PANG Jiabin. Analysis and correction of aerodynamic drag measurement errors in a 3/4-open jet automotive wind tunnel[J]. 2024, 42(7): 112-117.DOI: 10.7638/kqdlxxb-2024.0026.
Analysis and correction of aerodynamic drag measurement errors in a 3/4-open jet automotive wind tunnel
Automotive wind tunnels are essential in replicating the real-road aerodynamicenvironment for vehicle testing. However
the confined dimensions of the 3/4-open test section
along withthe ground boundary layer and jet shear layers
introduce disturbances to the airflow
leadingto errors in aerodynamic drag measurements. Utilizing a simplified potential flow model
thisstudy identifies and quantifies four critical systematic errors within the test section: solidblockage
nozzle blockage
collector blockage
and horizontal pressure gradient. The solidblockage tends to underestimate t
he measured aerodynamic drag
while the nozzle andcollector blockages result in overestimations. The interplay of these effects creates a selfcorrecting mechanism that enables the testing of larger vehicle models within the wind tunnel. Employing the Mercker-Wiedemann correction method at Tongji University's full-scale aeroacoustic wind tunnel
this research conducted a correction analysis on three vehicles of varying sizes. The findings indicate that
with a criterion of keeping the aerodynamic drag coefficient error within 1%
the wind tunnel is capable of accommodating vehicles with ablockage ratio of up to 15%. Moreover
the horizontal pressure gradient is identified as asignificant source of error in the drag coefficient measurement. These insights underscore thenecessity for stringent design and acceptance protocols in wind tunnel engineering with d
C
p
(
x
)/d
x
0.001/m to ensure measurement precision.
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references
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