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A one-eighth scale turbojet test cell was used to investigate the effects of various design parameters on augmentor performance. The augmentor inlet design, nozzle-to-augimentor spacing, engine flow rate, nozzle total temperature and pressure, an augmentor tube diameter were varied to determine what ef-ect they had on augmentation ratio, total'air pumped through the system, and pressure, temperature, and velocity distributions within the augmentor. In addition, two augmentor tubes were combined in tandem to investi tube gate the characteristics of a tertiary augmentor configuration., Naval Air Propulsion Center

Multiple-wavelength light transmission measurements were used to measure the mean particle size (d32), index of refraction (m) and standard deviation (o) of the small particles in the edge of the plume of a small solid propellant rocket motor. The results have shown that the multiple-wavelength light transmission measurement technique can be used to obtain these variables. The technique was shown to be more sensitive to changes in d32 and standard deviation (o) than to m. A GAP/AP/4.7 % aluminum propellant burned at 25 atm produced particles with d32 = 0.150 ± 0.006 n, o = 1.50 ± 0.04 and m = 1.63 ± 0.13. The good correlation of the data indicated that only submicron particles were present in the edge of the plume., http://archive.org/details/multiplewaveleng1094526645, Major, Korean Air Force, Approved for public release; distribution is unlimited.

Three propellants with aluminum/silicon weight percentages of 18/0%, 13.5/4.5%, and 12/6% were fired in a subscale motor to determine if the plume infrared signature could be reduced without a significant loss in specific impulse. Spectral measurements from 2.5 to 5.5 micrometers and thermal measurements from 3.5 to 5.0 micrometers were made. Plume particle size measurements showed that only particles with small diameters (less than 1.93 micrometers) were present with any significant volume. Replacing a portion of the aluminum in a highly metallized solid propellant with silicon was found to eliminate the Al2O3 in favor of SiO2 and Al6SiOl3, without any change in particulate mass concentration or any large change in particle size distribution. These particulates were found to have significantly lower absorptivity than Al2O3. An additional investigation was conducted to determine the particle size distribution at the nozzle entrance. Malvern ensemble scattering, phase-Doppler single particle scattering and laser transmittance measurements made through windows in the combustion chamber at the nozzle entrance indicated that large particles were present (to 250 micrometers). However, most of the mass of the particles was contained in particles with diameters smaller than 5 micrometers. Approximate calculations made with the measured data showed that if 100 micrometers particles are present with the smoke (particles with diameters less than 2 micrometers) they could account for only approximately 10% of the article volume, http://archive.org/details/investigationofe1094528309, Lieutenant Commander, United States Navy, Approved for public release; distribution is unlimited.

Characteristics of the products of combustion of metallized solid propellant strands at pressures between 250 and 750 psi were investigated using holography and light scattering measurements. In addition, scanning electron microscope and light scattering measurements were used to examine guenched residue. A reduced smoke ZrC propellant and three propellants of varying aluminum loading (2%, 4.8%, and 16%) were examined. The objective of the experiments was to provide sufficient particle data from strand burners to make it possible to determine if any correlation of results from this method of analysis could be made with results from other more complex solid propellant motor measurements, such as plume probe and signature measurements. The results of these efforts reflected the inability of any single technigue of analysis to completely describe particle size distributions. These results also suggest the need for modificaton of current experimental apparatus and procedures., http://archive.org/details/anexperimentalin1094527044, Captain, United States Army, Approved for public release; distribution is unlimited.

An investigation was conducted to determine the feasibility of a small, low-cost, caseless, hybrid-booster/solid-fuel ramjet (H/SFRJ) that utilizes a common fuel grain and has no ejectables. Performance of an air-to-ground missile with a solid propellant booster and SFRJ sustainer, capable of being fired from an unmanned aerial vehicle or helicopter was obtained using an Air Force computer code. A H/SFRJ motor was then designed analytically and compared to the generated computer output. The results showed that a H/SFRJ that has performance equal to a solid-booster SFRJ is feasible. The final missile design had a range of 20 nm, a flight Mach number of 2.0, a diameter and length of 5 and 99 inches respectively, and weighed 82 lb. Caseless hybrid rockets with erodible nozzles were tested to validate assumptions made in the design analysis. In addition, transition from hybrid-rocket booster to solid-fuel ramjet sustainer was demonstrated. (MM), http://archive.org/details/integralhybridbo1094526004, Lieutenant, United States Navy, Approved for public release; distribution is unlimited.

