1. UTAC/ICE_Lab C. Vallaude, Brussels, 14-15/11/12
WLTP-DTP-LabProcICE-166
RLD Methods Comparison Study carried out in 2000 for the ISO/TC22/SC5/WG10
UTAC/ICE_Lab
C. Vallaude, Brussels, 14-15/11/12

2. Study Presentation (1/2)
Study: done in 2000 for the ISO group
=> Was presented to the group in June 2001
Objective : compare different RLD methods and calculations
Objective today: extract the data corresponding to tests complying with the GTR methods

3. Study Presentation (2/2)
Test Vehicles
=> Obj : cover the extreme situations
1 Small M1
1 N1
Tests methods
Wind tunnel + Ch. Dynamometer => Alternative Method
Road => ISO10521 (same method as annex 4, § of draft GTR)

4. Test Vehicles Item Vehicle 1 Vehicle 2 Type M1 N1 Mass UM 900kg 1500kgLM
1100kg
1700kg
Front/rear
60/40%
59/41%
Tyre
Dimensions
175/60R14
195/70R14
Pressure
2.2 Bar
3.0 Bar
Lengh
3.7m
4.4m
Width
1.6m
1.8m
Height
1.4m
1.9m
Frontal area
1.813m²
3.040m²

5. Alternative method (Tunnel +Ch/Dy)
Test methods (1/2)
Alternative method (Tunnel +Ch/Dy)
Scx measured in 2 wind tunnels
Frictions measured on 2 chassis dynamometers
Measurements of rolling resistance loads made up to 120 km/h
Warm up of axles : 30min at 120km/h for rear, 20min at 120km/h for front
Ch/Dy1
Ch/Dy2
Smooth steel
Single roller
Ø=1.273m (50”)
Ø=1.750m (69”)

6. Test methods (2/2) Road method 1 road Almost zero slope Length: ~2 km
=> thus 2-part CD (120-80km/h & 80-20km/h)
Generally warm, quite sunny conditions ( ~20 °C)
Low speed winds from 0 to 3 m/s

7. Wind Tunnel Results V1 V2 WT1 0.649 1.112 WT2 0.670 1.150 Mean 0.660
1.131
Diff
3.2%
-3.4%

8. Repeatability (1/2) Road testing
Maximum difference from 1% to 4.4% between two tests

9. Repeatability (2/) WT + ChDy testing
Maximum difference from 2% to 4% (including 2 wind tunnels and 2 ChDy)

10. WT + Ch/Dy & Road LW (1/2)
Road data are averaged over 4 tests for both vehicles
Opposite trends with the 2 vehicles

11. Conclusion Max difference for road testing around 4% at low wind
Max difference for WT + ChDy around 4%
deviations for both methods
Comparison WT+ChDy & Road
For V1 -2.4% to -4.7%
For V2 +2.1% to +2.9%
depends on vehicle
Conclusion in 2001, equivalency of both methods