scholarly journals Finite element analysis of a composite piston for a diesel aircraft engine

2019 ◽  
Vol 179 (4) ◽  
pp. 107-111
Author(s):  
Konrad PIETRYKOWSKI ◽  
Paweł MAGRYTA ◽  
Krzysztof SKIBA
Keyword(s):  
Heat Flux ◽  
Boundary Conditions ◽  
Mechanical Load ◽  
Aircraft Engine ◽  
Element Analysis ◽  
Mechanical Loads ◽  
Thermal Boundary Conditions ◽  
Piston Crown ◽  
Geometrical Dimensions ◽  
Abaqus Software

The article presents calculations of thermal and mechanical loads of the piston, consisting of two parts: steel and aluminum. The calculations were made using FEM in the Abaqus software. The piston is characterized by a split construction and was equipped with a cooling oil channel. The piston will be used in an aircraft diesel engine characterized by opposite piston movement. The presented geometry of the piston is the next of the ones being developed earlier and contains preliminary assumptions as to the size and main geometrical dimensions. The thermal boundary conditions of the simulation tests assumed defined areas of heat reception surface and heating of the piston by defining a temperature map on its crown. The results of these studies were presented in the form of temperature distribution and heat flux on the surface of the tested element. The strength boundary conditions assumed a mechanical load in the form of pressure resulting from the pressure in the combustion chamber applied to the piston crown surface and the opposite pressure defined on the support at the surface of contact between the piston and the piston pin. The results of these tests were presented in the form of stress distribution on the surface of the tested element. As a result of the analyses carried out, the results constituting the basis for further modernization of the piston geometry were obtained.

Thermal Barrier Coating on IC Engine Piston to Improve Engine Efficiency

2017 ◽  
Vol 9 (1) ◽  
pp. 47 ◽  
Author(s):  
Balbheem Kamanna ◽  
Bibin Jose ◽  
Ajay Shamrao Shedage ◽  
Sagar Ganpat Ambekar ◽  
Rajesh Somnath Shinde ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Heat Flux ◽  
Thermal Stresses ◽  
Mechanical Efficiency ◽  
Project Work ◽  
Element Analysis ◽  
Ic Engine ◽  
Engine Efficiency ◽  
Piston Crown ◽  
Barrier Coating

The piston is considered as most important part of I.C engine. High temperature produced in an I.C engine may contribute to high thermal stresses. Without appropriate heat transfer mechanism, the piston crown would operate ineffectively which reduce life cycle of piston and hence mechanical efficiency of engine. The literature survey shows that ideal piston consumes heat produced by burnt gases resulting in decrease of Engine overall Efficiency. In this project work an attempt is made to redesign piston crown using TBC on piston surface and to study its Performance. A 150 cc engine is considered and TBC material with different thickness is coated on the piston. 3D modeling of the piston geometry is done 3D designing software Solidworks2015. Finite Element analysis is used to calculate temperature and heat flux distribution on piston crown. The result shows TBC as a coating on piston crown surface reduces the heat transfer rate within the piston and that will results in increase of engine efficiency. Results also show that temperature and heat flux decreases with increase in coating thickness of YSZ.

scholarly journals The asymptotic equivalence of fixed heat flux and fixed temperature thermal boundary conditions for rapidly rotating convection

2015 ◽  
Vol 784 ◽  
Author(s):  
Michael A. Calkins ◽  
Kevin Hale ◽  
Keith Julien ◽  
David Nieves ◽  
Derek Driggs ◽  
...  
Keyword(s):  
Heat Flux ◽  
Boundary Conditions ◽  
Boundary Layers ◽  
Layer Structure ◽  
Plane Layer ◽  
Order System ◽  
Leading Order ◽  
Fixed Temperature ◽  
Rotating Convection ◽  
Thermal Boundary Conditions

The influence of fixed temperature and fixed heat flux thermal boundary conditions on rapidly rotating convection in the plane layer geometry is investigated for the case of stress-free mechanical boundary conditions. It is shown that whereas the leading-order system satisfies fixed temperature boundary conditions implicitly, a double boundary layer structure is necessary to satisfy the fixed heat flux thermal boundary conditions. The boundary layers consist of a classical Ekman layer adjacent to the solid boundaries that adjust viscous stresses to zero, and a layer in thermal wind balance just outside the Ekman layers that adjusts the normal derivative of the temperature fluctuation to zero. The influence of these boundary layers on the interior geostrophically balanced convection is shown to be asymptotically weak, however. Upon defining a simple rescaling of the thermal variables, the leading-order reduced system of governing equations is therefore equivalent for both boundary conditions. These results imply that any horizontal thermal variation along the boundaries that varies on the scale of the convection has no leading-order influence on the interior convection, thus providing insight into geophysical and astrophysical flows where stress-free mechanical boundary conditions are often assumed.

