The braking system on a wide body aircraft absorbs approximately 43 MJ per brake during landing. In order to meet future noise requirements, there is design pressure to modify the fan that may include lowering the fan speed and associated flow rate through the braking system. This initial study evaluates the impact of reducing the fan flow rate on the amount of heat removed from the brake. The addition of 43 MJ will increase the brake temperature to 549 °C, which must be reduced to 400 °C. The time required to cool the brakes to 400 °C is the minimum turnaround time. Computational fluid dynamics (CFD) is used to numerically calculate the heat transfer and fluid flow through the wheel and brake system. The CFD model is a 2-D axisymmetric conjugate heat transfer calculation that includes the brake as a solid component. Transient calculations were made for cooling fan at volumetric flow rates between 250 and 50 Liters/s. The time to cool varied from a minimum of 12.8 minutes at 250 L/s to a maximum of 35.3 minutes for 50 L/s. The trend of cooling time versus flow rate CFD results compared well with data available from in service aircraft. Although the geometry is greatly simplified, this initial model has given some insight into the impact of reducing fan flow rates on cooling time. Since there are such high temperatures, there will be radiation heat transfer losses, and the inclusion of this will improve the accuracy of the cooling time predictions. The flow path has been simplified to accommodate the 2-D axisymmetric assumption, and a 3-D calculation with higher fidelity geometry would improve the calculations. In addition, the other solid components of the brake system could be added for an increased accuracy in cooling time prediction. The brake thermal conductivity was assumed to be isotropic, but it may be dependent on direction. Also, there will be contact resistance between the brake disks, which will change the temperature distribution and heat transfer.


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    Titel :

    Active cooling of aircraft brakes


    Beteiligte:


    Erscheinungsdatum :

    2011


    Format / Umfang :

    12 Seiten, 9 Bilder, 3 Tabellen, 6 Quellen


    Anmerkungen:

    (nicht paginiert)


    Medientyp :

    Aufsatz (Konferenz)


    Format :

    Datenträger


    Sprache :

    Englisch




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