• 제목/요약/키워드: Thermal radiation and chemical reaction

검색결과 32건 처리시간 0.031초

평형화학반응과 복사열전달을 고려한 로켓 플룸 유동 해석 (Numerical Study of Rocket Exhaust Plume with Equilibrium Chemical Reaction and Thermal Radiation)

  • 신재렬;최정열;최환석
    • 한국전산유체공학회:학술대회논문집
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    • 한국전산유체공학회 2004년도 춘계 학술대회논문집
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    • pp.146-153
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    • 2004
  • The Numerical study has been carried out to investigate the effects of chemical reaction and thermal radiation on the rocket plume flow-field at various altitudes. The theoretical formulation is based on the Navier-Stokes equations for compressible flows along with the infinitely fast chemistry and thermal radiation. The governing equations were solved by a finite volume fully-implicit TVD(Total Variation Diminishing) code which uses Roe's approximate Riemann solver and MUSCL(Monotone Upstream-centered Schemes for Conservation Laws) scheme. LU-SGS (Lower Upper Symmetric Gauss Seidel) method is used for the implicit solution strategy. An equilibrium chemistry module for hydrocarbon mixture with detailed thermo-chemical properties and a thermal radiation module for optically thin media were incorporated with the fluid dynamics code. In this study, kerosene-fueled rocket was assumed operating at O/F ratio of 2.34 with a nozzle expansion ratio of 6.14. Flight conditions considered were Mach number zero at ground level, Mach number 1.16 at altitude 5.06km and Mach number 2.9 at altitude 17.34km. Numerical results gave the understandings on the detailed plume structures at different altitude conditions. The diffusive effect of the thermal radiation on temperature field and the effect of chemical recombination during the expansion process could be also understood. By comparing the results from frozen flow and infinitely fast chemistry assumptions, the excess temperature of the exhaust gas resulting from the chemical recombination seems to be significant and cannot be neglected in the view point of performance, thermal protection and flow physics.

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Effect of a chemical reaction on magnetohydrodynamic (MHD) stagnation point flow of Walters-B nanofluid with newtonian heat and mass conditions

  • Qayyum, Sajid;Hayat, Tasawar;Shehzad, Sabir A.;Alsaedi, Ahmed
    • Nuclear Engineering and Technology
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    • 제49권8호
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    • pp.1636-1644
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    • 2017
  • The main purpose of this article is to describe the magnetohydrodynamic stagnation point flow of Walter-B nanofluid over a stretching sheet. The phenomena of heat and mass transfer are based on the involvement of thermal radiation and chemical reaction. Characteristics of Newtonian heating are given special attention. The Brownian motion and thermophoresis models are introduced in the temperature and concentration expressions. Appropriate variables are implemented for the transformation of partial differential frameworks into sets of ordinary differential equations. Plots for velocity, temperature, and nanoparticle concentration are displayed and analyzed for governing parameters. The skin friction coefficient and local Nusselt and Sherwood numbers are studied using numerical values. The temperature and heat transfer rate are enhanced within the frame of the thermal conjugate parameter.

$CO_2$ 첨가가 $CH_4$-공기 대향류 확산화염의 구조 및 NOx 생성에 미치는 영향 (Effect of $CO_2$ Addition on Flame Structure and NOx Formation of $CH_4-Air$ Counterflow Diffusion Flames)

  • 이승로;한지웅;이창언
    • 한국연소학회지
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    • 제4권2호
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    • pp.97-108
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    • 1999
  • This numerical study was to investigate the effect of $CO_2$ addition on the structures and NOx formation characteristics in $CH_4$ counterflow diffusion flame. The importance of radiation effect was identified and $CO_2$ addition effect was investigated in terms of thermal and chemical reaction effect. Also the causes of NOx reduction were clarified by separation method of each formation mechanisms. The results were as follows : The radiation effect was intensified by $CO_2$ addition. Thermal effect mainly contributed to the changes in flame structure and the amount of NO formation but the chemical reaction effect also cannot be neglected. The reduction of thermal NO was dominant with respect to reduction rate, but that of prompt NO was dominant with respect to total amount.

