Design and Heat Transfer Analysis of Automotive Disc Brakes

2003 ◽  
Author(s):  
J. Jancirani ◽  
S. Chandrasekaran ◽  
P. Tamilporai
Keyword(s):  
Heat Transfer ◽  
Thermal Loading ◽  
Operating Conditions ◽  
Heat Transfer Analysis ◽  
Disc Brake ◽  
Braking System ◽  
Wide Range ◽  
Disc Brakes ◽  
Construction Operation ◽  
Drum Brakes

In the recent scenario of braking system for automobiles, disc brake takes up a wide range of applications, because of its simplicity in construction, operation and not self energizing as in the case of drum brakes. Since the disc brakes takes up a wide range of application, it is essential to ensure the reliable function of the braking system under varied operating conditions. The reliable function of the disc brake system is purely depends on the system based design. In this work, a linear regression technique is used for the optimal design of the disc brake rotor for varied operating conditions. Various forces involved during braking, energy generated during braking and the corresponding effective stopping distances were also calculated using appropriate governing relations and equations. In the varied operating conditions, the heat energy generated during braking should be driven away form the working surfaces of the components. To analyze this thermal loading and cooling phenomenon, a conventional convective heat transfer approach was also formulated and developed in this work. The analytical findings of the above approaches are demonstrated at the end and it is found to be quite satisfactory.

scholarly journals Numerical Study of Heat Transfer and Speed Air Flow on Performance of an Auto-Ventilated Disc Brake

Fluids ◽  
2021 ◽  
Vol 6 (4) ◽  
pp. 160
Author(s):  
R. A. García-León ◽  
N. Afanador-García ◽  
J. A. Gómez-Camperos
Keyword(s):  
Heat Transfer ◽  
Working Conditions ◽  
Heat Dissipation ◽  
Numerical Study ◽  
Operating Conditions ◽  
Simple Type ◽  
Disc Brake ◽  
Ansys Software ◽  
Braking System ◽  
Disc Brakes

In the braking system, the heat dissipation generated by the friction between the disc and pad should be evacuated as quickly as possible. In this work, five common different automotive disc brakes were studied through mathematical theories of heat transfer and numerical methods using the ANSYS software. In addition, a direct comparison between experimental, theoretical, and simulation values found in the open literature was performed to propose a disc brake with an improved geometry in terms of dissipation of heat transfer. The numerical results were considered to propose two possible solutions of disc brake geometries using N-38 ventilation blades used in aeronautic engineering. An improvement in temperature dissipation was achieved by approximately 23.8% compared to the five geometries analyzed with a simple type N-38 ventilation blade. The heat dissipation in the brakes strongly depends on the geometry of the disc, the geometry of the blades, the material from which it is manufactured, the material of the pad, the weight of the vehicle, and the operating conditions, as can be verified with mathematical calculations and experiments. The results obtained demonstrate that the discs can be used effectively in extreme working conditions (80 km/h and 33°C), without affecting the safety of the occupants and the braking system.

A Physics-Based Heat Transfer Analysis for Aerospace Ball Thrust Bearings

2005 ◽  
Author(s):  
Sean McCutchan ◽  
Roger M. Barnsby
Keyword(s):  
Heat Transfer ◽  
Thermal Characteristics ◽  
New Physics ◽  
Operating Conditions ◽  
Heat Transfer Analysis ◽  
Critical Parameters ◽  
Flow Equations ◽  
Bearing Ring ◽  
Lubricant Property ◽  
Wide Range

Component temperatures have a significant influence on ball bearing life and durability. Critical parameters such as internal clearance, contact stress and oil film thickness are influenced by the thermal characteristics of a bearing. Previous heat transfer analyses that predict bearing ring temperatures have been typically based on empirical data. A new physics-based analysis has been developed which is derived from fundamental heat transfer and fluid flow equations. Gyroscopic torque and churning forces are balanced by oil shearing contact traction, using recent developments in new life theory [1] and lubricant property models [2]. Bearing ring temperatures and heat generation calculated by the new analysis have been successfully correlated with test data over a wide range of bearing sizes and operating conditions.

