wave characteristics were investigated numerically. The result showed that the flow fields might be effectively controlled by the suitable combination between non-equilibrium condensation and the position of porous wall.

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Numerical Study on the Effect of Non-Equilibrium Condensation on Drag Divergence Mach Number in a Transonic Moist Air Flow (천음속 익형 유동에서 비평형 응축이 Drag Divergence Mach Number에 미치는 영향에 관한 수치 해석적 연구)

  • Choi, Seung Min;Kang, Hui Bo;Kwon, Young Doo;Kwon, Soon Bum
    • Transactions of the Korean Society of Mechanical Engineers B
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    • v.40 no.12
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    • pp.785-792
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    • 2016
  • In the present study, the effects of non-equilibrium condensation on the drag divergence Mach number with the angle of attack in a transonic 2D moist air flow of NACA0012 are investigated using the TVD finite difference scheme. For the same ${\alpha}$, the maximum upstream Mach number of the shock wave, Mmax, and the size of supersonic bubble decrease with the increase in ${\Phi}_0$. For the same $M_{\infty}$, ${\Phi}_0$, and $T_0$, the length of the non-equilibrium condensation zone ${\Delta}_z$ decreases with increasing ${\Phi}_0$. On the other hand, because of the attenuating effect of non-equilibrium condensation on wave drag, which is related to the interaction between the shock wave and the boundary layer, the drag coefficient $C_D$ decreases with an increase in ${\Phi}_0$ for the same $M_{\infty}$ and ${\alpha}$. For the same ${\alpha}$, $M_D$ increases with increasing ${\Phi}_0$, while $M_D$ decreases with an increase in ${\alpha}$.

Effect of Nonequilibrium Condensation on the Oscillation of the Terminating Shock in a Transonic Airfoil Flow (천음속 익형 유동에 있어서 비평형 응축이 충격파 진동에 미치는 영향)

  • Kim, Jin-Soo;Lee, Sung-Jin;Alam, Miah Md. Ashraful;Kwon, Soon-Bum
    • Transactions of the Korean Society of Mechanical Engineers B
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    • v.36 no.1
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    • pp.61-66
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    • 2012
  • In this study, to find the effect of nonequilibrium condensation on the oscillation of the terminating shock wave in transonic flows, an NACA0014 airfoil flow with nonequilibrium condensation is analyzed using the total variation diminishing (TVD) numerical scheme. Transonic free stream Mach numbers of 0.81-0.87 are tested with variations in the stagnation relative humidity. For the same free stream Mach number and attack angle of ${\alpha}=0^{\circ}$, an increase in the stagnation relative humidity attenuates the strength of the terminating shock and reduces the oscillation of the terminating shock wave. Furthermore, for the same stagnation relative humidity, the larger the free stream Mach number becomes, the shorter the period of the oscillation shock wave is. The excursion distance of the oscillation shock increases with the free stream Mach numbers for the same stagnation relative humidity. Finally, it is found that for the same shock location, the strength of the oscillating shock facing upstream is stronger than that facing downstream.

Effects of Nonequilibrium Condensation on an Oblique Shock Wave in a Supersonic Nozzle of Constant Expansion Rate (팽창률이 일정한 초음속 노즐흐름에 있어서 비평형 응축이 경사충격파에 미치는 영향)

  • 강창수;권순범;김병지;홍종우
    • Transactions of the Korean Society of Mechanical Engineers
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    • v.14 no.5
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    • pp.1311-1319
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    • 1990
  • For the purpose of preventing the flow undulation in the cascade of steam turbine, the blades are made into a constant expansion rate in static pressure. And the flow in those cascades is transonic or supersonic in the range of 0.7-2.0 in Mach number. As a consequence, an oblique shock wave, known as inner or outer edge shock wave, arises in the flow of cascades. Especially when the steam in cascades is in a state of high wetness, nonequilibrium condensation and condensation shock wave occur, and they give rise to an interference with oblique shock wave. In the present study the case of expansion of moist air through a supersonic nozzle of constant expansion rate, which behaves similar to that of wet steam, was adopted. The effect of nonequilibrium condensation on the oblique shock wave generated by placing the wedge into the supersonic part of the nozzle was investigated. Furthermore, the relationship between nonequilibrium condensation zone and incident point of the oblique shock wave, oblique shock wave angle, the variations of angles of incident and reflected shock waves due to the variation of initial stagnation supersaturation and the relationship between the height of Mach stem and initial stagnation supersaturation are discussed.