Survey on key techniques of rocket-based combined-cycle engine in ejector mode

Characteristics of an ejector-jet were investigated experimentally. Evaluation of a new, one-dimensional model of suction performance under the aerodynamic choking condition and observation of mixing conditions through the pseudo-shock were primary subjects of study. Supersonic primary rocket exhaust was simulated by air, and secondary airflow was simulated by nitrogen. Parameters were the ratio of the total pressure of the secondary flow to that of the primary flow, the ratio of the entrance area of the secondary flow to that of the primary flow, and the Mach number of the primary flow. A throttling valve downstream of the mixing region simulated subsonic combustion and subsequent choking, and the throttling created a pseudo-shock ahead of the valve. The suction performance increased with increased total pressure of the secondary flow, the increase of the Mach number of the primary flow, or the increase of the area of the secondary flow. The calculated results on the suction performance agreed well with these measured values. When the gases became subsonic due to throttling, the primary and secondary fluids mixed well through the pseudo-shock and became almost uniform ahead of the downstream choking position. The mixing progressed quickly in the pseudo-shock. Nomenclature A = cross section H = height M = Mach number ˙ m = mass flow rate P = pressure Pt = total pressure r = ratio of the mass flow rate of the secondary flow to that of the primary flow T = temperature Tt = total temperature u =v elocity x = streamwise coordinate from the entrance of the test section y =v ertical coordinate from the primary-flow sidewall z = spanwise coordinate from the center plane of the test section γ = ratio of specific heats ρ = density ω = mass fraction of the secondary flow

Aerodynamic experiment on an ejector-jet

A rocket-based combined-cycle engine prototype demonstrating comprehensive component compatibility and effective mode transition

Numerical analysis of flow features and operation characteristics of a rocket-based combined-cycle inlet in ejector mode

The experimental results from the study of the rocket-ejector mode of a Rocket Based Combined Cycle (RBCC) engine are presented and discussed. The experiments involved systematic flowfield measurements in a two-dimensional variable geometry rocket-ejector system. The rocket-ejector system utilizes a single two-dimensional gaseous oxygen/gaseous hydrogen rocket as the ejector. To gain a thorough understanding of the rocket-ejector's internal fluid mechanic/combustion phenomena, experiments were conducted with both direct-connect and sea-level static configurations for a range of rocket operating conditions. Overall system performance was obtained through global measurements of wall static pressure profiles, heat flux profiles and engine thrust, whereas detailed mixing and combustion information was obtained through Raman spectroscopy measurements of major species (oxygen, hydrogen, nitrogen and water vapor). Rocket-ejector experimental results for both the Diffusion and Afterburning (DAB) and Simultaneous Mixing and Combustion (SMC) geometries are presented here. For the DAB configuration, experiments were conducted for both direct-connect and sea-level static configurations, whereas SMC

Experimental investigation of the rbcc rocket-ejector mode

The rocket based combined cycle (RBCC) approach is a promising concept for advanced space eansportation systems. The RBCC engine concept integrates air-breathing propulsion with rocket propulsion to exploit atmospheric air as the oxidizer during the course of the vehicle trajectory. Although there are numerous design variations, the gamut of concepts includes four flight regimes, viz. rocketejector, ramjet, scramjet and all-rocket. Of these four flight regimes, the rocket-ejector mode, which encompasses the zero to roughly two Mach number range of the flight vehicle, is the least well understood. The goal of the current project is to investigate this mode utilizing a joint experimental/analytical approach. The experimental phase of the program includes studying the mixing and combustion characteristics of the rocket-ejector system utilizing state-of-the-art diagnostic techniques. In this vein, a two-dimensional direct-connect variable geometry rocket-ejector system with enhanced optical access has been designed and fabricated. The system design is based on an earlier study, however, the goal of this program is to systematically increase the range of understanding over a wide range of flow/geometry parameters. In this * Graduate Student, Student Member AIAA ’ Senior Research Associate, Member AK4 * Research Associate, Member AIAA 5 Professor, Member AIAA Copyright

Raman spectroscopy based study of RBCC ejector mode performance

The rocket-ejector mode of a Rocket Based Combined Cycle Engine (RBCC) was studied through a joint experimental/analytical approach A two-dimensional variable geometry rocket-ejector system with enhanced optical access was designed and fabricated for experimentation The rocket-ejector system utilizes a single two-dimensional gaseous oxygen/gaseous hydrogen rocket as the ejector To gain a systematic understanding of the rocket ejector's internal fluid mechanic/combustion phenomena, experiments were conducted with both direct-connect and sea-level static configurations for a range of rocket operating conditions Overall system performance was obtained through Global measurements of wall static pressure profiles, heat flux profiles and engine thrust, whereas detailed mixing and combustion information was obtained through Raman spectroscopy measurements of major species (gaseous oxygen, hydrogen nitrogen and water vapor) These experimental efforts were complemented by Computational Fluid Dynamic (CFD) flowfield analyses

/pdf/focused-experimental-and-analytical-studies-of-the-rbcc-3ubhgmnrwl.pdf

Focused Experimental and Analytical Studies of the RBCC Rocket-Ejector

Experimental and complementary CFD results from the study of the rocket-ejector mode of a Rocket Based Combined Cycle (RBCC) engine are presented and discussed. The experiments involved systematic flowfield measurements in a two-dimensional, variable geometry rocket-ejector system. The rocket-ejector system utilizes a single two-dimensional, gaseous oxygen/gaseous hydrogen rocket as the ejector. To gain a thorough understanding of the rocket-ejector's internal fluid mechanic/combustion phenomena, experiments were conducted with both direct-connect and sea-level static configurations for a range of rocket operating conditions. Overall system performance was obtained through global measurements of wall static pressure profiles, heat flux profiles and engine thrust, whereas detailed mixing and combustion information was obtained through Raman spectroscopy measurements of major species (oxygen, hydrogen, nitrogen and water vapor). The experimental results for both the direct-connect and sea-level static configurations are compared with CFD predictions of the flowfield.

/pdf/experiment-analytical-characterization-of-the-rbcc-rocket-4g3faz0t6d.pdf

Experiment/Analytical Characterization of the RBCC Rocket-Ejector Mode

The status of the RBCC ejector mode research program at Penn State is reviewed. Recent hardware modifications and measurement system improvements are discussed, including the motivation for these changes. Results from a series of tests with a single thruster configuration at a chamber pressure of 200 psia and with an area ratio 3.3 nozzle are presented. These results indicate that the primary (rocket exhaust) and secondary (entrained air) flow streams mix much more rapidly than a previous test series with an area ratio of 6.0 nozzle. Finally, the plans for a test series with a twin thruster configuration are discussed.

https://ntrs.nasa.gov/api/citations/20010020916/downloads/20010020916.pdf

M. Lehman

Papers

Experimental investigation of the rbcc rocket-ejector mode

Raman spectroscopy based study of RBCC ejector mode performance

Focused Experimental and Analytical Studies of the RBCC Rocket-Ejector

Experiment/Analytical Characterization of the RBCC Rocket-Ejector Mode

Status Report on the Penn State RBCC Test Program