Automotive cooling system component interactions

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Title: Automotive cooling system component interactions
Author: Walter, John D
Abstract: In the development of automotive cooling systems , cooling airflow rate predictions are generally based on cooling system component flow resistance characteristics obtained from tests of individual or "isolated" components . The assumption is that the flow resistance of a complete cooling package is equivalent to the sum of the flow resistance of the isolated components . It is shown in the current investigation that this assumption can lead to significant errors in calculations of the net flow resistance of the cooling package . Furthermore , it is demonstrated that the interaction between the fan and the surrounding components is the primary source of this discrepancy . Understanding how the fan interacts with the other cooling package components is the key to understanding component interactions . Fan pressure jump evaluations based on thrust measurements taken while the fan is operating downstream of a heat exchanger (s ) and upstream of the engine bay are shown to provide accurate installed fan performance evaluations . It is found that restriction of the swirl component upstream of the fan by a low resistance flow straightening device does not significantly affect fan performance . However , as the free flow area of the heat exchanger decreases (i .e . , as the blockage increases ) , the fan performance is modified . The engine bay , a downstream obstruction in the direct path of the fan efflux , does not significantly affect fan performance . An isolated heat exchanger mounted on a flowstand experiences an approximately uniform approach flow . In contrast , when mounted in a cooling package , the energy input from the fan and blockage at the comers of the fan shroud induces a less uniform flow which must always lead to higher heat exchanger pressure drops . Utilizing the fan thrust and plenum pressure measurements , the "installed" (i .e . , mounted as part of the cooling package ) heat exchanger pressure drop is readily evaluated and the results support the conclusion that interference effects lead to a higher heat exchanger pressure drop .
URI: http : / /hdl .handle .net /2346 /14361
Date: 2001-05

Citation

Automotive cooling system component interactions. Doctoral dissertation, Texas Tech University. Available electronically from http : / /hdl .handle .net /2346 /14361 .

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