An apparatus was designed for use in determining ignition and combustion characteristics of metallic fuel particles and liquid fuel droplets. The design was tailored around the available data acquisition systems and diagnostic instruments. The apparatus consisted of a small windowed combustion bomb, a C02 laser for particle ignition, a thermal imaging camera for recording the ignition process, a helium-neon laser and a 1024 element linear diode array sampled at 1Mhz for measuring forward scattered light and determining particle size (Fraunhofer diffraction). All major components were individually utilized. However, equipment limitations prevented actual use of the system for measurement of the burning rates of particles. Recommendations are made which would permit the original objectives to be met, http://archive.org/details/anpparatusformea1094526882, Lieutenant, United States Navy, Approved for public release; distribution is unlimited.

An evaluation of five liquid-fueled pulse detonation engine combustor geometries and flow field conditions was performed over a wide range of equivalence ratios. Particle sizing and spray characterization of commercially available atomizers was conducted to determine the optimum conditions that produced acceptable mass flow and particle size distribution for use in the combustor. The chosen atomizer was installed in the combustor geometries and then analyzed over a range of combustor conditions to measure deflagration to detonation transition (DDT) distances and detonation wave velocities for each condition. Testing was conducted for ambient (100-110 deg F) and higher wall temperatures (>300 deg F) at an operating frequency of 5Hz. It was found that the shortest DDT for JP10 and O2 was achieved using a stepped front-end insert under hot conditions and with a loaded equivalence ratio greater than .75, but less than 1.15., http://archive.org/details/evaluationofliqu1094532628, N0001498WR20018, NA, U.S. Navy (U.S.N.) author., Approved for public release; distribution is unlimited.

An investigation was conducted to determine the feasibility of a low-cost, caseless, solid-fuel integral-rocket ramjet (IRSFRJ) that has no ejecta. Analytical design of a ramjet powered air-to-ground missile capable of being fired from a remotely piloted vehicle or helicopter was accomplished using current JANNAF and Air Force computer codes. The results showed that an IRSFRJ powered missile can exceed the velocity and range of current systems by more than a two to one ratio, without an increase in missile length and weight. A caseless IRSFRJ with a non-ejecting port cover was designed and tested. The experimental results of the static tests showed that a low-cost, caseless IRSFRJ with a nonejecting port cover is a viable design. Rocket-ramjet transition was demonstrated and ramjet ignition was found to be insensitive to the booster tail-off to air-injection timing sequence., http://archive.org/details/designndtestingo1094528115, Captain, United States Army, Approved for public release; distribution is unlimited.

Aluminum oxide(Al2O3) particles of known size distribution were cast into a solid propellant which burned at temperatures less than the melting point of Al2O3. Thus, particles of known size distribution existed at the nozzle inlet and in the plume. Malvern particle sizing instruments were used to make measurements at these two location using a windowed subscale motor and the results were compared to the known distribution. In the motor, measurements were limited due to disruptive flow from the window purge gas. However, the unaffected larger modes were properly measured. In the plume, the measurements of the modes were quite accurate, but low signal strength resulted in some inaccuracies for the mass contained in each mode. A phase Doppler particle analyzer was adapted to an existing plume probe. Initial measurements at two radial locations were in good agreement with the expected size distribution, http://archive.org/details/validationndimpl1094527329, Lieutenant, United States Navy, Approved for public release; distribution is unlimited.

