Heat and gas release measurements on liquid hypergolic propellants
Liquid hypergolic propellants heat and gas release determination by calorimetric and PVT measurements, using impinging free jets for propellant mixing
Rodriguez, S. E.↗
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Orbital operations study. Appendix A: Interactivity analysis
Supplemental analyses conducted to verify that safe, feasible, design concepts exist for accomplishing the attendant interface activities of the orbital operations mission are presented. The data are primarily concerned with functions and concepts common to more than one of the interfacing activities or elements. Specific consideration is given to state vector update, payload deployment, communications links, jet plume impingement, attached element operations, docking and structural interface assessment, and propellant transfer.
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Orbiter operations in close proximity to free-flying satellites or formation flying in space
The seventh orbital flight of the Space Shuttle had as one of its primary objectives the testing of the vehicle's capability for proximity operations (defined as anytime the Orbiter is within 1000 feet of another satellite). The goals of these tests were to obtain flight data on different techniques for separation from, stationkeeping with, and approach and capture of a free-flying satellite. This included the acquisition of data on technique evaluation as to propellant usage, time required, crew workload, plume disturbance to the payload by the reaction control system, and jet plume impingement. The tests were also to provide data on the rendezvous radar and optical sighting devices performance in this environment. It is concluded that the Orbiter proved to be a very responsive vehicle that ws straightforward to fly in the vicinity of another satellite given the proper experience base with ground simulations.
Crippen, R. L.↗
Formationkeeping of Spacecraft via Differential Drag
This paper examines the use of differential drag in the formationkeeping of spacecraft. In many future space missions one satellite will be required to fly in a specific position with respect to another satellite; this action is referred to as formationkeeping. In this study, differential drag is the difference in drag between the two satellites. Reasons to use differential drag as an actuator for formationkeeping include the avoidance of jet plume impingement effects on closely spaced satellites and possible fuel savings. The equations of relative motion between the two satellites are derived and a mathematical transformation is made to reduce the formationkeeping problem to the simultaneous solution of a double integrator and a harmonic oscillator. A two-part control law is developed that simultaneously and dependently solves the double oscillator and harmonic integrator. Results are presented of eight test cases being driven to a target position; two different simulations are used. The validity of assumptions made in the derivation of the control law is examined in the comparison of similar test cases run through different simulations. The control law developed can drive a satellite from an initial position to a target position and maintain the satellite at that location.
Leonard, Carolina Lee↗
Forced convection heat transfer to air/water vapor mixtures
Heat transfer coefficients were measured using both dry air and air/water vapor mixtures in the same forced convection cooling test rig (jet array impingement configurations) with mass ratios of water vapor to air up to 0.23. The primary objective was to verify by direct experiment that selected existing methods for evaluation of viscosity and thermal conductivity of air/water vapor mixtures could be used with confidence to predict heat transfer coefficients for such mixtures using as a basis heat transfer data for dry air only. The property evaluation methods deemed most appropriate require as a basis a measured property value at one mixture composition in addition to the property values for the pure components.
Richards, D. R.↗
Propellant vaporization as a criterion for rocket-engine design : experimental effect of fuel temperature on liquid-oxygen - heptane performance
Characteristic exhaust velocity of a 200-pound-thrust rocket engine was evaluated for fuel temperatures of -90 degrees, and 200 degrees f with a spray formed by two impinging heptane jets reacting in a highly atomized oxygen atmosphere. Tests covered a range of mixture ratios and chamber lengths. The characteristic exhaust-velocity efficiency increased 2 percent for a 290 degree f increase in fuel temperature. This increase in performance can be compared with that obtained by increasing chamber length by about 1/2 inch. The result agrees with the fuel-temperature effect predicted from an analysis based on droplet evaporation theory. Mixture ratio markedly affected characteristic exhaust velocity efficiency, but total flow rate and fuel temperature did not.
Heidmann, M F↗
Rendezvous and Proximity Operations of the Space Shuttle
Space Shuttle rendezous missions presented unique challenges that were not fully recognized when the Shuttle was designed. Rendezvous targets could be passive (i.e., no lights or transponders), and not designed to facilitate Shuttle rendezvous, proximity operations and retrieval. Shuttle reaction control system jet plume impingement on target spacecraft presented induced dynamics, structural loading and contamination concerns. These issues, along with limited forward reaction control system propellant, drove a change from the Gemimi/Apollo coelliptic profile heritage to a stable orbit profile, and the development of new proximity operations techniques. Multiple scientific and on-orbit servicing missions and crew exchange, assembly and replinishment flights to Mir and to the International Space Station drove further profile and piloting technique changes, including new relative navigation sensors and new computer generated piloting cues.
