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Global environmental issues require that new alternatives to R-134a refrigerant be investigated by the automotive air-conditioning (A/C) industry. Test facilities must be able to handle the challenges that these refrigerants pose. One refrigerant currently under investigation is Carbon Dioxide (CO2). The high pressure and toxicity of CO2, require the test facility to institute more stringent guidelines and add equipment to safeguard personnel. The operating characteristics of this refrigerant, and the additional equipment needed for the test A/C system, necessitate more complex automated test data acquisition and control. The addition of an internal heat exchanger in the CO2 A/C system is an example of the changes required. Different thermal characteristics introduced by this refrigerants mean that new measurement devices such as higher-pressure transducers are required. Compatibility between test stand sealing materials, hose assemblies, etc., and the refrigerant must be addressed.

Aerodynamic measurements in automotive wind tunnels are degraded by test section interference effects, which increase with increasing vehicle blockage ratio. The current popularity of large vehicles (i.e. trucks and sport utility vehicles) makes this a significant issue. This paper describes the results of an experimental investigation carried out in support of the Ford/Sverdrup Driveability Test Facility (DTF), which includes an aero-acoustic wind tunnel (Wind Tunnel No. 8). The objective was to quantify the aerodynamic interference associated with two candidate test section configurations for Wind Tunnel No. 8-semi-open jet and slotted wall. The experiments were carried out at 1/11-scale in Sverdrup laboratories. Four automobile shapes (MIRA models) and six Sport Utility Vehicle (SUV) shapes representing blockages from 7% to 25% were used to evaluate changes in measured aerodynamic coefficients for the two test section configurations.

Pressure-sensitive paint (PSP) technology is a technique used to experimentally determine surface pressures on models during wind tunnel tests. The key to this technique is a specially formulated pressure-sensitive paint that responds to, and can be correlated with the local air pressure. Wind tunnel models coated with pressure-sensitive paint are able to yield quantitative pressure data on an entire model surface in the form of light intensity values in recorded images. Quantitative results in terms of pressure coefficients (Cp) are obtained by correlating PSP data with conventional pressure tap data. Only a small number of surface taps are needed to be able to obtain quantitative pressure data with the PSP method. This technique is gaining acceptance so that future automotive wind tunnel tests can be done at reduced cost by eliminating most of the expensive pressure taps from wind tunnel models.