Uncoupled CFD-FEA Methods for the Thermo-Structural Analysis of Turbochargers

Abstract

In turbocharger design, the accurate determination of thermally induced stresses is of particular importance for life cycle predictions. An accurate, transient, thermal finite element analysis (FEA) of turbocharger components requires transient conjugate heat transfer (CHT) analysis. However, due to the vastly different timescales of the heat transfer mechanisms in fluid and in solid states, unsteady CHT simulations are burdened by high computational costs. Hence, for design iterations, uncoupled CFD and FEA approaches are needed. The quality of the uncoupled thermal analysis depends on the local heat transfer coefficients (HTC) and reference fluid temperatures. In this paper, multiple CFD-FEA methods known from literature are implemented in a numerical model of a turbocharger. In order to describe the heat transfer and thermal boundary layer of the fluid, different definitions of heat transfer coefficients and reference fluid temperatures are investigated with regard to calculation time and accuracy. For the transient simulation of a long heating process, the combination of the CFD-FEA methods with the interpolation FEA approach is examined. Additionally, a structural-mechanical analysis is conducted. The results of the developed methods are evaluated against experimental data and the results of the extensive unsteady CHT numerical method.

Energy Evaluation of Synthesis Gas in a Turbocharger System Employing CFD Tools

“…Likewise, various studies have been developed applying CFD tools to analyze behaviors, that can hardly be measured or instrumented experimentally, so in works developed such as those of Ref. [13][14][15][16][17] they applied simulations by CFD means of estimating the energy performance of a turbocharger turbine system, comparing output variables at different mass flow rates among other factors.…”

Analysis and design of the gas generator multifunctional bulkhead considering the thermal and structural loads

“…Similar CFD-FEA coupled approach can be found in Refs. 10,11,16,17 In this paper the influence of other specific effects, such as erosion failure mechanisms, 18 hot corrosion, 19 oxidation, 8 wear, fouling, 20 thermal fatigue 9 and others are neglected due to two major reasons. First, the numerical model is already very complex and it demands considerable time and hardware resources.…”

Experimental and numerical investigation of the thermomechanical load on a turbine housing in a radial turbocharger

“…[4][5][6] This model can be designed via two approaches: heat flux is one approach, temperature and heat transfer coefficient is another. 7,8 Authors have developed new CFD analysis codes that can simultaneously predict the hot gas flowfield and the temperature field inside internally cooled configurations such as axial gas turbine blades. With this approach, temperatures and heat fluxes on the solid surfaces in contact with the moving fluid do not need to be specified since they are iteratively captured by the conjugate analysis code.…”

“…The second method involves shortening the heat transfer or cooling process of the model by reducing the specific heat capacity of the solid to an accelerating factor without an interpolation process. 8,10 The thermomechanical fatigue life of a component can be evaluated by solving the thermomechanical temperature and stress of the part. Thermomechanical temperature and strain (stress) simulations are solved by uncoupled or coupled methods; the uncoupled method requires manual control of iteration errors and the assessment of convergence results; it only focuses on the relationship between the core physical quantities in the physical field 2,8,11 The coupling solution can set the iteration error and automatically obtain the convergence result; we focus on the relationship between multiple or all physical quantities in the physical field.…”

“…8,10 The thermomechanical fatigue life of a component can be evaluated by solving the thermomechanical temperature and stress of the part. Thermomechanical temperature and strain (stress) simulations are solved by uncoupled or coupled methods; the uncoupled method requires manual control of iteration errors and the assessment of convergence results; it only focuses on the relationship between the core physical quantities in the physical field 2,8,11 The coupling solution can set the iteration error and automatically obtain the convergence result; we focus on the relationship between multiple or all physical quantities in the physical field. [12][13][14] The temperature field measurement of the turbocharger components requires a thermocouple to acquire the temperature at a point on the measured object.…”