Numerical analysis of the convective heat transfer in a combustor cooling jacket
- Authors: Gutierrez, Gustavo , Jen, Tien-Chien , Yan, Tuan-Zhou
- Date: 2003
- Subjects: Combustor cooling , Convective heat transfer , Numerical analysis
- Language: English
- Type: Conference proceedings
- Identifier: http://hdl.handle.net/10210/16022 , uj:15729 , Citation: • Gutierrez, G., Jen, T.C., and Yan, T., 2003, “Numerical Analysis of the Convective Heat Transfer in a Combustor Cooling Jacket,” International Mechanical Engineering and Congress Exposition, November 16-21, 2003, Washington, D.C., Vol. 3, pp. 29-37. IMECE2003-42912. ISSN: 0-7918-3718-1.
- Description: Abstract: In any combustors and chemical reactors, to achieve high efficiency it is very important to maintain the high gas temperature inside the combustion chamber without significant deterioration of the materials of the walls. Thus, a critical aspect of the design of a combustor or reactor is the development of a method to cool the inner walls of a combustor such that the temperatures on the inner wall are well below the temperature a material can sustain. A typical method to cool a combustor chamber is to use a cooling jacket adjacent to the inner wall of the combustor. In general, the efficiency of this cooling jacket depends on the heat removal capability of the cooling water and the flow channel geometry. It is critically important to control these parameters to enhance the performance of the combustion chamber by decreasing the inner wall temperature below its material limit Sφ : source term in the generic property φ Vr ,Vθ , Vz : reduced velocities in the r, θ , and z direction respectively [m/s] T : temperature [ºC] Tinn : inner temperature [ºC] T∞ : ambient temperature [ºC] U0 : inlet velocity [m/s] Greek ρ : density [kg/m3] φ : generic property μ : dynamic viscosity [kg/m-s] Γ : diffusivity for the generic property φ Ω : angular velocity [rad/s] This study considers a cylindrical combustor, rotating around its axis. A detailed investigation of the fluid flow and heat transfer processes throughout the cooling jacket is performed. A two-dimensional axial symmetric Navier-Stokes equations and energy equation as a conjugate problem are solved. The flow patterns and temperature distributions of the cooling jacket under the effect of rotation are presented. Also, local friction factor and Nusselt number are calculated along the axial direction.
- Full Text:
Transient heat transfer analysis on a heat pipe with experimental validation
- Authors: Gutierrez, Gustavo , Catano, Juan , Jen, Tien-Chien , Liao, Quan
- Date: 2006
- Subjects: Numerical analysis , Heat transfer , Heat pipes
- Type: Article
- Identifier: uj:5270 , http://hdl.handle.net/10210/14939
- Description: In this study, a transient analysis of the performance of a heat pipe with a wick structure is performed. A complete formulation of the equation governing the operation of a heat pipe during transient conditions are presented and discussed. For the vapor flow, the conventional Navier-Stokes equations are used. For the liquid flow in the wick structure, which is modeled as a porous media, volume averaged Navier-Stokes equations are adopted. The energy equation is solved for the solid wall and wick structure of the heat pipe. The energy and momentum equations are coupled through the heat flux at the liquid-vapor interface that defines the suction and blowing velocities for the liquid and vapor flow. The evolution of the vaporliquid interface temperature is coupled through the heat flux at this interface that defines the mass flux to the vapor and the new saturation conditions to maintain a fully saturated vapor at all time. A control volume approach is used in the development of the numerical scheme. A parametric study is conducted to study the effect of different parameters that affect the thermal performance of the heat pipe. And experimental setup is developed and numerical res ults are validated with experimental data. The results of this study will be useful for the heat pipe design and implementation in processes that are essentially transient.
- Full Text:
Numerical analysis in interrupted cutting tool temperatures
- Authors: Jen, Tien-Chien , Gutierrez, Gustavo , Eapen, Sunil
- Date: 2011
- Subjects: Numerical analysis , Cutting tools , Cutting temperatures
- Type: Article
- Identifier: uj:5243 , ISSN 1040-7782 , http://hdl.handle.net/10210/14843
- Description: In any cutting process, plastic deformation involved in chip formation and friction between the tool and the workpiece produces heat by the conversion of mechanical energy. A portion of this heat conducts into the tool and results in high temperatures near the cutting edge. As the temperature increases, the tool becomes softer and wears more rapidly, thus having a negative impact on tool life. In many cutting processes, tool life, or tool wear, is the major limitation to the process viability. Increased temperature also affects the dimensional accuracy of the products and machining efficiency. Because of these considerations, it is crucial to be able to predict accurately the tool temperature. Cutting temperatures have been studied widely for a number of years. Most research, however, has been restricted to steady state temperatures in relatively simple processes, such as orthogonal cutting or cylindrical turning, in which the cutting speed, feed rate, and the depth of cut are constant [1^3, 17, 21, 24]. In most industrial machining processes, however, these parameters vary with time so that a steady state temperature assumption may not be valid.
- Full Text: