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The use of climatic wind tunnels is a well-established technique for reducing product development cycle times. Given the wide range of climatic conditions that are demanded, energy costs can be a significant component of a test run. The paper describes a research project which involved the development and calibration of a detailed model of the operation of a climatic wind tunnel (CWT) and its use in evaluating alternative plant supervisory control strategies, together with possible modifications of plant configuration.

The application of high performance engines and climate control systems, coupled with constraints relating to vehicle styling, aerodynamics and underbonnet packaging, continues to present demanding thermal management challenges in the design and layout of the front-end cooling module. Several computational fluid dynamics techniques are now available to assist in this design and packaging process, but many of these require a high level of specialization from the user. The work reported here outlines a relatively simple 1-dimensional technique to aid in the analysis and optimization of the cooling pack configuration. The tool can be used interactively by a multi-skilled vehicle engineer throughout the entire design and development of a new vehicle.

A survey and analysis of the body sealing and interior airflow performance of a range of medium-sized passenger cars has been conducted. These studies have been carried out under static and dynamic exterior airflow conditions in a full scale wind tunnel, at airspeeds of up to 96km/h, and the ventilation performance of the vehicles characterized in terms of body leakage and extract airflow, equivalent hole size, total interior airflow and blower power requirements. In addition, more fundamental laboratory studies of the effect of interior airflow path and extract geometry have been conducted, leading to an enhanced understanding of the results obtained from the full-vehicle work.

Due to customer demand, the features list of motor vehicles for the next century will require manufacturers to design vehicles that not only keep up with exacting legislation changes, but also meet higher specifications combined with reduced product cycle times. This paper outlines the development of MIRA's Climatic Wind Tunnel (CWT) as a commercially sponsored venture with total funding being generated within the Automobile Industry, and the effect that this sponsorship had on the fundamental design parameters. The facility can provide air temperatures from -40°C to +55°C, and humidity from 5% to 95% with wind and road speeds up to 200km/h. Both solar and hot road radiation can be simulated. It can accommodate both 2-wheel and 4-wheel drive vehicles and can absorb up to 300 kW of power at the road wheels. The construction of the £4.5 million CWT project was project managed by MIRA's own Civils and Facility Departments and took 14 months to complete from start to finish.