THE HANSON RESEARCH GROUP IN THE HIGH TEMPERATURE GASDYNAMICS LABORATORY OF THE MECHANICAL ENGINEERING DEPARTMENT AT STANFORD UNIVERSITY PROPOSES COLLABORATIVE FUNDAMENTAL RESEARCH UNDER THE DIRECTION OF DR. GEORGE RAICHE CHIEF OF THE THERMOPHYSICS FACILITIES BRANCH AT NASA-AMES RESEARCH CENTER (NASA-ARC). THE GOAL OF THIS WORK IS THE APPLICATION OF NEW OPTICAL DIAGNOSTIC MEASUREMENTS TO INVESTIGATE THE EFFECT OF NEW AND EXISTING INJECTION STRATEGIES ON MIXING IN ARC-HEATERS AT THE NASAARC ARC-JET COMPLEX. THIS WORK WILL LEVERAGE PREVIOUS SUCCESSFUL COLLABORATIONS BETWEEN STANFORD AND NASA-ARC WHERE LASER ABSORPTION SPECTROSCOPY (LAS) MEASUREMENTS OF THE THERMAL POPULATION OF ELECTRONIC-EXCITED ATOMIC OXYGEN WAS USED TO DETERMINE TIME-RESOLVED GAS TEMPERATURE IN THE 60MW ARC-HEATER OF THE INTERACTION HEATING FACILITY (IHF-60MW). MEASUREMENTS ALONG MULTIPLE LINES-OF-SIGHT ACROSS THE ADDGAS PLENUM OF THE ARC-HEATER IDENTIFIED SIGNIFICANT NONUNIFORMITIES AND ASYMMETRIES IN THE FLOW. THE OBSERVED PHENOMENA LED TO A HYPOTHESIS OF INSUFFICIENT ADD-AIR MIXING AND ULTIMATELY A REDESIGNED ADD-AIR PLENUM WITH THE INCLUSION OF A MIXING VOLUME TO IMPROVE MIXING. SUBSEQUENT OPTIMIZED LAS MEASUREMENTS HAVE SINCE VERIFIED SIGNIFICANTLY IMPROVED MIXING AND THUS IMPROVED FLOW UNIFORMITY. THE WORK PROPOSED HERE WILL FOCUS SPECIFICALLY ON TWO SEGMENTED ARC-HEATERS; THE 10 MW ARC-HEATER IN THE AERODYNAMIC HEATING FACILITY (AHF-10MW) AND THE 60MW ARC-HEATER OF THE INTERACTION HEATING FACILITY (IHF-60MW). THE PROPOSED EFFORT IN EACH FACILITY WILL HAVE A DISTINCT BUT RELATED SCIENTIFIC OBJECTIVE: OBJECTIVE 1: AHF-10MW MEASUREMENTS OF THE EFFECT OF MULTI-COMPONENT AND PRE-MIXED TEST GAS INJECTION ON FLOW UNIFORMITY OBJECTIVE 2: IHF-60MW MEASUREMENTS OF THE EFFECT OF IMPROVED ADD-AIR INJECTION STRATEGIES ON FLOW UNIFORMITY THE AHF-10MW ARC-HEATER OFFERS A UNIQUE TEST-GAS INJECTION STRATEGY WITH THE CAPABILITY TO MIX TWO INDIVIDUAL TEST-GAS COMPONENTS DIRECTLY IN THE ARC-COLUMN. THE FLEXIBILITY OFFERED BY THIS INJECTION STRATEGY ALSO RAISES MANY QUESTIONS REGARDING BOTH THE TEMPERATURE AND COMPOSITIONAL UNIFORMITY OF THE TEST FLOW. AS THE PRIMARY RESEARCH EFFORT (OBJECTIVE 1) STANFORD PROPOSES MEASUREMENTS OF THE FLOW TEMPERATURE AND COMPOSITIONAL DISTRIBUTION WITHIN THE AHF-10MW ARC-HEATER IN ORDER TO INVESTIGATE THE IMPACT OF THE TWO-COMPONENT TEST-GAS INJECTION STRATEGY ON FLOW UNIFORMITY. IN ADDITION TO THE NEW RESEARCH THRUST PROPOSED IN THE AHF-10MW CONTINUED INVESTIGATIONS IN THE IHF-60MW ARE ALSO PROPOSED. IT HAS BEEN OBSERVED THAT THE ADDITION OF A MIXING VOLUME IMPROVED FLOW UNIFORMITY BUT ALSO REDUCED MAXIMUM TOTAL FLOW ENTHALPY FOR THE FACILITY. IT IS IMPORTANT THAT THIS ENTHALPY LOSS IS RECOVERED AND IT IS HYPOTHESIZED THAT THE ADDITIONAL LENGTH INTRODUCED BY THE MIXING VOLUME HAS INCREASED HEAT LOSS TO THE WATER-COOLED COPPER WALLS. PRESENTLY NEW ADD-AIR INJECTION STRATEGIES ARE UNDER DEVELOPMENT TO IMPROVE MIXING AND REDUCE THE REQUIRED MIXING VOLUME LENGTH. AS A SECONDARY RESEARCH EFFORT (OBJECTIVE 2) STANFORD PROPOSES MEASUREMENTS TO CHARACTERIZE THE FLOW TEMPERATURE DISTRIBUTION OVER THE LENGTH OF THE MIXING VOLUME IN ORDER TO UNDERSTAND THE INFLUENCE OF NEW ADD-AIR INJECTION STRATEGIES ON FLOW UNIFORMITY AND ENTHALPY LOSS.