An experimental investigation was conducted to measure soot properties and concentration, and infrared signature of the plume of a kerosene/gaseous oxygen rocket motor. Multiple-wavelength measurements were used to obtain soot parameters. It was found that the multiple-wavelength technique appeared to work well for obtaining soot properties and concentration. The results implied that the soot particulate was very porous for the most fuel-rich conditions and became more compact as the 0/F ratio increased, http://archive.org/details/sootparticlesize109458982, Major, Brazil Air Force, Approved for public release; distribution is unlimited.

http://archive.org/details/holographicparti1094523253

The research program involved the modification and use of an existing pulse detonation engine (PDE) to investigate the detonability of a JP-10/air aerosol. The detonation of a JP-10 aerosol in air proved more difficult than was originally anticipated. The use of a small JP- 10/oxygen pre-detonator to provide direct initiation results in a transition region with a geometric diffraction and compositional discontinuity. Propagation of a detonation into such a region is very complex but critical to the re-establishment of the detonation wave in the JP-10/air mixture. A high-speed camera was used to image the wave in the transition region and provide spatial information. High frequency pressure transducers were used along the combustor axis to determine wave speed. The ultimate goal was to determine the conditions required to ensure reliable re-establishment of a detonation wave in the JP-10/air aerosol mixture. Unfortunately, the confined planar JP-10/oxygen detonations in the pre-detonator were unable to transition into unconfined spherical detonation fronts in the JP- 10/air aerosol. Furthermore, the ratio of main combustor diameter to pre- detonator diameter was too large to allow re-initiation of detonation at the main combustor wall, http://archive.org/details/propagationoftwo109457772, Lieutenant, United States Navy, Approved for public release; distribution is unlimited.

An experimental investigation was conducted to determine if a new high speed IR microscope could be used to study the ignition and combustion characteristics of boron/boron carbide and to measure the particle emissivity as a function of temperature. Air heater limitations did not permit the investigation of ignition characteristics. Emissivity in the 2 - 5 fim band was measured as a function of temperature using a small boron filament. Data obtained using different IR band-pass filters resulted in significantly different results due to the apparent dependence of the emissivity of boron oxide on both temperature and wavelength. It was also found that care must be used to insure that the entire image is in sharp focus and that a means must be provided for measuring an accurate surface temperature., http://archive.org/details/irimagingforcomb1094523939, Lieutenant Commander, Republic of China Navy, Approved for public release; distribution is unlimited.

The NPS Tactical Horizon Extension Project objective is to define and demonstrate a concept by which task force-level commanders and below can obtain a persistent, over-the-horizon surveillance capability for the purpose of target development and other missions without tasking national or theater-level assets. Our goal is to increase the ISR capacity of units who normally would not rate the priority to task a Predator, Global Hawk, or U-2. There are two guiding tenets in developing this concept. First, the equipment and its control should be organic to the SOF unit or task force. Second, utilizing this capability should not require the soldier to carry any additional equipment into the field. Initial research led us to the idea of using networked unmanned aerial systems (UAS's) to generate an over-the-horizon surveillance capability for SOF. We demonstrated the concept by forming a network comprised of a forward ground team, an inexpensive, test-bed UAS equipped with an off-the-shelf video camera, a manned aircraft, and a tactical operations center (TOC). We attained connectivity through an ITT Mesh structure at 2.4 GHz, amplified to 1W. Researchers were from the Defense Analysis, Mechanical and Astronautical Engineering, and Information Sciences Departments. We conducted successful experiments through the USSOCOM-NPS Cooperative Field Experimentation Program., http://archive.org/details/extendingtactica109452582, Outstanding Thesis, Approved for public release; distribution is unlimited.

Naval Postgraduate School's (NPS) Tactical Network Topology (TNT) experiments seek to develop, implement and identify sensor-unmanned vehicle network, and network-centric operations to assist DoD warfighters in the Global War on Terrorism (GWOT). Using biometric data for rapid identification of High Value Targets (HVT) in ground and Maritiime Interdiction Operations (MIO) is critical to the emeging special operations concept. The goal is to explore solutions and operational constraints associated with biometric data analysis and rapid identification by means of adhoc self forming sensor unmanned vehicle (UV) wireless networks. The objectives of this thesis are to look at how biometrics has performed in a testbed environment that is simulating a real special operations environment in theatre. This thesis is meant to explore and explain the biometrics process that was conducted on top of the tactical network and evaluate its performance. This thesis provided the process model for biometrics identification in the tactical networks environment. This thesis also evaluated the length of time that it took to transmit the fingerprint data from the field to the ABIS databvase, with an identification result then sent back to the field. The longest time that was observed was 70 minutes (using low bandwidth Satellite communications), while the shortest time was 4 minutes for reachback to ABIS and 2 minutes for a local database., http://archive.org/details/performancendusa109452414, Approved for public release; distribution is unlimited.