Investigation on Thermal Loading of Disc Brakes: An Approach

2003 ◽  
Author(s):  
J. Jancirani ◽  
S. Chandrasekaran ◽  
P. Tamilporai
Keyword(s):  
Thermal Analysis ◽  
Thermal Loading ◽  
Three Dimensional ◽  
Lumped Parameter Model ◽  
Disc Brake ◽  
Thermal Distortion ◽  
Lumped Parameter ◽  
Wide Range ◽  
Disc Brakes ◽  
Three Dimensional Models

In the wide range of braking speed, the disc brakes are subjected to temperature variation and thermal loading. Different modelling approaches ranging from a simple lumped parameter model to complex three-dimensional models are available for the thermal analysis of the disc brakes. Based on the review of the above models, a model has been developed and formulated for the analysis of thermal loading of disc brake. The developed model is proposed to couple with a model for the thermal distortion of disc brake. It is also proposed to conduct the necessary experiments and thermal analysis to validate the results obtained from the synthesized analysis.

Unsteady Conjugate Heat Transfer Investigation of a Multistage Steam Turbine in Warm-Keeping Operation With Hot Air

2018 ◽  
Author(s):  
Piotr Łuczyński ◽  
Dennis Toebben ◽  
Manfred Wirsum ◽  
Wolfgang F. D. Mohr ◽  
Klaus Helbig
Keyword(s):  
Heat Transfer ◽  
Conjugate Heat Transfer ◽  
Flow Patterns ◽  
Operating Conditions ◽  
Angle Of Incidence ◽  
Time Step ◽  
Hot Air ◽  
Wide Range ◽  
Vortex Systems ◽  
Operating Points

In recent decades, the rising share of commonly subsidized renewable energy especially affects the operational strategy of conventional power plants. In pursuit of flexibility improvements, extension of life cycle, in addition to a reduction in start-up time, General Electric has developed a product to warm-keep high/intermediate pressure steam turbines using hot air. In order to optimize the warm-keeping operation and to gain knowledge about the dominant heat transfer phenomena and flow structures, detailed numerical investigations are required. Considering specific warm-keeping operating conditions characterized by high turbulent flows, it is required to conduct calculations based on time-consuming unsteady conjugate heat transfer (CHT) simulations. In order to investigate the warm-keeping process as found in the presented research, single and multistage numerical turbine models were developed. Furthermore, an innovative calculation approach called the Equalized Timescales Method (ET) was applied for the modeling of unsteady conjugate heat transfer (CHT). The unsteady approach improves the accuracy of the stationary simulations and enables the determination of the multistage turbine models. In the course of the research, two particular input variables of the ET approach — speed up factor (SF) and time step (TS) — have been additionally investigated with regard to their high impact on the calculation time and the quality of the results. Using the ET method, the mass flow rate and the rotational speed were varied to generate a database of warm-keeping operating points. The main goal of this work is to provide a comprehensive knowledge of the flow field and heat transfer in a wide range of turbine warm-keeping operations and to characterize the flow patterns observed at these operating points. For varying values of flow coefficient and angle of incidence, the secondary flow phenomena change from well-known vortex systems occurring in design operation (such as passage, horseshoe and corner vortices) to effects typical for windage, like patterns of alternating vortices and strong backflows. Furthermore, the identified flow patterns have been compared to vortex systems described in cited literature and summarized in the so-called blade vortex diagram. The comparison of heat transfer in the form of charts showing the variation of the Nusselt-numbers with respect to changes in angle of incidence and flow coefficients at specific operating points is additionally provided.

scholarly journals Cooling Performance of Arrays of Vibrating Cantilevers

2009 ◽  
Vol 131 (11) ◽  
Author(s):  
Mark Kimber ◽  
Suresh V. Garimella
Keyword(s):  
Heat Transfer ◽  
Thermal Performance ◽  
Vibration Amplitude ◽  
Past Research ◽  
Resonant Mode ◽  
Operating Conditions ◽  
Infrared Thermal Imaging ◽  
Practical Applications ◽  
Wide Range ◽  
Piezoelectric Fans

