ADVANCED CFD METHODOLOGY FOR FAST FLOW TRANSIENTS ENCOUNTERED IN NON-LINEAR COMBUSTION INSTABILITY PROBLEMS

THE ROCKET THRUST CHAMBERS OFTEN EXPERIENCE COMBUSTION INSTABILITIES WHICH MAY RESULT IN REDUCED PERFORMANCE, INCREASED STRUCTURAL LOADS AND ULTIMATELY IN CATASTROPHIC ENGINE FAILURE. EXISTING ANALYTICAL METHODS ARE GENERALLY LIMITED TO LINEAR-COMBUSTION INSTABILITIES. RELATIVELY LITTLE HAS BEEN ACHIEVED TO UNDERSTAND NONLINEAR COMBUSTION INSTABILITIES PRIMARILY BECAUSE OF LACK OF ACCURATE COMPUTATIONAL FLUID DYNAMICS (CFD) METHODOLOGY. PROPOSED EFFERT WILL CONCENTRATE ON DEVELOPING FAST AND TIME- AND SPACE-ACCURATE CFD METHODS FOR EXACT ANALYSIS OF THE NONLINEAR COMBUSTION INSTABILITIES. PROPOSED INNOVATIVE TIME- ACCURATE METHOD WILL BE COMPARED WITH BEST EXISTING NUMERICAL MODELS. THE TECHNIQUES WILL BE EVALUATED ON 1-D ACOUSTIC AND COMBUSTION INSTABILITY PROBLEMS. RESULTS WILL BE COMPARED WITH ANALYTICAL SOLUTIONS AND AVAILABLE EXPERIMENTAL DATA. IN PHASE II, THE BEST TECHNIQUE WILL BE INCORPORATED IN A CFD COMPUTER CODE TO BE USED AS A BASE FORINCORPORATING PHYSICAL MODELS OF TWO-PHASE SPRAY COMBUSTION MODELS.