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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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NASA NTRS2010

2010 JPC Abstract: Ares I First Stage Propulsion System Status

In November 2005, NASA created the Constellation Program to develop an entirely new fleet of spacecraft to include the Ares I Crew Launch Vehicle and Ares V Cargo Launch vehicles. This mission architecture included the Orion capsule (which would be used to transport astronauts to low-Earth orbit and beyond), the Altair lunar lander, and an Earth departure stage. The Ares First Stage Team has made significant progress on the design of a propulsion system to meet the objectives of the Constellation Program. Work on a first stage element propulsion system capable of lofting a new fleet of spacecraft is well underway. To minimize technical risks and development costs, the Solid Rocket Boosters (SRBs) of Shuttle served as a starting point in the design of a new motor that would meet the requirements of those new vehicles. This new propulsive element will provide greater total impulse utilizing a fifth segment to loft a safer, more powerful fleet of space flight vehicles. Performance requirements, basic architecture, and obsolescence issues were all factors in determining the new first stage element design and configuration. Early efforts focused on creating designs that would be capable of supporting the requisite loads and environments. While the motor casings are Shuttle legacy, because of Ares I s unique in-line configuration, the first stage will require entirely new forward structures (forward skirt, forward skirt extension, aeroshell, and frustum) and a modified systems tunnel. The use of composites facilitated a change in the geometry, which in turn afforded the ability to focus strength where it was needed without additional mass. The Ares First Stage rocket motor casting tooling was designed and built to achieve a propellant grain geometry that produces the specific required ballistic profile. The new propellant formulation is a polybutadiene acrylonitrile (PBAN) copolymer, which has been modified to attain the desired burn rate and retain adequate tailoring capability.

Priskos, Alex S.↗
NASA NTRS1976

Three-dimensional finite element analysis of acoustic instability of solid propellant rocket motors

A three dimensional finite element solution of the acoustic vibration problem in a solid propellant rocket motor is presented. The solution yields the natural circular frequencies of vibration and the corresponding acoustic pressure mode shapes, considering the coupled response of the propellant grain to the acoustic oscillations occurring in the motor cavity. The near incompressibility of the solid propellant is taken into account in the formulation. A relatively simple example problem is solved in order to illustrate the applicability of the analysis and the developed computer code.

Hackett, R. M.↗
NASA NTRS2000

Environmentally Compliant Disposal Method for Heavy Metal Containing Propellants

ABSTRACT An environmentally friendly, cost effective technology has been developed and demonstrated by a team of Naval Air Warfare Center and Lockheed Martin personnel to dispose of Shillelagh solid rocket motor propellants. The Shillelagh is a surface to surface anti-tank weapon approaching the end of its service life. The current demilitarization process employs open detonation, but the presence of lead stearate in the N5 propellant grain motivated the need for the development of an environmentally friendly disposal method. Contained burning of the propellant followed by propellant exhaust processing was chosen as the disposal methodology. The developmental test bed, completed in February 1998, is inexpensive and transportable. Contained burning of Shillelagh propellants posed two technical hurdles: 1) removal of the sub micron lead and cadmium particulate generated during combustion, and 2) secondary combustion of the significant quantifies of carbon monoxide and hydrogen. A firing chamber with a stepped nozzle, air injection, and active ignition was developed to combust the carbon monoxide and hydrogen in real time. The hot gases and particulates from the combustion process are completely contained within a gas holder. The gases are subsequently cooled and routed through a treatment facility to remove the heavy metal particulate. Results indicate that the lead and cadmium particulates are removed below their respective detection limits (2 micro-g/cu m & 0.2 micro-g/cu m) of the analytical procedures employed and that the carbon monoxide and hydrogen levels have been reduced well below the lower flammability limits. Organic concentrations, principally benzene, are I ppm or less. A semi-automated machine has been developed which can rapidly prepare Shillelagh missiles for the contained burn facility. This machine allows the contained burn technology to be more competitive with current open bum open detonation disposal rates.

Decker, M. W.↗
NASA NTRS1977

Reduced variable technique for predicting grain behavior

The use of reduced variables to account for the time-temperature dependence of the relaxation modulus is a standard and universally adopted technique in the stress analysis of solid propellant grains. Recent work has suggested that the reduced variable technique can also be used to account for the dependence of the relaxation modulus on the crosslink density of an elastomer system. By combining variables, it is now possible to determine the relaxation modulus as a function of both mechanical and chemical parameters over a long period of time. The problems involved, the pitfalls to be avoided, and suggested techniques to be used in acquiring data are discussed.