Effects of Nanoparticle Migration on Water/Alumina Nanofluid Flow Inside a Horizontal Annulus with a Moving Core

2014 ◽  
Vol 31 (3) ◽  
pp. 291-305 ◽  
Author(s):  
A. Malvandi ◽  
D. D. Ganji
Keyword(s):  
Heat Transfer ◽  
Heat Flux ◽  
Boundary Conditions ◽  
Heat Transfer Rate ◽  
Transfer Rate ◽  
Outer Wall ◽  
Constant Heat Flux ◽  
Constant Heat ◽  
Thermal Boundary Conditions ◽  
Alumina Nanofluid

AbstractThe present study is a theoretical investigation of the laminar flow and convective heat transfer of water/alumina nanofluid inside a horizontal annulus with a streamwise moving inner cylinder. A modified, two-component, four-equation, nonhomogeneous equilibrium model is employed for the alumina/water nanofluid, which fully accounts for the effect of the nanoparticle volume fraction distribution. To determine the effects of thermal boundary conditions on the migration of the nanoparticles, two cases are considered: constant heat flux at the outer wall with an adiabatic inner wall (Case A) and constant heat flux at the inner wall with an adiabatic outer wall (Case B). The numerical results indicate that the thermal boundary conditions at the pipe walls significantly affect the nanoparticle distribution, particularly in cases where the ratio of Brownian motion to thermophoretic diffusivities is small. Moreover, increasing the velocity of the moving inner cylinder reduces the heat transfer rate for Case A. Conversely, in Case B, the movement of the inner cylinder enhances the heat transfer rate, and anomalous heat transfer enhancement occurs when the thermophoretic force is dominant (in larger nanoparticles).

scholarly journals Investigation of Mechanical Loads Distribution for the Process of Generating Gear Grinding

2021 ◽  
Vol 5 (1) ◽  
pp. 13
Author(s):  
Patricia de Oliveira Teixeira ◽  
Jens Brimmers ◽  
Thomas Bergs
Keyword(s):  
Heat Flux ◽  
Prediction Models ◽  
Mechanical Load ◽  
Frictional Heating ◽  
Formation Mechanisms ◽  
Workpiece Material ◽  
Influence Of Process Parameters ◽  
Mechanical Loads ◽  
Single Grain ◽  
Generating Grinding

In grinding, interaction between the workpiece material and rotating abrasive tool generates high thermo-mechanical loads in the contact zone. If these loads reach critically high values, workpiece material properties deteriorate. To prevent the material deterioration, several models for thermomechanical analysis of grinding processes have been developed. In these models, the source of heat flux is usually considered as uniform in the temperature distribution calculation. However, it is known that heat flux in grinding is generated from frictional heating as well as plastic deformation during the interaction between workpiece material and each grain from the tool. To consider these factors in a future coupled thermomechanical model specifically for the process of gear generating grinding, an investigation of the mechanical load distribution during interaction between grain and workpiece material considering the process kinematics is first required. This work aims to investigate the influence of process parameters as well as grain shape on the distribution of the mechanical loads along a single-grain in gear generating grinding. For this investigation, an adaptation of a single-grain energy model considering the chip formation mechanisms is proposed. The grinding energy as well as normal force can be determined either supported by measurements or solely based on prediction models.

Effects of thermal boundary conditions on rotating Rayleigh-Bénard convection with implications on geophysical and astrophysical systems

2021 ◽  
Author(s):  
Janet Peifer ◽  
Onno Bokhove ◽  
Steve Tobias
Keyword(s):  
Boundary Condition ◽  
Heat Flux ◽  
Boundary Conditions ◽  
Biot Number ◽  
Thermal Flux ◽  
Thermal Boundary Condition ◽  
Actual Condition ◽  
Fixed Temperature ◽  
Thermal Boundary Conditions ◽  
Core Dynamics