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A Thermo chemical Study of Arcjet Thruster Flow Field

  • J-R. Shin;S. Oh;Park, J-Y
    • 한국추진공학회:학술대회논문집
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    • 한국추진공학회 2004년도 제22회 춘계학술대회논문집
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    • pp.257-261
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    • 2004
  • Computational fluid dynamics analysis was carried out for thermo-chemical flow field in Arcjet thruster with mono-propellant Hydrazine ($N_2$H$_4$) as a working fluid. The theoretical formulation is based on the Reynolds Averaged Navier-Stokes equations for compressible flows with thermal radiation. The electric potential field governed by Maxwell equation is loosely coupled with the fluid dynamics equations through the Ohm heating and Lorentz force. Chemical reactions were assumed being infinitely fast due to the high temperature field inside the arcjet thruster. An equilibrium chemistry module for nitrogen-hydrogen mixture and a thermal radiation module for optically thin media were incorporated with the fluid dynamics code. Thermo-physical process inside the arcjet thruster was understood from the flow field results and the performance prediction shows that the thrust force is increased by amount of 3 times with 0.6KW arc heating.

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$CH_4/Air-CO_2$ 대향류 확산화염의 NOx 생성 특성 및 화염구조 (NOx Formation and Flame Structure in $CH_4/Air-CO_2$ Counterflow Diffusion Flames)

  • 한지웅;이승로;이창언
    • 대한기계학회:학술대회논문집
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    • 대한기계학회 2000년도 춘계학술대회논문집B
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    • pp.949-955
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    • 2000
  • Numerical study with detailed chemistry has been conducted to investigate the NOx formation and structure in $CH_4/Air-CO_2$ counterflow diffusion flames. The importance of radiation effect is identified and the role of $CO_2$ addition is addressed to thermal and chemical reaction effects, which can be precisely specified through the introduction of an imaginary species. Also NO separation technique is utilized to distinguish the contribution of thermal and prompt NO formation mechanisms. The results are as follows : The radiation effect is dominant at low strain rates and it is intensified by $CO_2$ addition. Thermal effect mainly contributes to the changes in flame structure and the amount of NO formation but the chemical reaction effect also cannot be neglected. It is noted that flame structure is changed considerably due to the addition of $CO_2$ in such a manner that the path of methane oxidation prefers to take $CH_4 {\rightarrow}CH_3{\rightarrow}C_2H_6{\rightarrow}C_2H_5$ instead of $CH_4 {\rightarrow}CH_3{\rightarrow}CH_2{\rightarrow}CH$. At low strain rate(a=10) the reduction of thermal NO is dominant with respect to reduction rate, but that of prompt NO is dominant with respect to total amount.

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열복사에 의한 수직연료면의 점화현상 해석 (Ignition of a Vertically Positioned Fuel Plate by Thermal Radiation)

  • 한조영;백승욱
    • 대한기계학회논문집
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    • 제19권9호
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    • pp.2353-2364
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    • 1995
  • The ignition phenomena of a solid fuel plate of polymethyl-methacrylate(PMMA), which is vertically positioned and exposed to a thermal radiation source, is numerically studied here. A two-dimensional transient model includes such various aspects as thermal decomposition of PMMA, gas phase radiation absorption, gas phase chemical reaction and air entrainment by natural convection. Whereas the previous studies considers the problem approximately in a one-dimensional form by neglecting the natural convection, the present model takes account of the two-dimensional effect of radiation and air entrainment. The inert heating of the solid fuel is also taken into consideration. Radiative heat transfer is incorporated by th Discrete Ordinates Method(DOM) with the absorption coefficient evaluated using gas species concentration. The thermal history of the solid fuel plate shows a good agreement compared with experimental results. Despite of induced natural convective flow that induces heat loss from the fuel surface, the locally absorbed radiant energy, which is converted to the internal energy, is found to play an important role in the onset of gas phase ignition. The ignition is considered to occur when the rate of variation of gas phase reaction rate reaches its maximum value. Once the ignition takes place, the flame propagates downward.