Lewis, G. W.↗
NASA NTRS1980

Particle behavior in solid propellant rockets

The use of holography, high speed motion pictures, light scattering measurements, and post-fire particle collection/scanning electron microscopic examination to study the combustion of composite solid propellants is discussed. The relative advantages and disadvantages of the different experimental techniques for obtaining two-phase flow characteristics within the combustion environment of a solid propellant grain are evaluated. Combustion bomb studies using high speed motion pictures and post-fire residue analysis were completed for six low metal content propellants. Resolution capabilities and the relationships between post-fire residue and motion picture data are determined. Initial testing using a holocamera together with a 2D windowed motor is also described.

Netzer, D. W.↗
NASA NTRS1981

Shuttle solid rocket motor nozzle alternate ablative evaluation

A series of subscale tests are shown to suggest that a lower-cost ablative material than the rayon-based carbon ablative currently used in the Space Shuttle Solid Rocket Motor (SRM) may be used as a substitute. Six such ablatives with outstanding performance characteristics, using spun PAN and continuous pitch and PAN fibers instead of the present, continuous rayon, were identified in the course of tests with HTPB/AL/AP solid propellant grains with a burn time of 12 sec. The test nozzle features an initial throat diameter of 2.2 in. and a 6.1 expansion ratio. In addition to nozzle structural feature drawings, extensive test data tables and propellant formulation and properties tables are provided.

Powers, L. B.↗
NASA NTRS2002

Portable propellant cutting assembly, and method of cutting propellant with assembly

A propellant cutting assembly and method of using the assembly to cut samples of solid propellant in a repeatable and consistent manner is disclosed. The cutting assembly utilizes two parallel extension beams which are shorter than the diameter of a central bore of an annular solid propellant grain and can be loaded into the central bore. The assembly is equipped with retaining heads at its respective ends and an adjustment mechanism to position and wedge the assembly within the central bore. One end of the assembly is equipped with a cutting blade apparatus which can be extended beyond the end of the extension beams to cut into the solid propellant.

Sharp, Roger A.↗
NASA NTRS1965

The Dynamics of Solid Propellant Rocket Motors

From the point of view of dynamics, a solid propellant rocket motor is a unique structure in that it is composed of a substantial mass of propellant material case-bonded to a relatively massless, thin-walled cylinder. The mechanical properties of the propellant are such that it contributes little to the stiffness of the composite structure but it does contribute to the dynamic characteristics of the structure because of its mass. Furthermore, due to the viscoelastic character of the propellant, it can be expected to provide considerable damping to the system. At this point in the development of the art of design of solid propellant rocket motors there are no clear-cut or well-founded methods to evaluate quantitatively the contributions of the propellant to the dynamic responses of the composite structure. It is clear that unless such methods are devised, it will be difficult to arrive at accurate missile designs. In this paper a survey of the dynamic problems of solid propellant rocket motors is presented starting from the simplest model thereof and proceeding, step-by-step, to the consideration of more sophisticated and realistic models. The consideration is restricted to infinitesimal deformations of propellant grains with linear mechanical properties. Substantial progress has been achieved towards the solution of many important dynamical problems. We shall attempt to summarize the pertinent developments and indicate along which lines we feel future study should proceed. A few illustrative solutions are included in areas wherein progress has been substantial.

