Basic Studies in Flueric Demodulation,
Abstract
During an experimental study of flueric demodulation, it was noticed that a small degree of demodulation naturally occurs in the highly nonlinear flow associated with the growth of small disturbances in a laminar jet. It was discovered that a pronounced degree of demodulation could be obtained by including boundaries in the jet flow field. These forms of flueric demodulation are herein referred to as free shear flow and induced boundary layer demodulation respectively, and this report is concerned with the substantiation and explanation of these flow phenomena. The report also includes selected data describing the gain and bandwidth characteristics of an unbounded round laminar jet and data describing demodulation characteristics when a conical boundary is inserted on axis of a round jet. The entire study has been made with a one-half inch diameter water jet which is operated at a Reynolds number of 900, and is disturbed upstream of the nozzle by sinusoidal velocity perturbations at frequencies on the order of 3Hz. (It is believed that an air device operating in the KHz range could be designed using the Reynolds and Strouhal numbers as scaling parameters.) It has been observed that the disturbed shear flow augments the mean velocity of the bounding flow of the jet. It is presumed that the pseudo ring vortices induce a vortext boundary layer flow which has the observed effect of retarding the mean flow in the vicinity of the boundary. (Author)
Document Details
- Document Type
- Technical Report
- Publication Date
- Oct 01, 1968
- Accession Number
- AD0722390
Entities
People
- H. H. Unfried