Aluminized propellant strand lengths from one-quarter to two inches were burned at accelerations from zero to 1000g at a mean combustion pressure of 500 psia to study the effect of acceleration and strand length on burning rate augmentation. Propellant ammonium perchlorate oxidizer size and base burning rate were varied to investigate their effects. Each post-fire residue was photographically recorded and chemical analysis was performed by X-Ray powder diffraction., http://archive.org/details/aninvestigationo1094515049, Lieutenant Commander, United States Navy

The atomization of a gelled boron slurry fuel using two commercially available airblast atomizers was studied at atmospheric pressure in non-reacting flow. The atomization of water was also characterized for comparison. Each atomizer was operated at two different liquid mass flow rates and several air/ fuel ratios. Drop size distribution was measured using a Malvern 2600 HSD Laser Diffraction Particle Sizer, Drop sizes acceptable for use in ramjet combustors could be obtained for the gelled slurry fuel from both atomizers. However, this required air/fuel ratios too high for practical applications. It appears that secondary atomization methods or different types of atomizers will be required to obtain high ramjet combustion efficiencies with these fuels if they are to be used over typical ramjet operating envelopes., http://archive.org/details/atomizationofjpb1094523549, Lieutenant, United States Navy

The optical properties of motor aluminum oxide are required inputs to current plume signature prediction codes, such as SIRRM. Accurate predictions are possible only if variations in the particle emissivity due to changes in particle size, contamination, and changing temperature, etc. , are known . This investigation demonstrated a simplified method for determination of the emissivity of rocket motor generated alumina. Plume particulate material was collected on tungsten alloy wire during motor firings. A DC circuit was used to resistively heat the material, and the temperature was determined at various points by relating the wire resistivity to circuit current and voltage. An Agema Thermovision infrared (3.5-5 (j.) camera and microscope were used to observe the material during heating, and broad-band emissivity was computed using system software. It was estimated that the emissivity could be measured with an accuracy of ± 3%. Motor alumina was found to have significantly greater emissivity than pure alumina in the temperature range of 500-1200K., http://archive.org/details/emissivityofrock1094523876, Lieutenant, United States Navy, Approved for public release; distribution is unlimited.

Three test programs were conducted to provide thepreliminary groundwork for thedesign of a small turbojet engine from turbocharger rotorcomponents for possible Uninhabited Aerial Vehicle applications. The first program involved the performance mapping of the Garrett T2 turbocharger centrifugal compressor. The second program involved the bench testing of a small turbojet engine, the Sophia J450, at 115000 RPM, and comparing the results to another small turbojet, the JPX-240, from previously documented research. The compressor radii of the two engines were identical but greater than that of the Garrett compressor. The two engines, despite their physical similarities, had different fuel requirements. The J450 used heavy fuel (fuel pump required) while the JPX used liquid propane (pressurized fuel tank required). The third program involved the performance prediction of the J450 using GASTURB cycle analysis software. The compressor map generated from the Garrett T2 test was imported into GASTURB and used to predict the J450 performance at 94000,105000,115000, and 123000 RPM. The performance predictions agreed reasonably well with actual J450 performance, http://archive.org/details/turbochargerstos109459094, Lieutenant, United States Navy, Approved for public release; distribution is unlimited.

Double base rocket propellants with and without aluminum were burned in a centrifuge at two pressures and nine accelerations. ,The burning rates were measured to isolate the effect of the aluminum. The burning rate of the non-aluminized propellant was found to vary with acceleration and a model was advanced. The addition of aluminum causes an increase in burning rate at higher accelerations and a possible mechanism is discussed., http://archive.org/details/theeffectofaccel1094524678, Lieutenant (j.g.), United States Navy