DYNAMIC RESPONSE↗
NASA NTRS2015

Solid Rocket Motor Combustion Instability Modeling in COMSOL Multiphysics

Combustion instability modeling of Solid Rocket Motors (SRM) remains a topic of active research. Many rockets display violent fluctuations in pressure, velocity, and temperature originating from the complex interactions between the combustion process, acoustics, and steady-state gas dynamics. Recent advances in defining the energy transport of disturbances within steady flow-fields have been applied by combustion stability modelers to improve the analysis framework [1, 2, 3]. Employing this more accurate global energy balance requires a higher fidelity model of the SRM flow-field and acoustic mode shapes. The current industry standard analysis tool utilizes a one dimensional analysis of the time dependent fluid dynamics along with a quasi-three dimensional propellant grain regression model to determine the SRM ballistics. The code then couples with another application that calculates the eigenvalues of the one dimensional homogenous wave equation. The mean flow parameters and acoustic normal modes are coupled to evaluate the stability theory developed and popularized by Culick [4, 5]. The assumption of a linear, non-dissipative wave in a quiescent fluid remains valid while acoustic amplitudes are small and local gas velocities stay below Mach 0.2. The current study employs the COMSOL multiphysics finite element framework to model the steady flow-field parameters and acoustic normal modes of a generic SRM. The study requires one way coupling of the CFD High Mach Number Flow (HMNF) and mathematics module. The HMNF module evaluates the gas flow inside of a SRM using St. Robert's law to model the solid propellant burn rate, no slip boundary conditions, and the hybrid outflow condition. Results from the HMNF model are verified by comparing the pertinent ballistics parameters with the industry standard code outputs (i.e. pressure drop, thrust, ect.). These results are then used by the coefficient form of the mathematics module to determine the complex eigenvalues of the Acoustic Velocity Potential Equation (AVPE). The mathematics model is truncated at the nozzle sonic line, where a zero flux boundary condition is self-satisfying. The remaining boundaries are modeled with a zero flux boundary condition, assuming zero acoustic absorption on all surfaces. The results of the steady-state CFD and AVPE analyses are used to calculate the linear acoustic growth rate as is defined by Flandro and Jacob [2, 3]. In order to verify the process implemented within COMSOL we first employ the Culick theory and compare the results with the industry standard. After the process is verified, the Flandro/Jacob energy balance theory is employed and results displayed.

Fischbach, Sean R.↗
NASA NTRS2015

Solid Rocket Motor Combustion Instability Modeling in COMSOL Multiphysics

Combustion instability modeling of Solid Rocket Motors (SRM) remains a topic of active research. Many rockets display violent fluctuations in pressure, velocity, and temperature originating from the complex interactions between the combustion process, acoustics, and steady-state gas dynamics. Recent advances in defining the energy transport of disturbances within steady flow-fields have been applied by combustion stability modelers to improve the analysis framework. Employing this more accurate global energy balance requires a higher fidelity model of the SRM flow-field and acoustic mode shapes. The current industry standard analysis tool utilizes a one dimensional analysis of the time dependent fluid dynamics along with a quasi-three dimensional propellant grain regression model to determine the SRM ballistics. The code then couples with another application that calculates the eigenvalues of the one dimensional homogenous wave equation. The mean flow parameters and acoustic normal modes are coupled to evaluate the stability theory developed and popularized by Culick. The assumption of a linear, non-dissipative wave in a quiescent fluid remains valid while acoustic amplitudes are small and local gas velocities stay below Mach 0.2. The current study employs the COMSOL Multiphysics finite element framework to model the steady flow-field parameters and acoustic normal modes of a generic SRM. This work builds upon previous efforts to verify the use of the acoustic velocity potential equation (AVPE) laid out by Campos. The acoustic velocity potential (psi) describing the acoustic wave motion in the presence of an inhomogeneous steady high-speed flow is defined by, del squared psi - (lambda/c) squared psi - M x [M x del((del)(psi))] - 2((lambda)(M)/c + M x del(M) x (del)(psi) - 2(lambda)(psi)[M x del(1/c)] = 0. with M as the Mach vector, c as the speed of sound, and λ as the complex eigenvalue. The study requires one way coupling of the CFD High Mach Number Flow (HMNF) and mathematics module. The HMNF module evaluates the gas flow inside of a SRM using St. Robert's law to model the solid propellant burn rate, slip boundary conditions, and the supersonic outflow condition. Results from the HMNF model are verified by comparing the pertinent ballistics parameters with the industry standard code outputs (i.e. pressure drop, axial velocity, exit velocity). These results are then used by the coefficient form of the mathematics module to determine the complex eigenvalues of the AVPE. The mathematics model is truncated at the nozzle sonic line, where a zero flux boundary condition is self-satisfying. The remaining boundaries are modeled with a zero flux boundary condition, assuming zero acoustic absorption on all surfaces. The one way coupled analysis is perform four times utilizing geometries determined through traditional SRM modeling procedures. The results of the steady-state CFD and AVPE analyses are used to calculate the linear acoustic growth rate as is defined by Flandro and Jacob. In order to verify the process implemented within COMSOL we first employ the Culick theory and compare the results with the industry standard. After the process is verified, the Flandro/Jacob energy balance theory is employed and results displayed.

