Cooling Mechanisms in a Rotating Brake Disc With a Wire-Woven-Bulk Diamond Cellular Core

2021 ◽  
Vol 13 (4) ◽  
Author(s):  
Michael D. Atkins ◽  
Frank W. Kienhöfer ◽  
Kiju Kang ◽  
Tian Jian Lu ◽  
Tongbeum Kim
Keyword(s):  
Heat Transfer ◽  
Surface Area ◽  
Thermal Dissipation ◽  
Brake Disc ◽  
Thermochromic Liquid Crystal ◽  
Heavy Vehicles ◽  
Image Velocimetry ◽  
Recirculation Zones ◽  
Bulk Diamond ◽  
End Wall

Abstract Thermofluidic behaviors governing the enhanced cooling performance of the wire-woven-bulk diamond (WBD) cored brake disc in comparison with the conventional pin-finned brake disc used on heavy vehicles were characterized experimentally. For each type of brake disc, detailed internal thermofluidic data of the two rotating brake discs were obtained using transient thermochromic liquid crystal (TLC) for end-wall heat transfer and particle image velocimetry (PIV) for the inflow field. The results demonstrate that the pin-finned brake disc exhibits a circumferentially periodic curved inline-like passage flow and large dead flow regions, with strong recirculation that reduces its thermal dissipation performance. The cooling advantage of the WBD core is primarily attributed to the combination of enlarged heat transfer surface area (both end-wall and core) and greater utilization of the larger surface due to favorable fluidic behavior developed from the WBD topology. The internal WBD core has approximately three times the surface density of the pin-finned disc which, in combination with the smaller and weaker recirculation zones, leads to more effective usage of the available core surface area for thermal dissipation. The aerodynamic anisotropy of the WBD core induced by its topological anisotropy causes a globally irregular thermofluidic distribution in the brake disc.

Boundary Layer Influence on the Unsteady Horseshoe Vortex Flow and Surface Heat Transfer

2007 ◽  
Author(s):  
D. R. Sabatino ◽  
C. R. Smith
Keyword(s):  
Heat Transfer ◽  
Boundary Layer ◽  
Bluff Body ◽  
Leading Edge ◽  
Horseshoe Vortex ◽  
Surface Heat ◽  
Wall Region ◽  
Thermochromic Liquid Crystal ◽  
Surface Heat Transfer ◽  
End Wall

The spatial-temporal flow-field and associated surface heat transfer within the leading edge, end-wall region of a bluff body were examined using both particle image velocimetry and thermochromic liquid crystal temperature measurements. The horseshoe vortex system in the end-wall region is mechanistically linked to the upstream boundary layer unsteadiness. Hairpin vortex packets, associated with turbulent boundary layer bursting behavior, amalgamate with the horseshoe vortex resulting in unsteady strengthening and streamwise motion. The horseshoe vortex unsteadiness exhibits two different natural frequencies: one associated with the transient motion of the horseshoe vortex, and the other with the transient surface heat transfer. Comparable unsteadiness occurs in the end-wall region of the more complex airfoil geometry of a linear turbine cascade. To directly compare the horseshoe vortex behavior around a turning airfoil to that of a simple bluff body, a length scale based on the maximum airfoil thickness is proposed.

The Role of Secondary Flows and Separation in Convective Heat Transfer in a Rotating Radial Vane Brake Disc

2021 ◽  
Author(s):  
Michael. D Atkins ◽  
F.W. Kienhofer ◽  
Tian Jian Lu ◽  
Se-Myong Chang ◽  
Tongbeum Kim
Keyword(s):  
Heat Transfer ◽  
Convective Heat Transfer ◽  
Convective Heat ◽  
Suction Side ◽  
Secondary Flows ◽  
Brake Disc ◽  
Rotating Speed ◽  
Flow Mixing ◽  
End Wall ◽  
First Time

Abstract This study presents, for the first time, distributions of local internal temperature and convective heat transfer in a rotating radial vane brake disc and explains mechanisms in conjunction with secondary flows and flow separation within its ventilated coolant passages. In particular, variations of radial, circumferential (vane-to-vane) and axial (inboard-to-outboard) heat transfer on internal end-wall surfaces, and their alteration due to varying number of radial vanes and rotating speed are experimentally detailed. It has been demonstrated that conventional ventilated radial brake discs where the air inflow is drawn from the inboard face are likely to suffer substantial axial variations of temperature and heat transfer between the inboard and outboard discs, which possibly exacerbates thermal distortion (i.e., coning). Further, for a typical number of vanes (i.e., 36 vanes) used on automobiles, internal thermal distributions are highly non-uniform. However, the thermal end-wall uniformity improves considerably as the number of vanes is increased to say 72 vanes. Specifically, as the number of vanes is increased, secondary flow mixing enhances overall convective heat transfer and improves thermal uniformity. In contrast, separation causes large end-wall thermal non-uniformities in radial and circumferential distributions between the pressure side and the suction side of radial vanes. This effect nonetheless also decreases as the number of vanes is increased.