<p>Rayleigh-Bénard convection (RBC) is a fluid phenomenon that has been studied for over a century because of its utility in simplifying very complex physical systems. Many geophysical and astrophysical systems, including planetary core dynamics and components of weather prediction, are modeled by including rotational forcing in classic RBC. Our understanding of these systems is confined by experimental and numerical limits, as well as theoretical assumptions. </p><p>The role of thermal boundary condition choice on experimental studies of geophysical and astrophysical systems has been often been overlooked, which could account for some lack of agreement between experimental and numerical models as well as the actual flows. The typical thermal boundary conditions prescribed at the top and the bottom of a convection system are fixed temperature conditions, despite few real geophysical systems being bounded with a fixed temperature. A constant heat flux is generally more applicable for real large-scale geophysical systems. However, when this condition is applied in numerical systems, the lack of fixed temperature can cause a temperature drift. In this study, we seek to minimize temperature drifting by applying a fixed temperature condition on one boundary and a fixed thermal flux on the other.</p><p>Experimental boundary conditions are also often assumed to be a fixed temperature. However, the actual condition is determined by the ratio of the height and thermal conductivity of the boundary material to that of the contained fluid, known as the Biot number. The relationship between the Biot number and thermal boundary condition behavior is defined by the Robin, or 'thin-lid', boundary condition such that low Biot number boundaries are essentially fixed thermal flux and high Biot number boundaries are essentially fixed temperature. </p><p>This study seeks to strengthen the link between numerical and experimental models and geophysical flows by investigating the effects of thermal boundary conditions and their relationship to real-world processes. Both fixed temperature and fixed flux boundary conditions are considered. In addition, the Robin boundary condition is studied at a range of Biot numbers spanning from fixed temperature to fixed flux, allowing intermediate conditions to be investigated. Each system is studied at increasingly rapid rotation rates, corresponding to decreasing Ekman numbers as low as Ek=10<sup>-5</sup> Heat transport is analyzed using the Nusselt number, Nu, and the form of the solution is described by the number of convection rolls and time-dependency. Further investigations will analyze Nu and fluid movement within a system with heterogeneous heat flux condition on the  sidewall boundary conditions, which is useful in the study of planetary core dynamics. The results of this study have implications for improvements in modeling geophysical systems both experimentally and numerically. </p>

Alternative and Relevant Representation to Heat Transfer Coefficient for Modeling the Heat Transfer Between a Fluid and a Non-Isothermal Wall in Transient Regime

2010 ◽  
Author(s):  
Benjamin Remy ◽  
Alain Degiovanni
Keyword(s):  
Heat Transfer ◽  
Heat Flux ◽  
Heat Transfer Coefficient ◽  
Steady State ◽  
Boundary Conditions ◽  
Transfer Coefficient ◽  
Flat Plate ◽  
Temperature Difference ◽  
Interfacial Heat Transfer ◽  
Thermal Boundary Conditions

This paper deals with the relevant model that can be proposed for modeling the interfacial heat transfer between a fluid and a wall in the case of space and time varying thermal boundary conditions. Usually, for a constant and uniform heat transfer (unidirectional steady-state regime), the problem can be solved introducing a heat transfer coefficient h, uniform in space and constant in time that linearly links the surface heat flux and the temperature difference between the wall temperature Tw and an equivalent fluid temperature Tf. The problem we consider in this work concerns the heat transfer between a steady-state fluid flow and a wall submitted to a transient and non uniform thermal solicitations, as for instance a steady-state flow on a flat plate submitted to a transient and space reduced heat flux. We will show that the more interesting representation for describing the interfacial heat transfer is not to define as usually done a non-uniform and variable heat transfer coefficient h(x,t) because as it depends on the thermal boundary conditions, it is not really intrinsic. We propose an alternative approach, which consists in introducing a generalized impedance Z(ω,p) that links in space and time domain the heat flux and the temperature difference through a double convolution product instead of a scalar product. After the presentation of the general problem, the simple case of a stationary piston flow that can be solved analytically will be considered for validation both in thermal steady-state and transient regimes. To conclude and show the interest of our approach, a comparison between a global approach and a numerical simulation in a more complex and realistic case taking into account the thermal coupling with a flat plate will be presented.

