Numerical Investigation of Heat Conduction With Unsteady Thermal Boundary Conditions for Internal Combustion Engine Application

Abstract

Heat transfer is one major important aspect of energy transformation in spark ignition (SI) engines. Locating hot spots in a solid wall can be used as an impetus to design a better cooling system. Fast transient heat flux between the combustion chamber and the solid wall must be investigated to understand the effects of the non-steady thermal environment. This study investigates numerical simulation of 3D transient heat diffusion phenomena in solid, exposed to steady and unsteady thermal boundary conditions. A 3D transient finite volume method to calculate heat transfer across a solid medium will be presented first. It is then validated with steady state thermal boundary conditions. The validation extends to the effects of multiple solid materials for which large thermal property difference is investigated. Finally the effects of non-steady thermal boundary environment are discussed. Numerical results are validated with available analytical solutions and are compared with FLUENT result.

Modeling IC Engine Conjugate Heat Transfer Using the KIVA Code

“…As shown in Figure 4, both numerical solutions agree with the exact solution very well. Other validations and case studies can be found in [5] and will not be repeated here. …”

“…From our numerical experience, the gas flow and its properties will reach periodic or close to periodic steady state within two or three engine cycles, which is feasible to solve with today's computing power. In contrast, the temperature distribution inside the metal engine components will take many more engine cycles to achieve the periodic steady state, depending on thermal penetration depth [5,12] and thermal properties of the metal components, e.g., specific heat, thermal conductivity, and density. Running the KIVA code with conjugate heat transfer mode for so many engine cycles would require massive computing power.…”

“…For applications that account for multiple-medium domains, equivalent coefficients in Eqs. (5) and (6) must be used to represent the physics correctly [13]. To accurately model heat transfer across a multiple-medium problem, two constraints are applied at the CS.…”

“…A structured finite-volume method to model temperature distribution inside the metal engine components was previously developed and validated [5]. Further improvement had been added into the scheme, allowing it to model complex geometries such as the metal components inside the engine head.…”

A theoretical study on the heat transfer process in diesel engines

“…Other studies, such as [16], use the onedimensional codes in order to obtain wall temperatures as boundary conditions, in order to simplify the computational domain. Along with more computational power, more and more researchers have included both the bulk gas and the solid regions in the computational domain, which means that the wall temperatures are resolved in the CFD simulation [17][18][19][20][21][22][23].…”