Boundary Layer Influence on the Unsteady Horseshoe Vortex Flow and Surface Heat Transfer

2008 ◽  
Vol 131 (1) ◽  
Author(s):  
D. R. Sabatino ◽  
C. R. Smith
Keyword(s):  
Heat Transfer ◽  
Boundary Layer ◽  
Bluff Body ◽  
Leading Edge ◽  
Horseshoe Vortex ◽  
Surface Heat ◽  
Wall Region ◽  
Thermochromic Liquid Crystal ◽  
Surface Heat Transfer ◽  
End Wall

The spatial-temporal flow field and associated surface heat transfer within the leading edge, end-wall region of a bluff body were examined using both particle image velocimetry and thermochromic liquid crystal temperature measurements. The horseshoe vortex system in the end-wall region is mechanistically linked to the upstream boundary layer unsteadiness. Hairpin vortex packets, associated with turbulent boundary layer bursting behavior, amalgamate with the horseshoe vortex resulting in unsteady strengthening and streamwise motion. The horseshoe vortex unsteadiness exhibits two different natural frequencies: one associated with the transient motion of the horseshoe vortex and the other with the transient surface heat transfer. Comparable unsteadiness occurs in the end-wall region of the more complex airfoil geometry of a linear turbine cascade. To directly compare the horseshoe vortex behavior around a turning airfoil to that of a simple bluff body, a length scale based on the maximum airfoil thickness is proposed.

scholarly journals Heat-Up Performance of Catalyst Carriers—A Parameter Study and Thermodynamic Analysis

Energies ◽  
2021 ◽  
Vol 14 (4) ◽  
pp. 964
Author(s):  
Thomas Steiner ◽  
Daniel Neurauter ◽  
Peer Moewius ◽  
Christoph Pfeifer ◽  
Verena Schallhart ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Transfer Coefficient ◽  
Surface Area ◽  
Internal Surface ◽  
Installation Space ◽  
Parameter Study ◽  
Thin Wall ◽  
Primary Role ◽  
Internal Surface Area

This study investigates geometric parameters of commercially available or recently published models of catalyst substrates for passenger vehicles and provides a numerical evaluation of their influence on heat-up behavior. Parameters considered to have a significant impact on the thermal economy of a monolith are: internal surface area, heat transfer coefficient, and mass of the converter, as well as its heat capacity. During simulation experiments, it could be determined that the primary role is played by the mass of the monolith and its internal surface area, while the heat transfer coefficient only has a secondary role. Furthermore, an optimization loop was implemented, whereby the internal surface area of a commonly used substrate was chosen as a reference. The lengths of the thin wall and high cell density monoliths investigated were adapted consecutively to obtain the reference internal surface area. The results obtained by this optimization process contribute to improving the heat-up performance while simultaneously reducing the valuable installation space required.

Periodically Converging-Diverging Tubes and Their Turbulent Heat Transfer, Pressure Drop, Fluid Flow, and Enhancement Characteristics

1984 ◽  
Vol 106 (1) ◽  
pp. 55-63 ◽  
Author(s):  
P. Souza Mendes ◽  
E. M. Sparrow
Keyword(s):  
Heat Transfer ◽  
Fluid Flow ◽  
Surface Area ◽  
Equal Mass ◽  
Turbulent Heat Transfer ◽  
Turbulent Heat ◽  
Transfer Coefficients ◽  
Pressure Drops ◽  
Heat Transfer Coefficients ◽  
Friction Factors

A comprehensive experimental study was performed to determine entrance region and fully developed heat transfer coefficients, pressure distributions and friction factors, and patterns of fluid flow in periodically converging and diverging tubes. The investigated tubes consisted of a succession of alternately converging and diverging conical sections (i.e., modules) placed end to end. Systematic variations were made in the Reynolds number, the taper angle of the converging and diverging modules, and the module aspect ratio. Flow visualizations were performed using the oil-lampblack technique. A performance analysis comparing periodic tubes and conventional straight tubes was made using the experimentally determined heat transfer coefficients and friction factors as input. For equal mass flow rate and equal transfer surface area, there are large enhancements of the heat transfer coefficient for periodic tubes, with accompanying large pressure drops. For equal pumping power and equal transfer surface area, enhancements in the 30–60 percent range were encountered. These findings indicate that periodic converging-diverging tubes possess favorable enhancement characteristics.

scholarly journals Experimental Investigation of Heat Transfer in Two-Pass Coolant Passages With Ribs and Film Cooling Hole Ejection

2002 ◽  
Author(s):  
D. Chanteloup ◽  
A. Bo¨lcs
Keyword(s):  
Heat Transfer ◽  
Film Cooling ◽  
Outer Wall ◽  
Reynolds Numbers ◽  
Thermochromic Liquid Crystal ◽  
Heat Transfer Characteristics ◽  
Surface Heat Transfer Coefficient ◽  
Staggered Arrangement ◽  
Cooling Hole ◽  
Surface Measurements