Many military Intelligence Surveillance and Reconnaissance (ISR) operations would benefit greatly from a fleet of disparate sensor-bearing UAVs that are tightly integrated via a communications network, work cooperatively for a common operational objective, enhance situation awareness of the areas of operation, and increase persistence of sensor dwell time on strategic targets. This would enable continuity in the entire target acquisition cycle, from detection to classification to identification and finally localization of targets, in a diverse and dynamic environment. The integration of sensors and development of tactics in a cooperative sensing environment is one of the current focuses among the military intelligence community, and hence motivates this thesis effort. By building models with an existing agent-based simulation platform and using an extremely efficient experimental design methodology, numerous factors which could potentially affect the effectiveness of a cooperative sensing network against two arrays of targets are explored. The factors considered include UAV airspeed, reliability, detection/classification coverage and probability, network latency and degradation, UAV configurations and responsiveness, as well as air space separation. The two arrays of targets are mobile armor concentrations and time critical targets, these vary in their deployment profiles, vulnerability constraints and ease of detectability. Factors characterizing these targets, such as the shoot-and-scoot behavior of time critical targets, are also investigated. The study provides operational insights pertaining to the design and effective use of cooperative sensing for ISR purposes. These include the importance of having good UAV sensor capabilities, the need for a suite of sensors to aid in locating well-camouflaged time-critical targets, and the need for "intelligent" application of UAV cooperation tactics based on the characteristics of recently-classified targets., http://archive.org/details/theuseofgentbase109451740, Approved for public release; distribution is unlimited.

The NPS Tactical Horizon Extension Project objective is to define and demonstrate a concept by which task force-level commanders and below can obtain a persistent, over-the-horizon surveillance capability for the purpose of target development and other missions without tasking national or theater-level assets. Our goal is to increase the ISR capacity of units who normally would not rate the priority to task a Predator, Global Hawk, or U-2. There are two guiding tenets in developing this concept. First, the equipment and its control should be organic to the SOF unit or task force. Second, utilizing this capability should not require the soldier to carry any additional equipment into the field. Initial research led us to the idea of using networked unmanned aerial systems (UAS's) to generate an over-the-horizon surveillance capability for SOF. We demonstrated the concept by forming a network comprised of a forward ground team, an inexpensive, test-bed UAS equipped with an off-the-shelf video camera, a manned aircraft, and a tactical operations center (TOC). We attained connectivity through an ITT Mesh structure at 2.4 GHz, amplified to 1W. Researchers were from the Defense Analysis, Mechanical and Astronautical Engineering, and Information Sciences Departments. We conducted successful experiments through the USSOCOM-NPS Cooperative Field Experimentation Program.

Many military Intelligence Surveillance and Reconnaissance (ISR) operations would benefit greatly from a fleet of disparate sensor-bearing UAVs that are tightly integrated via a communications network, work cooperatively for a common operational objective, enhance situation awareness of the areas of operation, and increase persistence of sensor dwell time on strategic targets. This would enable continuity in the entire target acquisition cycle, from detection to classification to identification and finally localization of targets, in a diverse and dynamic environment. The integration of sensors and development of tactics in a cooperative sensing environment is one of the current focuses among the military intelligence community, and hence motivates this thesis effort. By building models with an existing agent-based simulation platform and using an extremely efficient experimental design methodology, numerous factors which could potentially affect the effectiveness of a cooperative sensing network against two arrays of targets are explored. The factors considered include UAV airspeed, reliability, detection/classification coverage and probability, network latency and degradation, UAV configurations and responsiveness, as well as air space separation. The two arrays of targets are mobile armor concentrations and time critical targets, these vary in their deployment profiles, vulnerability constraints and ease of detectability. Factors characterizing these targets, such as the shoot-and-scoot behavior of time critical targets, are also investigated. The study provides operational insights pertaining to the design and effective use of cooperative sensing for ISR purposes. These include the importance of having good UAV sensor capabilities, the need for a suite of sensors to aid in locating well-camouflaged time-critical targets, and the need for "intelligent" application of UAV cooperation tactics based on the characteristics of recently-classified targets.

