Cooling Inlet Aerodynamic Performance and System Resistance

Jack Williams; Dinakara Karanth; Walt Oler

doi:10.4271/2002-01-0256

2002-03-04

Cooling Inlet Aerodynamic Performance and System Resistance 2002-01-0256

This report is a contribution to the understanding of inlet aerodynamics and cooling system resistance. A characterization of the performance capability of a vehicle front-end and underhood, called the ram curve, is introduced. It represents the pressure recovery/loss of the front-end subsystem - the inlet openings, underhood, and underbody. The mathematical representation, derived from several experimental investigations on vehicles and components, has four basic terms:

Inlet ram pressure recovery; free-stream energy recovered when the vehicle is moving
Basic inlet loss; inlet restriction when the vehicle is stationary
Pressure loss of the engine bay
Engine bay-exit pressure

Not surprisingly, the amount of frontal projection of radiator area through the grille, bumper and front-end structure (called projected inlet area), and flow uniformity play a major role in estimating inlet aerodynamic performance. One experimental investigation demonstrated that the ram curve is independent (essentially) of the fan/shroud system installed in the vehicle. Another experiment showed that the engine-bay pressure loss (which includes the interference of the underhood package on fan performance) might be small compared to the other resistances. The universal characteristic map of fan and system performance can be used to track airflow changes during early vehicle design tradeoff studies.

SAE MOBILUS

Subscribers can view annotate, and download all of SAE's content. Learn More »

Access SAE MOBILUS »

Digital $37.00 Print $37.00

Preview Document

We also recommend:

Standards

SAE Mobilus®

Publications

News

Events

Professional Development

A World in Motion (PreK-12)

Participate with SAE

SAE Membership

Donate

Cooling Inlet Aerodynamic Performance and System Resistance 2002-01-0256

SAE MOBILUS