Active skin for turbulent drag reduction

Due to the character of the original source materials and the nature of batch digitization, quality control issues may be present in this document. Please report any quality issues you encounter to digital@library.tamu.edu, referencing the URI of the item.Includes bibliographical references (leaves 107-111).Issued also on microfiche from Lange Micrographics.Drag reduction for aerial vehicles has a range of positive ramifications: reduced fuel consumption with the associated economic and environmental consequences, larger flight range and endurance and higher achievable flight speeds. This work capitalizes on recent advances in active turbulent drag reduction and active material based actuation to develop an active or "smart" skin for turbulent drag reduction in realistic flight conditions. The skin operation principle is based on computational evidence that spanwise traveling waves of the right amplitude, wavelength and frequency can result in significant turbulent drag reduction. Such traveling waves can be induced in the smart skin via active-material actuation. The flow control technique pursued is "micro" in the sense that only micro-scale wave amplitudes (order of 30[]m) and energy inputs are sufficient to produce significant benefits. Two actuation principles are proposed and analyzed and different skin designs based on these two actuation principles are discussed. The feasibility of the different actuation possibilities (such as Shape Memory Alloys and Piezoelectric material based actuators) and relative merits of different skin designs are discussed. Multi-step dynamic analyses are performed to study the response of the skin at various actuation frequencies