Micro nozzles sonic diamond.

Author(s)

Suelene Silva Mammana

• Document type: Doctoral Thesis
• Press: São Paulo.
• Institution: Universidade de São Paulo (USP). Instituto de Física (IF/SBI)
• Defense date: 2002-06-06

Examining board members

Maria Cecilia Barbosa da Silveira Salvadori; Ibere Luiz Caldas; Fernando Lázaro Freire Junior; Homero Santiago Maciel; Marcos de Mattos Pimenta

• Advisor: Maria Cecilia Barbosa da Silveira Salvadori; Mauro Sergio Dorsa Cattani

Abstract

In this work an original method for the fabrication of diamond micronozzles with converget-divergent profile is presented. The method uses the deposition of polycrystalline diamond over a mold, which is subsequently removed. The referred molds are tungsten wires patterned by means of an electrolytic etching procedure in a way that the divergent-convergent profile is generated. The main motivation for producing such micronozzles is its application as passive flow controllers and flow meters elements when operating under critical flow conditions. The micronozzles produced here were tested in order to determine the critical flow parameters that are necessary for its operation, as passive flow controllers and flow meters elements. The critical flow parameters (critical mass flow rate, critical pressure ratio and critical volumetric flow rate), the Reynolds number range and the discharge coefficient were determined for all the microdevices produced. The Reynolds number for the microdevices was found to be in the range of 1x10 POT.3-7x10 POT.4. For instance, the diamond micronozzle with smaller throat diameter, (16+/-1)x10mum, presented critical mass flow rate of (0,344+0,006)g/min, critical volumetric flow rate of (314+/-5)cm POT.3/min and discharge coefficient of (1,27+/-0,19). Therefore, diamond micronozzles were successfully fabricated with convergent-divergent profile and the critical flow parameters necessary for its operation, as passive flow controllers and flow meters elements, were determined. (AU)