Air jet cooling of brake discs

Abstract

This paper reports on an investigation of a novel approach to the cooling of brake discs, based on the application of impinging air jets. This has the capacity to enhance the heat transfer coefficients at the disc surface quite considerably without affecting the disc design, so that the disc construction may then be optimized without reference to heat transfer. Using a purpose built test-rig, disc temperature histories were recorded using IR thermography for varying jet air flow rates, angle of impingement, dimensionless distance from the brake disc and rotational speed. As well as comparing cooling effectiveness for different test parameters, convective heat transfer coefficients were calculated from the transient temperature data and were used as boundary conditions for a finite element model of the process. The results obtained from this investigation suggest that the higher convection coefficients achieved with jet cooling will not only reduce the maximum temperature in the braking cycle but will reduce thermal gradients, since heat will be removed faster from hotter parts of the disc. Jet cooling should therefore be effective to reduce the risk of hot spot formation and associated disc distortion.

Capability Assessment of Five Different RANS-Based Turbulence Models to Simulate the Various Regions of Slot Turbulent Impingement Jet Flow

“…Many applications have been mentioned for this phenomenon in the literature. For example it is possible to mention metal industry, cooling of electronic components, defogging by heating optical surfaces, cooling turbine components and cooling sensitive parts in machining [1][2][3]. In this study, the impinging jet flow is divided into four regions.…”

Three-element model of frictional heating during braking with contact thermal resistance and time-dependent pressure

“…The obtained results can be applied to finding the transient stress fields of the brake under an emergency braking [35], to theoretical study of hot spots in disc brakes [36], to the cooling of brake discs [37], etc.…”

Infrared thermography with non-uniform heat flux boundary conditions on the rotor endwall of an axial turbine

“…In the field of thermo-fluid-dynamics, infrared thermography is used to measure convective heat transfer both at a fundamental level (Scherer et al [3]) and in more applicationoriented contexts (Schulz [4]). Application of the technique to rotating machinery or components is of interest for a variety of fields (fundamental fluid mechanics, Cardone et al [5]; automotive, Lyons et al [6]; railway engineering, Siroux et al [7]), but limitations in the acquisition speed of the detector typically allow quantitative measurements only in a circumferentially averaged fashion. An attempt to reconstruct a full temperature map of a rapidly rotating disk is reported in 2002 by Astarita et al [8].…”