Low Reynolds number supersonic nozzles have been studied for several years due to their significance in applications in micro-spacecraft. As satellite design reduces in mass and size, smaller more versatile propulsion systems will be required. In response to the need, a conical nozzle (expansion ratio of 25 and 20° half-angle of divergence) with throat dimensions of 600µm x 300µm has been designed and fabricated with capabilities in thrust magnitude control. The device utilizes the expansion of a silicone membrane, located on the upper surface of the supersonic micro-nozzle throat, as a mechanism to reduce the throat cross sectional area, and consequently vary the nozzle's expansion ratio. The flow through the nozzle, with and without flow control, has been modeled using an analytical one-dimensional isentropic model and a viscous three-dimensional computational fluid dynamics (CFD) model using FLUENT. The ability of the proposed flow control device to affect the flow rate, nozzle efficiency, and thrust output has been determined using CFD. The micro-nozzle has been tested under separation conditions; under these conditions the nozzle performance has been experimentally determined. Furthermore, successful flow control has been demonstrated. Possible future developments for this flow control concept are discussed, which primarily include improvements in fabrication and experimentation techniques.

Library of Congress Subject Headings

Nozzles--Fluid dynamics; Microspacecraft; Space vehicles--Equipment and supplies

Publication Date


Document Type


Student Type


Degree Name

Mechanical Engineering (MS)

Department, Program, or Center

Mechanical Engineering (KGCOE)


Jeffrey Kozak

Advisor/Committee Member

Mark Kempski

Advisor/Committee Member

Kevin Kochersberger


RIT – Main Campus

Plan Codes