Browse Topic: Propellants
Engineers at NASAs Stennis Space Center have developed the HYdrocarbon Propellants Enabling Reproduction of Flows in Rocket Engines (HYPERFIRE), a sub-scale, non-reacting flow test system. HYPERFIRE uses heated ethane to enable physical simulation of rocket engines powered by a broad range of propellants in an inexpensive, accurate, and simple fashion.
As NASA plans for manned missions to Mars, efforts are being made to identify technologies that must be improved to make such trips feasible. Without improvements in valve technologies, propellant and commodity losses will likely make long-duration space missions infeasible. Engineers at NASA's Marshall Space Flight Center have developed a self-aligning poppet for low leakage valves a seat alignment technology that eliminates the need to precisely control interfaces between poppet sealing surfaces and the valve seat seal.
Researchers have used the ancient Japanese art of paper folding to possibly solve a key challenge for outer space travel: how to store and move fuel to rocket engines. They developed an origami-inspired, folded plastic fuel bladder that doesn’t crack at super-cold temperatures and could someday be used to store and pump fuel.
NASA Goddard developed the Cooperative Service Valve (CSV) to facilitate the resupply of media, such as propellants and pressurants, to satellites. The CSV replaces a standard spacecraft fill and drain valve.
Strategies to control solid rocket propellant regression rate require a robust throttling technique applicable to high performance propellant formulations. Currently, several methods to control and throttle either motors or subscale propellant strands exist, including chamber pressure control (e.g. pintle nozzles or rapid depressurization quench), infrared laser irradiation of the burning surface to increase burning rates, development of inherently unstable combustion chamber geometries (producing either local pressure or velocity perturbations), and electrically sensitive hydroxylammonium nitrate (HAN)-based formulations in which burning rate is controlled by a voltage potential. However, these techniques are limited in that they either can only be used with low flame temperature (low specific impulse) propellants, result in low propulsion system mass fraction (pintle), are only capable of producing a single perturbation, or are formulation specific.
Researchers have developed a new propulsion concept for swimming robots that exploits temperature fluctuations in the water for propulsion without the need for an engine, propellant, or power supply.
A highly miniaturized, MR-143, green monopropellant thruster was developed for 1N thrust. Testing indicated the initial catalyst bed heater was insufficient. In subsequent development, the thruster was equipped with a more efficient catalyst bed heater. For reliable ignition of the advanced, non-toxic, AF-M315E monopropellant, the catalyst needs to be preheated. This preheat temperature is much higher than what hydrazine thrusters require. Moreover, the combustion temperature of hydroxyl ammonium nitrate (HAN)-based monopropellants is higher than hydrazine, so the catalyst bed heater must be able to withstand repeated soak-back temperatures.
The scope of this SAE Information Report is to provide general information relative to the nature and use of infrared techniques for nondestructive testing. The document is not intended to provide detailed technical information, but will serve as an introduction to the theory and capabilities of infrared testing and as a guide to more extensive references.
The purpose of this SAE Information Report is to provide basic information on penetrating radiation, as applied in the field of nondestructive testing, and to supply the user with sufficient information so that he may decide whether penetrating radiation methods apply to his particular inspection need. Detailed information references are listed in Section 2.
Putting a satellite into low Earth orbit requires a lot of energy, with ground-launched rockets expending two-thirds of their propellant fighting to get through the atmosphere. Researchers at NASA’s Armstrong Flight Research Center have developed an innovative approach to launching satellites into space from an airborne platform. As with other air-launch approaches, it provides significant flexibility in the location and direction of the launch vehicle. Furthermore, unlike other air-based launch techniques, this system avoids the significant drawbacks related to expensive and complex design/development efforts, difficult maneuvering, risks to crew, and inefficient flight performance.
Structural analysis of solid rocket motors is challenging for several reasons, but the most important of these is the complex behavior of the propellant. The mechanical response of a solid propellant is time and temperature dependent. The complexity of the mathematical analysis of the propellant depends on the loading conditions, but for some loading situations, the linear viscoelasticity assumption is reasonable. In particular, linear viscoelasticity is perhaps the most appropriate material behavior description for use in the simulations of stresses related to storage conditions. Typically, simulations use a viscoelastic model in the form of a Prony series and a Williams–Landel–Ferry (WLF) equation. The parameters in these models are derived from stress relaxation experiments, making the stress relaxation experiment a key viscoelastic test, analogous to the tensile test for linear elastic materials.
In the study of combustion characteristics of liquid rocket fuels, it is customary to either study the combustion of liquid fuel droplets or the combustion of fuel sprays. However, the two are closely related to each other, because in a typical rocket combustion chamber, the burning of droplets, droplet clusters, and fuel sprays occur simultaneously.
This SAE Aerospace Information Report (AIR) presents an overview of the application and control of fixed and variable displacement pumps with the emphasis on the controls most commonly used on variable displacement pumps. It describes various options to control the operation of hydraulic pumps in terms of controlling the pump output pressure and/or flow and assisting in the selection of the pump.
