Transient thermal response of a highly porous ventilated brake disc

Abstract

The transient thermal response of a newly developed ventilated brake disc cored with a porous medium (wire-woven bulk diamond) is compared with those of a solid brake disc and a conventionally ventilated brake disc with pin fins. The best-performing brake disc vis-à-vis the operating temperature is dependent on the duration of braking: for a short braking event, T(solid) \ T(pin-finned) \ T(porous); however, for extended braking T(porous) \ T(pin-finned) \ T(solid). These experimental results are explained in terms of the governing thermophysical parameters using a classical firstorder unsteady-state differential equation. The initial rate of increase in the brake disc temperature is dominated by the thermal capacity term; hence, for a short braking event, solid discs with a large thermal capacity operate at a low temperature. However, for extended braking, ventilated discs run cooler and reach lower steady-state temperatures than solid rotors do owing to the increased convective surface area and the forced convection in the ventilated channels. With the wire-woven bulk diamond core which allows a slightly lighter disc than the conventional pin-finned disc, a substantially lower steady-state temperature can be achieved, resulting from promoted flow mixing by three-dimensional wire-woven bulk diamond ligaments which enhance convection.

Wire-woven cellular metals: The present and future

“…Recently, a new class of ventilated brake disc with a core of wire-woven metal, WBD has been introduced [108,109]. A single-layered WBD was first assembled using helically formed steel wires (SAE1006B) with the diameter of 1.5 mm and the pitch of 19mm.…”

Ağir Hizmet Araci Fren Diski Soğuma Davranişinin İncelenmesi

“…Bu nedenle, fren disklerinde ısı transferinin iyileştirilmesi için havalandırma kanatçıklarının optimizasyonu aktif bir araştırma alanı olmaktadır. Literatürde yer alan çalışmaların büyük çoğunluğunu binek ve yüksek performans taşıtı havalandırmalı fren diskleri üzerine gerçekleştirilen sayısal ve deneysel çalışmalar oluşturmaktadır [1], [3]- [17]. Ayrıca literatürde hızlı trenlerde kullanılan havalandırmalı fren disklerinin soğuma başarımlarının incelendiği çalışmalara rastlanmaktadır [18], [19].…”

“…Bu sayede dolu fren disklerine göre daha etkin ısı transferi karakteristiği sergilemektedirler. Havalandırmalı fren diskleri binek, hafif ticari ve birçok ağır hizmet aracında geniş bir uygulama alanına sahiptir [1].…”

The Structural Design of a High-Performance WBD Brake Disc

“…The highly porous cellular wire-woven bulk diamond (WBD) has been shown to be an excellent medium for the ventilated core of a brake disc [10][11][12][13] to improve the heat dissipation characteristics of a brake disc as the convective cooling is enhanced. Laboratory tests [10,12] showed the prototype WBD disc to operate at a 15-25% lower steady state temperature as compared to the commercially available pin-finned disc or solid brake disc. The results were confirmed with onthe-vehicle tests [13].…”

“…Mew et al [10] selected the WBD material as the highly porous medium in the ventilated channel of the brake disc because of its superior strength over other types of cellular structures. The yielding mechanism of the WBD material is complicated and highly dependent on the wire diameter and slenderness ratio of the struts.…”