Goodman, John L.↗
Rendezvous and Proximity Operations of the Space Shuttle
Space Shuttle rendezvous missions present unique challenges that were not fully recognized when the Shuttle was designed. Rendezvous targets could be passive (i.e., no lights or transponders), and not designed to facilitate Shuttle rendezvous, proximity operations, and retrieval. Shuttle reaction control system jet plume impingement on target spacecraft presented induced dynamics, structural loading, and contamination concerns. These issues, along with limited reaction control system propellant in the Shuttle nose, drove a change from the legacy Gemini/Apollo coelliptic profile to a stable orbit profile, and the development of new proximity operations techniques. Multiple scientific and on-orbit servicing missions, and crew exchange, assembly and replenishment flights to Mir and to the International Space Station drove further profile and piloting technique changes. These changes included new proximity operations, relative navigation sensors, and new computer generated piloting cues. However, the Shuttle's baseline rendezvous navigation system has not required modification to place the Shuttle at the proximity operations initiation point for all rendezvous missions flown.
Goodman, John L.↗
Reaction Control System Design Considerations for Mars Entry Vehicles
The next generation of Mars exploration landers must precisely deliver scientific payloads to sites of interest, unlike previous Mars missions. The past missions, such as Viking and Pathfinder, performed landings to within 100s of kilometers from their targets using an unguided atmospheric entry. Guided entry of a capsule with a relatively high lift-to-drag ratio will allow landing to within 10s of kilometers from the target with a significantly more massive payload. Successful guided entry requires the use of a reaction control system (RCS) for both attitude correction and entry guidance maneuvers. Various aspects of the entry, descent and landing (EDL) system performance may be impacted by the operation of the RCS during entry. This paper illustrates the risks that arise from the gasdynamic interaction of the entry vehicle (EV) and RCS, and which require attention in the areas of aerodynamics and control, and aerothermal environments. This paper will review the methods to address the design challenges associated with integration of RCS into the atmospheric entry system. Among these challenges is the analysis of the potential for the aerodynamic interference due to both the direct jet plume impingement and more complex plume interactions with the wake flow. These interactions can result in enhanced aeroheating, requiring that a different approach to the thermal protection system (TPS) selection and sizing be used. The recent findings for Mars Science Laboratory and Mars Phoenix will be presented to help illustrate some of the phenomena. Current design solutions will be discussed.
Dyakonov, Artem A.↗
Numerical Analysis of Rocket Exhaust Cratering
Supersonic jet exhaust impinging onto a flat surface is a fundamental flow encountered in space or with a missile launch vehicle system. The flow is important because it can endanger launch operations. The purpose of this study is to evaluate the effect of a landing rocket s exhaust on soils. From numerical simulations and analysis, we developed characteristic expressions and curves, which we can use, along with rocket nozzle performance, to predict cratering effects during a soft-soil landing. We conducted a series of multiphase flow simulations with two phases: exhaust gas and sand particles. The main objective of the simulation was to obtain the numerical results as close to the experimental results as possible. After several simulating test runs, the results showed that packing limit and the angle of internal friction are the two critical and dominant factors in the simulations.
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Jet-Surface Interaction Test: Phased Array Noise Source Localization Results
Subsonic jets are relatively simple. The peak noise source location gradually moves upstream toward the nozzle as frequency increases. 2) Supersonic jets are more complicated. The peak noise source location moves downstream as frequency increases through a BBSN hump. 3) In both subsonic and supersonic jets the peak noise source location corresponding to a given frequency of noise moves downstream as jet Mach number increases. 4) The noise generated at a given frequency in a BBSN hump is generated by a small number of shocks, not from all the shocks at the same time. 5) Single microphone spectrum levels decrease when the noise source locations measured with the phased array are blocked by a shielding surface. This consistency validates the phased array data and the stationary monopole source model used to process it. 6) Reflecting surface data illustrate that the law of reflection must be satisfied for noise to reflect off a surface toward an observer. Depending on the relative locations of the jet, the surface and the observer only some of the jet noise sources may satisfy this requirement. 7) The low frequency noise created when a jet flow impinges on a surface comes primarily from the trailing edge regardless of the axial extent impacted by the flow.