Twenty two papers on fundamentals of high-speed deflagrations and detonations written by international experts are assembled in this volume. The papers have been presented at the International Colloquium on Control of Detonation Processes held in Moscow, Russia on July 4-7, 2000. Various aspects of deflagration to detonation transition as well as direct detonation initiation in gaseous and heterogeneous media are discussed with the emphasis on control of the predetonation distance and parameters of transient high-speed combustion regimes. Applications of various explosion control techniques to pulsed detonation engines (PDE) are described., Original contains color plates: All DTIC reproductions will be in black and white.

Twenty two papers on fundamentals of high-speed deflagrations and detonations written by international experts are assembled in this volume. The papers have been presented at the International Colloquium on Control of Detonation Processes held in Moscow, Russia on July 4-7, 2000. Various aspects of deflagration to detonation transition as well as direct detonation initiation in gaseous and heterogeneous media are discussed with the emphasis on control of the predetonation distance and parameters of transient high-speed combustion regimes. Applications of various explosion control techniques to pulsed detonation engines (PDE) are described.

The research program involved the modification and use of an existing pulse detonation engine (PDE) to investigate the detonability of a JP-10/air aerosol. The detonation of a JP-10 aerosol in air proved more difficult than was originally anticipated. The use of a small JP- 10/oxygen pre-detonator to provide direct initiation results in a transition region with a geometric diffraction and compositional discontinuity. Propagation of a detonation into such a region is very complex but critical to the re-establishment of the detonation wave in the JP-10/air mixture. A high-speed camera was used to image the wave in the transition region and provide spatial information. High frequency pressure transducers were used along the combustor axis to determine wave speed. The ultimate goal was to determine the conditions required to ensure reliable re-establishment of a detonation wave in the JP-10/air aerosol mixture. Unfortunately, the confined planar JP-10/oxygen detonations in the pre-detonator were unable to transition into unconfined spherical detonation fronts in the JP- 10/air aerosol. Furthermore, the ratio of main combustor diameter to pre- detonator diameter was too large to allow re-initiation of detonation at the main combustor wall

An evaluation of five liquid-fueled pulse detonation engine combustor geometries and flow field conditions was performed over a wide range of equivalence ratios. Particle sizing and spray characterization of commercially available atomizers was conducted to determine the optimum conditions that produced acceptable mass flow and particle size distribution for use in the combustor. The chosen atomizer was installed in the combustor geometries and then analyzed over a range of combustor conditions to measure deflagration to detonation transition (DDT) distances and detonation wave velocities for each condition. Testing was conducted for ambient (100-110 deg F) and higher wall temperatures (>300 deg F) at an operating frequency of 5Hz. It was found that the shortest DDT for JP10 and O2 was achieved using a stepped front-end insert under hot conditions and with a loaded equivalence ratio greater than .75, but less than 1.15.

An experimental investigation was conducted to measure soot properties and concentration, and infrared signature of the plume of a kerosene/gaseous oxygen rocket motor. Multiple-wavelength measurements were used to obtain soot parameters. It was found that the multiple-wavelength technique appeared to work well for obtaining soot properties and concentration. The results implied that the soot particulate was very porous for the most fuel-rich conditions and became more compact as the 0/F ratio increased

Three test programs were conducted to provide thepreliminary groundwork for thedesign of a small turbojet engine from turbocharger rotorcomponents for possible Uninhabited Aerial Vehicle applications. The first program involved the performance mapping of the Garrett T2 turbocharger centrifugal compressor. The second program involved the bench testing of a small turbojet engine, the Sophia J450, at 115000 RPM, and comparing the results to another small turbojet, the JPX-240, from previously documented research. The compressor radii of the two engines were identical but greater than that of the Garrett compressor. The two engines, despite their physical similarities, had different fuel requirements. The J450 used heavy fuel (fuel pump required) while the JPX used liquid propane (pressurized fuel tank required). The third program involved the performance prediction of the J450 using GASTURB cycle analysis software. The compressor map generated from the Garrett T2 test was imported into GASTURB and used to predict the J450 performance at 94000,105000,115000, and 123000 RPM. The performance predictions agreed reasonably well with actual J450 performance

An experimental investigation was conducted in which the burning characteristics of individual aluminum/aluminum oxide particles were measured using a windowed combustion bomb at atmospheric pressure and under gravity-fall conditions. A scanning electron microscope (SEM) was used to measure the size distribution of the initial aluminum particles and the aluminum oxide residue. Analysis of the residue indicated that the mass of aluminum oxide contained in particles larger than 12 microns was less than 25 percent, in good agreement with data reported from aluminized solid propellant. The measured particle size distributions and photomicrographs implied that the burning aluminum particles periodically expel aluminum oxide fragments with sizes between 14 and 36 microns.