Analysis of the Thermal Behavior of a Ball Screw Based on Simulation and Experimental Investigation

2014 ◽  
Vol 577 ◽  
pp. 140-144
Author(s):  
Zi Han Li ◽  
Kai Guo Fan ◽  
Jian Guo Yang
Keyword(s):  
Finite Element Analysis ◽  
Experimental Investigation ◽  
Finite Element ◽  
Boundary Conditions ◽  
Thermal Behavior ◽  
Temperature Variation ◽  
Ball Screw ◽  
Variation Pattern ◽  
Element Analysis ◽  
Thermal Boundary Conditions

Thermal expansion of ball screw system affects the machining accuracy of machine tools significantly. The objective of this paper is to analyze the thermal behavior and predict the temperature variation pattern of a ball screw based on finite element analysis and experimental investigation. Wireless temperature sensors are used to monitor the temperature variation of the ball screw system under different thermal conditions during both the warm-up and cooldown phases, so as to investigate its temperature variation pattern. Then an exponential algorithm is proposed to analyze and predict the temperature variation of the ball screw based on finite element analysis, and the actual thermal boundary conditions of the ball screw system are exactly defined according to the proposed algorithm and the experimental results. Finally, it was found that the simulation based on the thermal boundary conditions identified herein could match quite well with the experimental results.

Steady Thermochromic Liquid Crystal Technique for Study of Conjugate Heat Transfer Problems

2003 ◽  
Author(s):  
C. J. Douglass ◽  
J. S. Kapat ◽  
E. Divo ◽  
A. J. Kassab ◽  
J. Tapley ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Heat Flux ◽  
Liquid Crystal ◽  
Boundary Conditions ◽  
Surface Heat Flux ◽  
Conjugate Heat Transfer ◽  
Surface Heat ◽  
Test Block ◽  
Thermochromic Liquid Crystal ◽  
Thermal Boundary Conditions

This paper presents a steady measurement technique based on thermochromic liquid crystals (TLC) that can be used for study of conjugate heat transfer. In contrast to the more commonly used transient thermochromic liquid crystal technique, this technique requires steady-state experiments, and eliminates some of the limitations of the transient version at the cost of measurements or knowledge of thermal conditions all surfaces and increased computations for data reduction. This technique requires that thermal boundary conditions be known or measured on all internal or external surfaces of the test block. All surfaces that are exposed to external air flow are coated with a broad-bandwidth TLC. The thermal boundary conditions are then sent to a steady conduction solver that involves the boundary element method (BEM) and an inverse problem approach (BEM/IP). This combined BEM/IP approach minimizes the effects of random experimental error in measured data and calculates surface heat flux, from which the intended convective heat flux coefficients can then be calculated. The technique is applied to a prismatic stainless steel block exposed to warm air flows on three sides — an arrangement that has been used often to simulate flow through a blade tip gap. It is found that an in-situ pixel-by-pixel calibration of TLC hue vs temperature is needed in order to obtain reasonable accuracy. A calibration-curve-fit uncertainty of better than 0.4°C (at 95% confidence level) was obtained in this process. In the actual experiments, conjugate heat transfer was set up by passing cold water through three cooling channels that span the test block. Once the experiments are completed and the TLC colors are converted to surface temperature distributions, the BEM/IP approach is used to obtain surface heat flux distributions, and then distribution of heat transfer coefficients.

Alternative Solutions for Longitudinal Fins of Rectangular, Trapezoidal, and Concave Parabolic Profiles

2006 ◽  
Author(s):  
A. Aziz
Keyword(s):  
Thermal Analysis ◽  
Heat Flux ◽  
Boundary Conditions ◽  
Fixed Temperature ◽  
Thermal Boundary Conditions ◽  
Convective Fin ◽  
The Relationship ◽  
Alternative Solutions ◽  
Dimensionless Heat Flux ◽  
Dimensionless Heat

The traditional thermal analysis of fins is based on the assumption of specified thermal boundary conditions at the base and tip of the fin. For situations when the fin base is in contact with a fluid experiencing condensation and the fin is required to remove the energy released by the fluid, the base is subjected to two boundary conditions: a fixed temperature and a fixed heat flux. This paper develops solutions for the temperature distribution in the fins under these conditions. Solutions are provided for rectangular, trapezoidal, and concave parabolic (finite tip thickness). Results illustrating the relationship between the dimensionless heat flux, the fin parameter, and dimensionless tip temperature are provided for all three geometries. The case of convective fin tip is also considered and lead to a relationship between the dimensionless heat flux, the fin parameter, and the Biot number at the tip. The results presented here provide tools that not only complement the traditional analyses but are believed to have more direct relevance for fin designers.

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