A study of flow in two stationary models of two-pass internal coolant passages is presented, which focuses on the heat transfer characteristics in the two-pass coolant channel. Heat transfer measurements were made with a transient technique using thermochromic liquid crystal technique to measure a surface temperature. The technique allows full surface heat transfer coefficient measurements on all the walls. The coolant passage model consisted of two square passages, each having a 20 hydraulic diameter length, separated by a rounded-tip web of 0.2 passage widths, and connected by a sharp 180 deg bend with a rectangular outer wall. Ribs were mounted on the bottom and top walls of both legs, with a staggered arrangement, and at 45 deg to the flow. The rib height and spacing were 0.1 and 1.0 passage heights, respectively. The measurements were obtained for Reynolds numbers of 25000, 50000 and 70000. One geometry is equipped with extraction holes to simulate holes for film cooling. Two series of holes are placed solely in the bottom wall, 4 holes are located in the bend, and 12 in the downstream leg. The global extraction through the holes was set to 30%, 40% and 50% of the inlet massflow. This paper presents new measurements of the heat transfer in the straight legs, and in the bend of the passage. It shows the influence of Reynolds number and extraction on full surface measurements and area averaged results.

Effect of Radial Location of Nozzles on Heat Transfer in Pre-Swirl Cooling System

2009 ◽  
Author(s):  
V. U. Kakade ◽  
G. D. Lock ◽  
M. Wilson ◽  
J. M. Owen ◽  
J. E. Mayhew
Keyword(s):  
Heat Transfer ◽  
Cooling System ◽  
Convective Heat Transfer Coefficient ◽  
Flow Visualisation ◽  
Thermochromic Liquid Crystal ◽  
Rotating Disc ◽  
Dimensional Solution ◽  
Flow Rates ◽  
Measure Surface Temperature ◽  
High Heat Transfer

This paper investigates heat transfer in a rotating disc system using pre-swirled cooling air from nozzles at high and low radius. The experiments were conducted over a range of rotational speeds, flow rates and pre-swirl ratios. Narrow-band thermochromic liquid crystal (TLC) was specifically calibrated for application to experiments on a disc rotating at ∼ 5000 rpm and subsequently used to measure surface temperature in a transient experiment. The TLC was viewed through the transparent polycarbonate disc using a digital video camera and strobe light synchronised to the disc frequency. The convective heat transfer coefficient, h, was subsequently calculated from the one-dimensional solution of Fourier’s conduction equation for a semi-infinite wall. The analysis accounted for the exponential rise in the air temperature driving the heat transfer, and for experimental uncertainties in the measured values of h. The experimental data was supported by ‘flow visualisation’ determined from CFD. Two heat transfer regimes were revealed for the low-radius pre-swirl system: a viscous regime at relatively low coolant flow rates; and an inertial regime at higher flow rates. Both regimes featured regions of high heat transfer where thin, boundary layers replaced air exiting through receiver holes at high radius on the rotating disc. The heat transfer in the high radius pre-swirl system was shown to be dominated by impingement under the flow conditions tested.

scholarly journals Numerical investigation of fluid flow and heat transfer characteristics on the aerodynamics of ventilated disc brake rotor using CFD

2014 ◽  
Vol 18 (2) ◽  
pp. 667-675 ◽  
Author(s):  
Karuppa Raj ◽  
R. Ramsai ◽  
J. Mathew ◽  
G. Soniya
Keyword(s):  
Heat Transfer ◽  
Numerical Analysis ◽  
Heat Dissipation ◽  
Rotational Symmetry ◽  
Temperature Drop ◽  
Brake Disc ◽  
Heat Transfer Characteristics ◽  
Transfer Characteristics ◽  
Ansys Cfx ◽  
Brake Rotor

Ventilated brake discs are used in high speed vehicles. The brake disc is an important component in the braking system which is expected to withstand and dissipate the heat generated during the braking event. In the present work, an attempt is made to study the effect of vane-shape on the flow-field and heat transfer characteristics for different configurations of vanes and at different speeds numerically. Three types of rotor configurations circular pillared, modified taper radial and diamond pillar vanes were considered for the numerical analysis. A rotor segment of 20? was considered for the numerical analysis due to its rotational symmetry. The pre processing is carried out with the help of ICEM-CFD and analysis is carried out using ANSYS CFX 12.1. The three dimensional flow through the brake rotor vanes has been simulated by solving the appropriate governing equations viz. conservation of mass, momentum and energy using the commercial CFD tool, ANSYS CFX 12. The predicted results have been validated with the results available in the literature. Circular pillar rotor vanes are found to have more uniform pressure and velocity distribution which results in more uniform temperature drop around the vanes. The effect of number and diameter of vanes in the circular pillared rotor is studied and the geometry is optimized for better mass flow and heat dissipation characteristics.

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