DEVELOPMENT OF A HOT-WIRE MEASUREMENT TECHNIQUE FOR MODERATE INTENSITY THREE-DIMENSIONAL FLOWS

This study is concerned with the development of a new data reduction method based on the use of a hot wire anemometer operated at constant temperature for the determination of mean velocity and Reynolds stress components in three-dimensional turbulent flows. In addition, an experimental study which includes measurements in the near field of an axisymmetric jet is performed to demonstrate the method's applicability in flow of moderate intensity levels.; The technique is based on the use of a stationary normal wire and a single rotatable slant wire used to determine the local mean velocity vector and all six components of the Reynolds stress tensor in moderately skewed flows where low to moderate turbulence intensity prevail. The method utilizes normal and slant wire data obtained relative to optimum planes which define locations where the wire is either insensitive to a certain transverse fluctuation or is equally sensitive to both transverse fluctuation components. The method is of general applicability such that hot wire signals processed with or without a linearizer may be utilized. Two different hot wire response models leading to the calculation of mean and turbulence quantities are developed.; In order to examine the validity of the method in low intensity flows (u/U {dollar}le{dollar} 10%), turbulent pipe flow data taken under simulated skewed flow conditions were analyzed. Presentation and discussion of these results are given in Chapter III. Data obtained with and without a linearizer in the near field of an axisymmetric free jet issuing from fully-developed turbulent pipe flow were also analyzed in order to examine the validity of the method when applied to moderate intensity flows when the local mean flow is arbitrarily skewed in pitch and yaw. The accuracy of the method is enhanced when a flow-angle dependent model for the yaw sensitivity factor is employed in the data reduction process.