A study of the development of steady and periodic unsteady turbulent wakes through curved channels at positive, zero, and negative streamwise pressure gradients /
| Main Author: | |
|---|---|
| Other Authors: | , , |
| Format: | Thesis Book |
| Language: | English |
| Published: |
1993.
|
| Subjects: | |
| Online Access: | ProQuest, Abstract Link to OAKTrust copy |
| Abstract: | The development of turbomachinery wake flows are largely influenced by streamline curvature and streamwise pressure gradient. The objective of the investigation reported in this dissertation is to study the development of the wake under the influence of streamline curvature and streamwise pressure gradient. The experimental investigation is earned out in two phases. The first phase involved the study of the wake behind a stationary circular cylinder (steady wake) in curved channels at positive, zero, and negative streamwise pressure gradients. The mean velocity and Reynolds stress components are measured using a X-hot-film probe. The measured quantities obtained in probe coordinates are transformed to a curvilinear coordinate system along the wake centerline and are presented in similarity coordinates. The results of the steady wakes indicate strong asymmetry in velocity and Reynolds stress components. However, the velocity defect profiles in similarity coordinates are almost symmetrical and follows the same distribution as the zero pressure gradient straight wake. The results of Reynolds stress distributions indicate higher values on the inner side of the wake than the outer side. Other quantities, including the decay of maximum velocity defect, growth of wake width, and wake integral parameters, are also presented for the three different pressure gradient cases of steady wake. The decay rate of velocity defect is fastest for the negative streamwise pressure gradient case and slowest for the positive pressure gradient case. Conversely, the growth of the wake width is fastest for the positive streamwise pressure gradient case and slowest for the negative streamwise pressure gradient. In the second phase, the development of periodic unsteady wakes, generated by the circular cylinders of the rotating wake generator, in a curved channel at zero streamwise pressure gradient is studied. Instantaneous velocity components of the periodic unsteady wakes, measured using a stationary X-hot-film probe, are analyzed by employing phase-averaging techniques. The temporal distribution of velocity and Reynolds stress components obtained in a stationary frame of reference are transformed to a spatial distribution in a relative frame of reference... |
|---|---|
| Item Description: | Vita. "Major subject: Mechanical Engineering." |
| Physical Description: | xxiii, 252 leaves : illustrations ; 28 cm |
| Bibliography: | Includes bibliographical references. |