Tech Briefs

Pyrotechnically Actuated Gas Generator Using Aqueous Methanol

This gas generator ensures successful inflation of a supersonic pilot ballute. NASA’s Jet Propulsion Laboratory, Pasadena, California The largest supersonic parachute ever developed is one of the test articles on the Supersonic Flight Dynamics Test (SFDT) vehicle of the Low Density Supersonic Decelerator (LDSD) project. The typical method for deploying a supersonic parachute from an entry vehicle, by firing it from a mortar, is not viable for this application due to its noncentral location on the vehicle and the associated high reaction force. Instead, the parachute is pulled off the vehicle using the Parachute Deployment Device (PDD). The PDD uses a ballute, a smaller, balloon-like, soft-good drag body that maintains positive internal pressure by ingesting air at supersonic speeds through a set of ram-air inlets. The PDD, being significantly smaller than the supersonic parachute, is deployed using a mortar.

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Deployable Perimeter Truss with Blade Reel Deployment Mechanism

Applications include pop-up tents, deployable deck awnings, and pop-up lawn chairs. NASA’s Jet Propulsion Laboratory, Pasadena, California Solar sail technology depends heavily on the total surface area of the sail. In other words, minimizing mass and volume of its support structure is the main objective, particularly when it comes to launch configuration, i.e. mass, volume constraints, etc. There is a need to develop a low-cost concept of a deployable support structure that can stow in the EELV Secondary Payload Adapter (ESPA) volume, and carries as much sail material as possible. This structure must then be able to deploy the sail material out, and provide the surface area needed.

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Cantera Integration with T-MATS

John H. Glenn Research Center, Cleveland, Ohio The Toolbox for the Modeling and Analysis of Thermodynamic Systems (TMATS) software package is a library of building blocks that can be assembled to represent any thermodynamic system in the Simulink® (MathWorks, Inc.) environment. These elements, along with a Newton Raphson solver (also provided as part of the T-MATS package), enable users to create models of a wide variety of systems. The updated version of T-MATS (v1.1.1) includes the integration of Cantera, an open source thermodynamic simulation tool. T-MATS was initially described in detail in LEW-19165-1, "Toolbox for Modeling and Analysis of Thermodynamic Systems (T-MATS)", Software Tech Briefs (September 2014), p. 11.

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Rocket Sled Parachute Design Verification

This test architecture helps verify parachute designs for Mars and Earth applications that are too large to fit inside existing wind tunnels. NASA’s Jet Propulsion Laboratory, Pasadena, California Historically, parachutes have been load-tested by various methods including release from an aircraft, deploying in a wind tunnel, dragging through water, and shooting out of an air cannon. Each type of testing has its own advantages and drawbacks. Due to the loading mechanics particular to parachutes deploying in a very thin atmosphere, none of the testing methods was appropriate for testing the next generation of Mars’ full-scale parachutes.

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Reynolds-Averaged Navier-Stokes Integration for Shock Noise (RISN)

Langley Research Center, Hampton, Virginia Reynolds-averaged Navier-Stokes (RANS) Integration for Shock- Noise (RISN) is a computer program that evaluates acoustic analogies to predict jet noise. Jet noise is due to turbulence from the chaotic flow within the exhaust of a rocket or air-breathing jet engine. The source of jet noise is the turbulent mixing of the exhaust, screech (tones) due to a feedback loop between the semi-periodic shock cells and the nozzle, and broadband shockassociated noise due to the interaction of the turbulence with the shock cells. Acoustic analogies are rearrangements of the Navier-Stokes equations into a left-hand-side propagation operator and a right-hand-side equivalent noise source. RISN is capable of predicting the noise spectrum from all source components within supersonic offdesign jets. Furthermore, the noise from three-dimensional and axisymmetric nozzles can be predicted as long as a steady RANS solution is present. RISN predictions are based upon integrations of computational fluid dynamic solutions. Predictions consist of the spectral density at observers positioned around the nozzle exit.

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Regeneratively Cooled Porous Media Jacket

Cooling jackets were developed comprising impermeable inner and outer walls. Lyndon B. Johnson Space Center, Houston, Texas A non-toxic nitrous oxide fuel blend (NOFB) monopropellant with a high adiabatic flame temperature reaching and probably exceeding 3,450 K and a very high thermal decomposition limit (>390 °C) is under development. To design an optimal rocket engine that can handle the high adiabatic temperature during continuous rocket thruster operations, a regeneratively cooled rocket engine is desirable, but the regenerative jacket temperatures must remain well below the monopropellant’s thermal decomposition limit. In fact, the entire engine during operation should ideally remain well below the thermal ignition limit so that heat soak-back cannot potentially decompose the monopropellant following an engine restart.

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Multi-Pulse Motor (MPM) Designed for Use with Electric Solid Propellants

The solid rocket motor can be electrically pulsed a number of times to produce a required thrust or impulse bit. Marshall Space Flight Center, Alabama The multi-pulse motor is a solid-propellant rocket motor that is able to produce a number of pulses for various thrust levels (5 to 30 pulses and thrusts between 0.25 and 1.5 N, depending on electric power delivery system) and can be turned on and off through the application of electrical power.

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