Fischbach, S. R.↗
NASA NTRS1969

Propulsion Division

Solid propellant grain analyses and combustion optimization problems

Source record↗
NASA NTRS1968

Ignition problems in solid-propellant rockets

Methods of analysis of solid rocket motor ignition and Igniter performance are given. Ignition and ignition Internal ballistic performance are treated beginning with the combustion of the igniter pyrotechnic after the Initiator has functioned. The ignition phenomenon is followed through the (a) igniter ballistic performance, (b) pre-ignition motor port volume pressurization and convective heat transfer (c) motor propellant grain ignition, and (d) subsequent motor ballistics to equilibrium motor operating pressure.

B E Paul↗
NASA NTRS1973

NASTRAN cyclic symmetry capability

A development for NASTRAN which facilitates the analysis of structures made up of identical segments symmetrically arranged with respect to an axis is described. The key operation in the method is the transformation of the degrees of freedom for the structure into uncoupled symmetrical components, thereby greatly reducing the number of equations which are solved simultaneously. A further reduction occurs if each segment has a plane of reflective symmetry. The only required assumption is that the problem be linear. The capability, as developed, will be available in level 16 of NASTRAN for static stress analysis, steady state heat transfer analysis, and vibration analysis. The paper includes a discussion of the theory, a brief description of the data supplied by the user, and the results obtained for two example problems. The first problem concerns the acoustic modes of a long prismatic cavity imbedded in the propellant grain of a solid rocket motor. The second problem involves the deformations of a large space antenna. The latter example is the first application of the NASTRAN Cyclic Symmetry capability to a really large problem.

Macneal, R. H.↗
NASA NTRS1981

High temperature propellant development

It is reported that the neccessary technology has been developed and demonstrated for the manufacture of heat-sterilizable solid propellants which meet specific ballistic goals. It is shown that: (1) phosphate doping of ammonium perchlorate significantly enhances the thermal stability of the substance; (2) grinding the ammonium perchlorate to reduce particle size further increases thermal stability; and (3) unsaturated polymers such as the polybutadienes can be successfully used in a heat-sterilizable propellant system. Among the topics considered by the study are oxidizers, dopants, binders, and the thermal cycling of 70 lb and 600 lb propellant grains.

Anderson, F. A.↗
NASA NTRS1989

Cold Flow Determination of the Internal Flow Environment Around the Submerged TVC Nozzle for the Space Shuttle SRM

A series of subscale cold flow tests was performed to quantify the gas flow characteristics at the aft end of the Space Shuttle Solid Rocket Motor. This information was used to support the analyses of the redesigned nozzle/case joint. A portion of the thermal loads at the joint are due to the circumferential velocities and pressure gradients caused primarily by the gimbaling of the submerged nose TVC nozzle. When the nozzle centerline is vectored with respect to the motor centerline, asymmetries are set up in the flow field under the submerged nozzle and immediately adjacent to the nozzle/case joint. Specific program objectives included: determination of the effects of nozzle gimbal angle and propellant geometry on the circumferential flow field; measurement of the static pressure and gas velocities in the vicinity of the nozzle/case joint; use of scaling laws to apply the subscale cold flow data to the full scale SRM; and generation of data for use in validation of 3-D computational fluid dynamic, CFD, models of the SRM flow field. These tests were conducted in the NASA Marshall Space Flight Center Airflow Facility with a 7.5 percent scale model of the aft segment of the SRM. Static and dynamic pressures were measured in the model to quantify the flow field. Oil flow data was also acquired to obtain qualitative visual descriptions of the flow field. Nozzle gimbal angles of 0, 3.5, and 7 deg were used with propellant grain configurations corresponding to motor burn times of 0, 9, 19, and 114 seconds. This experimental program was successful in generating velocity and pressure gradient data for the flow field around the submerged nose nozzle of the Space Shuttle SRM at various burn times and gimbal angles. The nature of the flow field adjacent to the nozzle/case joint was determined with oil droplet streaks, and the velocity and pressure gradients were quantified with pitot probes and wall static pressure measurements. The data was applied to the full scale SRM thru a scaling analysis and the results compared well with the 3-D computational fluid dynamics computer model.

Whitesides, R. H.↗