The measurement of soot particulates densities in gas turbine engine and rocket exhausts is an area of continuing scientific investigation. Knowledge of exhaust plume soot concentration and sizing is critical for plume signature determination, currently a focus of theatre ballistic missile defense research. This thesis research investigates the development and initial calibration of an instrument that will determine soot particle densities in an exhaust plume, by measuring the absorbtion of a light beam transmitted through the plume. This instrument utilizes an argon ion laser, four passes through the exhaust plume, and a phase conjugate crystal to correct for aberrations in the transmitted beam. Several aspects of instrument layout and performance were investigated, and an initial calibration against a conventional probe sampling technique was performed, using an ethelyne air combustor as a soot source. While soot concentration measurements obtained with the instrument were internally consistent, the primitive sample probe used limited the opportunity to do an accurate comparison against a conventional method. The method requires further development, but shows significant promise for use in a jet engine test cell.

An experimental investigation to measure particle size distributions in the plume of sub-scale solid rocket motors was conducted. A phase-Doppler particle analyzer (pDPA) in conjunction with three-wavelength extinction measurements were used in a specially designed particle collection probe in an attempt to determine the entire plume particle size distribution. In addition, a laser ensemble particle sizer was used for comparative data. The PDPA and Malvem distributions agreed in the observed modes near 1 and 4.5 mm diameter (d). Scanning Electron Microscope (SEM) pictures of collected particles were in good agreement with the measured Malvem Sauter Mean diameter (d,%) of 2.59 mm. Data analysis indicate that less than 3% of the total mass of the particles was contained in particles with diameter d <0.5 mm. Therefore, the PDPA, which can typically measure particles down to a minimum diameter of 0.5 mm with a dynamic range (d max:d min) of 50:1, can be used by itself to determine the particle size distribution. Multiple wavelength measurements were found to be very sensitive to inaccuracies in the measured transmittances.

An investigation was conducted to determine the feasibility of a small, low-cost, caseless, hybrid-booster/solid-fuel ramjet (H/SFRJ) that utilizes a common fuel grain and has no ejectables. Performance of an air-to-ground missile with a solid propellant booster and SFRJ sustainer, capable of being fired from an unmanned aerial vehicle or helicopter was obtained using an Air Force computer code. A H/SFRJ motor was then designed analytically and compared to the generated computer output. The results showed that a H/SFRJ that has performance equal to a solid-booster SFRJ is feasible. The final missile design had a range of 20 nm, a flight Mach number of 2.0, a diameter and length of 5 and 99 inches respectively, and weighed 82 lb. Caseless hybrid rockets with erodible nozzles were tested to validate assumptions made in the design analysis. In addition, transition from hybrid-rocket booster to solid-fuel ramjet sustainer was demonstrated. (MM)

An investigation was conducted to experimentally quantify the interaction of particulates with the fuel-rich plume flowfield typical for solid propellant rocket motors. This was done in order to optimize enhanced mixing devices or chemical-additive addition for afterburning suppression. Laser sheet flow visualization, sound spectra measurements, plume thermal images and particle size distribution measurements were utilized with reacting and non- reacting gaseous plumes and with the plumes from highly aluminized propellant and minimum smoke propellant. Several devices were evaluated for their effectiveness in providing increased mixing in the supersonic shear layer. It was found that the generation of axial vortices in the supersonic shear layers at the nozzle exit of rocket motors operating with characteristically high exit Mach numbers and high temperatures can enhance the mixing rates and affect the afterburning. The presence of large quantities of particulates both in the shear layer and in the plume core appears to significantly change the results obtained using enhanced mixing devices. Initial results with a ramp nozzle indicate that enhanced large-scale mixing can be provided in the presence of high particulate loadings in the plume.

