Search Results

This paper outlines the creation of a facility for simulating on-road transients in a model scale, ¾ open jet, wind tunnel. Aerodynamic transients experienced on-road can be important in relation to a number of attributes including vehicle handling and aeroacoustics. The objective is to develop vehicles which are robust to the range of conditions that they will experience. In general it is cross wind transients that are of greatest significance for road vehicles. On-road transients include a range of length scales but the most important scales are in the in the 2-20 vehicle length range where there are significant levels of unsteadiness experienced, the admittance is likely to be high, and the reduced frequencies are in a band where a dynamic test is required to correctly determine vehicle response.

The effect of the upstream wake of a Formula 1 car on a following vehicle has been investigated using experimental and computational methods. Multiple vehicle studies in conventional length wind tunnels pose challenges in achieving a realistic vehicle separation and the use of a short axial length wake generator provides an advantage here. Aerodynamic downforce and drag were seen to reduce, with greater force reductions experienced at shorter axial spacings. With lateral offsets, downforce recovers at a greater rate than drag, returning to the level for a vehicle in isolation for offsets greater than half a car width. The effect of the wake was investigated in CFD using multiple vehicle simulations and non-uniform inlet boundary conditions to recreate the wake. Results closely matched those for a full two-vehicle simulation provided the inlet condition included unsteady components of the onset wake.

It is well documented that the aerodynamic performance of an open wheel race car is degraded when closely following another car. The greatest performance loss is usually experienced by the front-mounted wing leading to reduced aerodynamic downforce, handling imbalance and a reduced overtaking capability. Although previous wind tunnel studies have been performed to investigate this race situation the model scales have generally been compromised in order to achieve representative separation between the two test vehicles within the confines of the wind tunnel working section and particularly within the limited length of the moving ground plane. This study addresses that issue by using a very short, bluff body to create an accurate representation of the wake flow from the leading car in order to provide additional, effective test length ahead of the instrumented model.