Piezoelectric fans are vibrating cantilevers actuated by a piezoelectric material and can provide heat transfer enhancement while consuming little power. Past research has focused on feasibility and performance characterization of a single fan, while arrays of such fans, which have important practical applications, have not been widely studied. This paper investigates the heat transfer achieved using arrays of cantilevers vibrating in their first resonant mode. This is accomplished by determining the local convection coefficients due to the two piezoelectric fans mounted near a constant heat flux surface using infrared thermal imaging. The heat transfer performance is quantified over a wide range of operating conditions, including vibration amplitude (7.5–10 mm), distance from heat source (0.01–2 times the fan amplitude), and pitch between fans (0.5–4 times the amplitude). The convection patterns observed are strongly dependent on the fan pitch, with the behavior resembling a single fan for small fan pitch and two isolated fans at a large pitch. The area-averaged thermal performance of the fan array is superior to that of a single fan, and correlations are developed to describe this enhancement in terms of the governing parameters. The best thermal performance is obtained when the fan pitch is 1.5 times its vibration amplitude.

Heat Transfer Analysis of Human Cell Culture Under RF Exposure

2005 ◽  
Author(s):  
Muhammad Khalid ◽  
Chenn Zhou ◽  
Ashish Bassi ◽  
San Ming Wang ◽  
Howard Gerber ◽  
...  
Keyword(s):  
Gene Expression ◽  
Heat Transfer ◽  
Electric Field ◽  
Fluid Dynamic ◽  
Operating Conditions ◽  
Heat Transfer Analysis ◽  
Heat Shock Gene ◽  
Exposure System ◽  
Finite Element Software ◽  
Rf Exposure

A 2.45 GHz radio frequency (RF) exposure system was designed and used to study the RF effects on the genome-wide gene expression in cultured human cells. In this system, a T-25 culture flask, which contains 10 × 106 cells in a 10ml medium, is placed in a WR 340 waveguide. The waveguide serves as an environmental chamber. The source is a pulsed magnetron for obtaining a high electric field with the specific absorption rate (SAR) at approximately 10 W/kg. In order to ensure the non-thermal effect, the system was designed to maintain a temperature of 37°C. In this research, the heat transfer analysis of the system was conducted using the computational fluid dynamic (CFD) software FLUENT® coupled with the finite element software, High Frequency Structural Simulation (HFSS) by Ansoft. The electric field was first analyzed by using HFSS to calculate the SAR distribution as a heat source input for CFD calculations. The fluid flow and temperature distributions within the flask were then analyzed using FLUENT®. The results were validated experimentally by measuring the temperatures with fluoroptic thermometer probes as well as by examining the level of heat shock gene expression. These results provide useful information for a better understanding and controlling of the operating conditions of the system.

A Natural Convection Fin with a Solution-Determined Nonmonotonically Varying Heat Transfer Coefficient

1981 ◽  
Vol 103 (2) ◽  
pp. 218-225 ◽  
Author(s):  
E. M. Sparrow ◽  
S. Acharya
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Natural Convection ◽  
Transfer Coefficient ◽  
First Principles ◽  
Numerical Solutions ◽  
Flow Direction ◽  
Operating Conditions ◽  
Fluid Temperature ◽  
Wide Range

A conjugate conduction-convection analysis has been made for a vertical plate fin which exchanges heat with its fluid environment by natural convection. The analysis is based on a first-principles approach whereby the heat conduction equation for the fin is solved simultaneously with the conservation equations for mass, momentum, and energy in the fluid boundary layer adjacent to the fin. The natural convection heat transfer coefficient is not specified in advance but is one of the results of the numerical solutions. For a wide range of operating conditions, the local heat transfer coefficients were found not to decrease monotonically in the flow direction, as is usual. Rather, the coefficient decreased at first, attained a minimum, and then increased with increasing downstream distance. This behavior was attributed to an enhanced buoyancy resulting from an increase in the wall-to-fluid temperature difference along the streamwise direction. To supplement the first-principles analysis, results were also obtained from a simple adaptation of the conventional fin model.

