This SAE Information Report has been prepared at the request of the SAE Road Vehicle Aerodynamics Forum Committee (RVAC), incorporating material from earlier revisions of the document first prepared by the Standards Committee on Cooling Flow Measurement (CFM).
Although a great deal is already known about engine cooling, recent concern with fuel conservation has resulted in generally smaller air intakes whose shape and location are dictated primarily by low vehicle drag/high forward speed requirements. The new vehicle intake configurations make it more difficult to achieve adequate cooling under all conditions. They cause cooling flow velocity profiles to become distorted and underhood temperatures to be excessively high. Such problems make it necessary to achieve much better accuracy in measuring cooling flows.
As the following descriptions show, each company or institution concerned with this problem has invested a lot of time and as a result gained considerable experience in developing measuring techniques that appear to achieve reliable results. There is, however, little uniformity at the present time among the methods used by different companies and no indication at this time of a trend towards a simple and universally acceptable measuring technique.
The contents of this document are judged by the Road Vehicle Aerodynamics Forum Committee to be of value in outlining current and historical techniques for cooling air flow measurements. Common practice for cooling flow assessment has developed significantly since the original issue of this document and this revision brings the document up to date with current approaches; including in particular a new section on the use of Computational Fluid Dynamics (CFD) for cooling air flow assessment.