Flow field in a hot air jet impingement oven - Part II: Multiple impingement jets

The axial velocity component of three and four jet arrays impinging on a fl at plate have been measured using a laser Doppler anemometer. The axial vel ocity profiles for all jets were found to demonstrate characteristics of a turbulent jet in its potential core region. Between neighboring jets, rever sal of the airflow occurred. At measurements closer to the flat plate, the reverse flow velocity values were found to be about 50% of the maximum jet velocity. The results indicated that the products passing under multiple je ts may experience uneven heating rates, depending upon the product size and jet orifice spacing.