One-Dimensional Zonal Model for the Unsteady Heat Transfer Analysis in an Open Volumetric Air Receiver

2020 ◽  
Vol 13 (1) ◽  
Author(s):  
Gurveer Singh ◽  
Vishwa Deepak Kumar ◽  
Laltu Chandra ◽  
R. Shekhar ◽  
P. S. Ghoshdastidar
Keyword(s):  
Heat Transfer ◽  
High Heat ◽  
Operating Conditions ◽  
Heat Transfer Analysis ◽  
Transfer Model ◽  
High Heat Flux ◽  
Unsteady Heat Transfer ◽  
Volumetric Heating ◽  
One Dimensional ◽  
Zonal Model

Abstract The open volumetric air receiver (OVAR)-based central solar thermal systems provide air at a temperature > 1000 K. Such a receiver is comprised of porous absorbers, which are exposed to a high heat-flux > 800 Suns (1 Sun = 1 kW/m2). A reliable assessment of heat transfer in an OVAR is necessary to operate such a receiver under transient conditions. Based on a literature review, the need for developing a comprehensive, unsteady, heat transfer model is realized. In this paper, a seven-equations based, one-dimensional, zonal model is deduced. This includes heat transfer in porous absorber, primary-air, return-air, receiver casing, and their detailed interaction. The zonal model is validated with an inhouse experiment showing its predictive capability, for unsteady and steady conditions, within the reported uncertainty of ±7%. The validated model is used for investigating the effect of operating conditions and absorber geometry on the thermal performance of an absorber. Some of the salient observations are (a) the maximum absorber porosity of 70–90% may be preferred for non-volumetric and volumetric-heating conditions, (b) the minimum air-return ratio should be 0.7, and (c) the smallest gap to absorber-length ratio of 0.2 should suffice. Finally, suggestions are provided for extending the model.

Thermal–Hydraulic Performance Analysis of a Convergent Double Pipe Heat Exchanger

2019 ◽  
Vol 141 (5) ◽  
Author(s):  
Ahmed T. Al-Sammarraie ◽  
Kambiz Vafai
Keyword(s):  
Heat Transfer ◽  
Heat Exchanger ◽  
Hydraulic Performance ◽  
Operating Conditions ◽  
Contraction Ratio ◽  
Wide Range ◽  
Prandtl Numbers ◽  
Double Pipe ◽  
The Impact ◽  
Pipe Heat

The present investigation proposes an innovative convergent double pipe heat exchanger (C-DPHE). A two-dimensional (2D) axisymmetric heat transfer model with counterflow is employed to analyze the thermal and hydraulic performance of this configuration numerically. The impact of convergence in the flow direction, using a wide range of contraction ratio (Cr), is explored. The effect of Reynolds and Prandtl numbers on the flow and heat transfer is addressed, as well. The model results were validated with available data from the literature, and an excellent agreement has been confirmed. In general, the findings of the present study indicate that increasing the contraction ratio increases heat transfer and pressure drop in the C-DPHE. Moreover, this configuration has a prominent and sustainable performance, compared to a conventional double pipe heat exchanger (DPHE), with an enhancement in heat transfer rate up to 32% and performance factor (PF) higher than one. Another appealing merit for the C-DPHE is that it is quite effective and functional at low Reynolds and high Prandtl numbers, respectively, since no high-operating pumping power is required. Further, the optimal operating conditions can be established utilizing the comprehensive information provided in this work.

Predicting Heat Transfer From Unsteady Synthetic Jets

2012 ◽  
Vol 134 (8) ◽  
Author(s):  
Mehmet Arik ◽  
Tunc Icoz
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Transfer Coefficient ◽  
Jet Impingement ◽  
Synthetic Jet ◽  
Synthetic Jets ◽  
Operating Conditions ◽  
Small Scale ◽  
Wide Range ◽  
The Heat Transfer Coefficient

Synthetic jets are piezo-driven, small-scale, pulsating devices capable of producing highly turbulent jets formed by periodic entrainment and expulsion of the fluid in which they are embedded. The compactness of these devices accompanied by high air velocities provides an exciting opportunity to significantly reduce the size of thermal management systems in electronic packages. A number of researchers have shown the implementations of synthetic jets on heat transfer applications; however, there exists no correlation to analytically predict the heat transfer coefficient for such applications. A closed form correlation was developed to predict the heat transfer coefficient as a function of jet geometry, position, and operating conditions for impinging flow based on experimental data. The proposed correlation was shown to predict the synthetic jet impingement heat transfer within 25% accuracy for a wide range of operating conditions and geometrical variables.

Sign in / Sign up

Export Citation Format

Share Document