Podboy, Gary↗
Popping phenomena with the hydrazine nitrogen-tetroxide propellant system.
The propellant spray resulting from the impingement of liquid jets of hydrazine and nitrogen tetroxide has been studied at atmospheric pressure by means of streak photography. The streak photographs show periodic small explosions that originate near the impingement point and propagate through the propellant spray at velocities of 3000 to 5000 fps, consuming all propellant droplets over a distance of up to 6 in. Typical streak photographs are presented. The frequency of the explosions or pops ranged up to several hundred cps, and could be controlled by varying the contact time in the liquid phase. Below a minimum threshold contact time, popping did not take place. At high values of contact time, the popping rate was controlled by the transit time of the free jet before impingement. Flashing of the oxidizer prior to impingement prevented popping under certain conditions. It is postulated that popping is initiated by liquid phase reactions. A mechanism for the occurrence of popping and its relation to reactive stream separation is suggested.
Houseman, J.↗
Assessment of Erosion Resistance of Coated Polymer Matrix Composites for Propulsion Applications
The erosion behavior of tungsten carbide-cobalt (WC-Co) coated and uncoated polymer matrix composites (PMCs) was examined with solid particle impingement using air jets. Erosion tests were conducted with Arizona road dust impinging at 20 degrees, 60 degrees, and 90 degrees angles at a velocity of 229 meters per second at both 294 and 366 K. Noncontact optical profilometry was used to measure the wear volume loss. Results indicate that the WC-Co coating enhanced erosion resistance and reduced erosion wear volume loss by a factor of nearly 2. This should contribute to longer wear lives, reduced related breakdowns, decreased maintenance costs, and increased product reliability.
Miyoshi, Kazuhisa↗
Peak axial-velocity decay with multi-element rectangular and triangular nozzles
The aircraft noise created by the impingement of engine exhaust jet of STOL aircraft with externally blown flaps is discussed. It was determined that the jet-flap interaction noise can be lowered by reducing the impinging velocity of the jet. The reduction must occur at a specific distance from the flap to be effective. The peak axial-velocity decay obtained with rectangular and triangular single element mixer nozzles is presented. Equations are developed for estimating the peak axial velocity decay curves for a wide range of nozzle configurations.
Groesbeck, D. E.↗
BREAKUP OF LIQUID JETS BY TRANSVERSE SHOCKS
Multiple shock waves impinging on a single liquid jet and on two parallel jets in a direction perpendicular to their flow axes
SHOCK WAVE↗
Into Mesh Lubrication of Spur Gears with Arbitrary Offset Oil Jet. I: For Jet Velocity Less than or Equal to Gear Velocity
An analysis was conducted for into mesh oil jet lubrication with an arbitrary offset and inclination angle from the pitch point for the case where the oil jet velocity is equal to or less than pitch line velocity. The analysis includes the case for the oil jet offset from the pitch point in the direction of the pinion and where the oil jet is inclined to intersect the common pitch point. Equations were developed for the minimum oil jet velocity required to impinge on the pinion or gear and the optimum oil jet velocity to obtain the maximum impingement depth.
Akin, L. S.↗
Into mesh lubrication of spur gears with arbitrary offset oil jet. I - For jet velocity less than or equal to gear velocity
An analysis was conducted for into mesh oil jet lubrication with an arbitrary offset and inclination angle from the pitch point for the case where the oil jet velocity is equal to or less than pitch line velocity. The analysis includes the case for the oil jet offset from the pitch point in the direction of the pinion and where the oil jet is inclined to intersect the common pitch point. Equations were developed for the minimum oil jet velocity required to impinge on the pinion or gear and the optimum oil jet velocity to obtain the maximum impingement depth.
Akin, L. S.↗
On the Dynamic Characteristics of Free-Liquid Jets and a Partial Correlation with Orifice Geometry
A technique for evaluating the dynamic characteristics of free-liquid jets on a comparative basis is presented. This method consists of determining the pressure distribution produced by the perpendicular impingement of a jet upon a flat plate and using these data for comparing and categorizing jets with unknown properties in terms of similar data produced by jets having known characteristics-i.e., with jets produced by fully developed turbulent flow, fully developed laminar flow, and a jet having a near-uniform velocity profile. The visual characteristics, as well as both the mean and the fluctuating pressure distributions, are presented for these three reference configurations and for a number of jets produced by orifices having varying length-diameter ratios, combined with varying degrees of surface roughness in the initial five diameters of straight bore.
Rupe, Jack H.↗