SORET, HALL CURRENT, ROTATION, CHEMICAL REACTION AND THERMAL RADIATION EFFECTS ON UNSTEADY MHD HEAT AND MASS TRANSFER NATURAL CONVECTION FLOW PAST AN ACCELERATED VERTICAL PLATE

  • VENKATESWARLU, M.;LAKSHMI, D. VENKATA;RAO, K. NAGA MALLESWARA
    • Journal of the Korean Society for Industrial and Applied Mathematics
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    • 제20권3호
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    • pp.203-224
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    • 2016
  • The heat and mass transfer characteristics of the unsteady hydromagnetic natural convection flow with Hall current and Soret effect of an incompressible, viscous, electrically conducting, heat absorbing and optically thin radiating fluid flow past a suddenly started vertical infinite plate through fluid saturated porous medium in a rotating environment are taken into account in this paper. Derivations of exact analytical solutions are aimed under different physical properties. The velocity, concentration and temperature profiles, Sherwood number and Nusselt number are easily examined and discussed via the closed forms obtained. Soret effect and permeability parameter tends to accelerate primary and secondary fluid velocities whereas hall current, radiation and heat absorption have reverse effect on it. Radiation and heat absorption have tendency to enhance rate of heat transfer at the plate. The results obtained here may be further used to verify the validity of obtained numerical solutions for more complicated transient free convection fluid flow problems.

수소-산소 대향류 확산 화염에서 산화제와 연료측에 첨가된 Co2의 화학적 효과에 관한 수치해석 연구 (A Numerical Study on Chemical Effects of Co2 Addition to Oxidizer and Fuel Streams in H2-O2 Counterflow Diffusion Flames)

  • 이기만;박정
    • 대한기계학회논문집B
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    • 제28권4호
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    • pp.371-381
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    • 2004
  • Numerical simulation of $CO_2$ addition effects to fuel and oxidizer streams on flame structure has been conducted with detailed chemistry in H$_2$-O$_2$ diffusion flames of a counterflow configuration. An artificial species, which displaces added $CO_2$ in the fuel- and oxidizer-sides and has the same thermochemical, transport, and radiation properties to that of added $CO_2$, is introduced to extract pure chemical effects in flame structure. Chemical effects due to thermal dissociation of added $CO_2$ causes the reduction flame temperature in addition to some thermal effects. The reason why flame temperature due to chemical effects is larger in cases of $CO_2$ addition to oxidizer stream is well explained though a defined characteristic strain rate. The produced CO is responsible for the reaction, $CO_2$+H=CO+OH and takes its origin from chemical effects due to thermal dissociation. It is also found that the behavior of produced CO mole fraction is closely related to added $CO_2$ mole fraction, maximum H mole fraction and its position, and maximum flame temperature and its position.

수치해석을 통한 Spiral 형상 화학 반응기의 열전달 특성 (Heat Transfer Characteristic of the Spiral Type Solar Chemical Reactor)

  • 정영국;이진규;이주한;서태범
    • 설비공학논문집
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    • 제22권1호
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    • pp.40-48
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    • 2010
  • The purpose of the research is to develop the high performance solar chemical reactor for producing hydrogen using steam reforming reaction of methane. A specific shape chemical reactor is suggested : spiral type reactor. The reactor is installed on the dish-type solar thermal system of Inha University. The temperatures, $CH_4$ conversion rates, and Hz proportion are measured. At specific condition, $CH_4$ conversion rates of the spiral type reactor are about 91%, and Hz proportion are about 66%. The spiral type reactor gives reasonably good performance without any problems caused by highly concentrated solar radiation.

Numerical Study of Entropy Generation with Nonlinear Thermal Radiation on Magnetohydrodynamics non-Newtonian Nanofluid Through a Porous Shrinking Sheet

  • Bhatti, M.M.;Abbas, T.;Rashidi, M.M.
    • Journal of Magnetics
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    • 제21권3호
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    • pp.468-475
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    • 2016
  • In this article, entropy generation on MHD Williamson nanofluid over a porous shrinking sheet has been analyzed. Nonlinear thermal radiation and chemical reaction effects are also taken into account with the help of energy and concentration equation. The fluid is electrically conducting by an external applied magnetic field while the induced magnetic field is assumed to be negligible due to small magnetic Reynolds number. The governing equations are first converted into the dimensionless expression with the help of similarity transformation variables. The solution of the highly nonlinear coupled ordinary differential equation has been obtained with the combination of Successive linearization method (SLM) and Chebyshev spectral collocation method. Influence of all the emerging parameters on entropy profile, temperature profile and concentration profile are plotted and discussed. Nusselt number and Sherwood number are also computed and analyzed. It is observed that entropy profile increases for all the physical parameters. Moreover, it is found that when the fluid depicts non-Newtonian (Williamson fluid) behavior then it causes reduction in the velocity of fluid, however, non-Newtonian behavior enhances the temperature and nanoparticle concentration profile.