Question

what are the Sources and calculations of expected errors, uncertainties and delays of wind tunnel test for a vehicle ?

Answer 1

WIND TUNNEL TEST

We don’t know how to calculate theoretical behavior of vehicles under real life aerodynamic environments. Wind tunnel testing solves that problem. Wind tunnel is a kind of large diameter tube where the flow of air starts in real life scenarios and a model is kept in the tunnel to understand it’s behaviour, forces and equilibrium conditions.Important thing is that the object is kept stationary.

Wind tunnels were used for aeroplanes; later high speed vehicles also started being tested and it changed a lot about their looks and fuel efficiency.

CAUSES OF ERRORS/UNCERTAINTIES/DELAYS

1. Unable to create actual testing environment where road moves relative to vehicles while in wind tunnel testing they are kept stationary
2. It's a complex method which requires extreme precision regarding scale and Re Number.
3. Temperature and pressure variation
4. Unable to all measure forces
5. Air quality inside wind tunnel testing will never match actual air outside such as it’s humidity, density or temperature which varies at very short distance in some countries.
6. Setup is costly; any compromise will lead to poor testing results.
7. Leakage and calculation of angle of attack,drag and lift values.
8. Noisy