COBEM99

S8 Engenharia Aeroespacial

Title:

A NUMERICAL STUDY OF TWO-PHASE FLOWS IN AXISYMMETRIC SOLID ROCKET MOTOR NOZZLES

Summary :

ALUMINUM OXIDE PARTICLES PRESENT IN THE FLOW IN SOLID ROCKET MOTOR NOZZLES CONTRIBUTE TO THE LOSS OF THRUST AS MOMENTUM IS TRANSFERED FROM THE GAS PHASE TO THE PARTICLES. A TOOL CAPABLE OF SIMULATING SUCH FLOWS HAS BEEN DEVELOPED SO AS TO PREDICT THE THRUST LOSS AND THE BEHAVIOR OF THE ALUMINA PARTICLES INSIDE THE FLOW. THE PROBLEM FOR THE GAS PHASE IS MODELED BY THE EULER EQUATIONS AUGMENTED WITH SOURCE TERMS TO TAKE THE INTERACTION BETWEEN PHASES INTO ACCOUNT. THE PARTICLES ARE SIMULATED AS A CONTINUUM OF PARTICLES, AND THE FORMULATION IS AGAIN VERY SIMILAR TO THE EULER EQUATIONS EXCEPT THAT THERE IS NO COUNTERPART TO THE PRESSURE. THE GOVERNING EQUATIONS ARE INTEGRATED IN TIME BY THE IMPLICIT EULER METHOD IN THE CONTEXT OF THE BEAM AND WARMING APPROXIMATE FACTORIZATION SCHEME. SINCE THE SCHEME USES CENTRAL DIFFERENCES, ARTIFICIAL DISSIPATION TERMS MUST BE ADDED AND PULLIAM S NONLINEAR ARTIFICIAL DISSIPATION MODEL WAS SELECTED. THE USE OF THE NONLINEAR ARTIFICIAL DISSIPATION TERMS HAS YIELDED A MUCH FASTER CONVERGENCE RATE THAN SIMPLER ARTIFICIAL DISSIPATION MODELS. A DETAILED PARAMETRIC STUDY WAS PERFORMED IN ORDER TO PRECISELY DETERMINE HOW THE SOLUTION QUALITY AND THE CONVERGENCE RATE ARE AFFECTED BY THE CHANGES IN THE PROBLEM VARIABLES. KEYWORDS: TWO-PHASE FLOWS, AXISYMMETRIC FLOWS, NOZZLE, NONLINEAR ARTIFICIAL DISSIPATION, EULER EQUATIONS

Author :

Azevedo, João L. F.
da Silva, Rubens Peixoto
Menezes, Shailon Ian Abdala
Novo, Marcos Augusto

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