Innovators at NASA's Glenn Research Center have developed several new technological innovations to improve the capability of Hall-effect thrusters, which are used primarily on Earth-orbiting satellites and can also be used for deep-space robotic vehicles. Hall thrusters are susceptible to discharge channel erosion from high-energy ion impingement, which can reduce operational thruster lifetimes. Glenn researchers have developed several approaches to mitigate this problem. One is a magnetic circuit design that minimizes discharge chamber ion impingement. Another successful improvement developed by Glenn is a means of replacing eroded discharge channel material via a channel wall replacement mechanism. A third innovation is a propellant distributor that provides both a high degree of flow uniformity, and shielding from back-sputtered contamination and other potential contaminants. All of these advances work toward increasing the operational lifetime and efficiency of Hall thrusters.
JPL's Microfluidic Electrospray Propulsion (MEP) thruster design is based on a microfabricated electrospray system with a capillary-force-driven feed system that uses indium metal as the propellant. This architecture provides an extremely compact, modular system scalable to a wide range of applications from micro spacecraft to large, space-based telescopes.
Specific impulse (ISP), or simply impulse (change in momentum) per unit amount of propellant consumed, is a measure of rocket and jet engine efficiency. The amount of propellant, or in the case of engine testing at the Stennis Space Center (SSC), cryogen consumed during rocket engine testing must be measured to accurately quantify ISP. One way to determine the amount of cryogen used is to measure the change in cryogen fluid height within a storage/feed tank during testing and then relate the change in height to volume of cryogen consumed. A float system coupled with discrete vertically positioned Reed switches is currently used at the SSC to determine cryogen fluid height and then determine cryogen consumed during a rocket motor test firing. However, the cryogen fluid level within a run tank varies continuously and the switches are placed at discrete locations, limiting the accuracy of this method. If individual switch failures occur, the error increases due to the increased distance
In traditional gridded electrostatic ion thrusters, positively charged ions are generated from a plasma discharge of noble gas propellant and accelerated to provide thrust. A separate electron source, typically a neutralizer cathode that consumes propellant, is required in the propulsion system to neutralize the ion beam after it exits the thruster, thereby maintaining overall charge balance. However, if high-electronegativity propellant gases are used, a plasma discharge can result that consists of both positive and negative ions. Such an electronegative plasma thruster has the ability to generate thrust with a quasi-neutral ion-ion plume, thus allowing for the elimination of the neutralizer cathode subsystem, reduction of propulsion system complexity, and improvement of system lifetime and operational flexibility.
This research compares the spray development and combustion characteristics of jet propellant 8 (JP-8) and iso-paraffinic kerosene (IPK) through a range of diesel engine in-cylinder operating conditions. Non-reacting spray experiments were performed in a constant-pressure flow chamber with 99% nitrogen gas composition at constant temperature (900 K) and densities ranging from 11-56 kg/m3. Near-simultaneous, high-speed Mie and schlieren images of the spray were acquired to measure the liquid and vapor penetration lengths of the non-reacting jet. Reacting experiments, consisting of photodiode measurements and intensified high-speed movies of OH* chemiluminescence, were performed at the same thermodynamic conditions as the non-reacting experiments, except with a 21%/79% oxygen/nitrogen ambient gas composition. Measurements of the rate of injection, issued from a single-hole axial common-rail fuel injector, showed negligible differences between the fuels. The non-reacting liquid length of
A hermetically sealed, normally closed (NC) zero-leak valve has been developed. Prior to actuation, the valve isolates the working fluid in the upstream volume from the downstream volume with a parent metal seal. The valve utilizes the magnetostrictive alloy Terfenol-D for actuation. This alloy experiences a phenomenon known as magnetostriction, i.e., a gross elongation, when exposed to a magnetic field. This elongation fractures the seal within the wetted volume of the valve, opening the valve permanently and establishing fluid flow. The required magnetic field is generated by redundant coils concentric to the Terfenol, but isolated from the working fluid. The response time for this phenomenon to occur and subsequently for actuation is on the order of milliseconds. The wetted volume consists of entirely parent-metal 6Al-4V titanium, compatible with all storable propellants, helium, nitrogen, argon, isopropyl alcohol, and argon. When coupled with the parent metal seal, this design
The Propellant Feed System Analytical Tool (PFSAT) predicts heat leak based on insulation type, installation technique, line supports, penetrations, and instrumentation. It also determines the optimum orifice diameter for an optional thermodynamic vent system (TVS) to counteract heat leak into the feed line, and ensures that the temperature constraints at the end of the feed line are met. PFSAT was developed primarily using Fortran 90 code because of its computational speed and its ability to access directly real fluid property subroutines in the Reference Fluid Thermodynamic and Transport Prop erties (REFPROP) database developed by NIST.
The Space Station Integrated Kinetic Launcher for Orbital Payload Systems (SSIKLOPS), also known as “Cyclops,” deployed the largest satellite ever from the International Space Station (ISS) on November 28, 2014. The satellite, SpinSat, a Naval Research Laboratory (NRL)/Department of Defense Space Test Program (DoD STP) satellite, is pioneering the utilization of electronically controlled solid propellant thrusters as well as acquiring vital atmospheric density data. It is a spherical satellite 22 inches in diameter, weighing 115 pounds, and will remain in orbit for over two years.
Cryogenic fluid management (CFM) is a critical technical area that is needed for the successful development of future space exploration. A key challenge is the storability of LH2, LCH4, and LOX propellants for long durations. The storage tanks must be well insulated to prevent over-pressurization and venting, which lead to unacceptable propellant losses for long-duration missions to Mars and beyond.
An easy and instant method of detection was needed for AF-M315E, a “green” propellant that produces very little vapor. This makes it hard to detect by smell or other active sensors.
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