A dual, axially-in-line, side-dump, liquid-fueled ramjet combustor was designed and tested with varying fuel-air ratios, atomizer types, and air distributions between the two inlets. Particle size distributions produced by the atomizers were measured at the inlet duct plane. When operated in a contra- flow direction, all of the atomizers produced excellent atomization with a Sauter mean diameter less than 14 microns. The dual, in-line inlets provided improved flammability limits and combustion efficiencies at lean fuel-air ratios when compared to single side-dump performance. Direct injection of approximately 20% of the fuel flow into the dome region was found to provide improved lean flammability limits for the single side-dump, but was not required with the dual inlets. The fuel distribution in the inlet duct required for good flammability limits and combustion efficiency was opposite to that required to prevent pressure oscillations, indicating that a dump plane aero-grid will often be necessary. A dump angle of 45 deg resulted in lower than desired combustion efficiencies, apparently due to poor mixing with the air from the aft inlet.

Three propellants with aluminum/silicon weight percentages of 18/0%, 13.5/4.5%, and 12/6% were fired in a subscale motor to determine if the plume infrared signature could be reduced without a significant loss in specific impulse. Spectral measurements from 2.5 to 5.5 micrometers and thermal measurements from 3.5 to 5.0 micrometers were made. Plume particle size measurements showed that only particles with small diameters (less than 1.93 micrometers) were present with any significant volume. Replacing a portion of the aluminum in a highly metallized solid propellant with silicon was found to eliminate the Al2O3 in favor of SiO2 and Al6SiOl3, without any change in particulate mass concentration or any large change in particle size distribution. These particulates were found to have significantly lower absorptivity than Al2O3. An additional investigation was conducted to determine the particle size distribution at the nozzle entrance. Malvern ensemble scattering, phase-Doppler single particle scattering and laser transmittance measurements made through windows in the combustion chamber at the nozzle entrance indicated that large particles were present (to 250 micrometers). However, most of the mass of the particles was contained in particles with diameters smaller than 5 micrometers. Approximate calculations made with the measured data showed that if 100 micrometers particles are present with the smoke (particles with diameters less than 2 micrometers) they could account for only approximately 10% of the article volume

A dual, axially-in-line, side-dump, liquid-fueled ramjet combustor was designed and tested with varying fuel-air ratios, atomizer types, and air distributions between the two inlets. Particle size distributions produced by the atomizers were measured at the inlet duct plane. When operated in a contra- flow direction, all of the atomizers produced excellent atomization with a Sauter mean diameter less than 14 microns. The dual, in-line inlets provided improved flammability limits and combustion efficiencies at lean fuel-air ratios when compared to single side-dump performance. Direct injection of approximately 20% of the fuel flow into the dome region was found to provide improved lean flammability limits for the single side-dump, but was not required with the dual inlets. The fuel distribution in the inlet duct required for good flammability limits and combustion efficiency was opposite to that required to prevent pressure oscillations, indicating that a dump plane aero-grid will often be necessary. A dump angle of 45 deg resulted in lower than desired combustion efficiencies, apparently due to poor mixing with the air from the aft inlet.

Methods of measuring soot particle densities have been of interest for several decades. Plume signature determination of both rocket and air-breathing engines is of concern when applied to pollution and theater missile ballistic defense strategies. Application of non-intrusive traditional techniques employing Bouguer's law relied on Sauter mean diameter, statistical deviation and the probability density function in order to compensate for the ambiguities present in the extension of classical Mie theory. Our investigation developed an apparatus which will determine soot particle densities by measuring extinction from absorption of light energy transmitted through an exhaust plume. The method used was a two-pass technique using an optical phase conjugator (OPC) which returned the non-absorbed portion of light energy. When the apparatus was used with a retroreflector, it produced accurate results but did not compensate for thermal blooming or beam steering. Characteristics of a photorefractive crystal used in the OPC process allowed for the return of an incident beam corrected for aberrations. Although the OPC returned the phase conjugate of the incident beam its size precluded the return of all of the transmitted data because data was lost on the blossomed beam.

An apparatus was designed for use in determining ignition and combustion characteristics of metallic fuel particles and liquid fuel droplets. The design was tailored around the available data acquisition systems and diagnostic instruments. The apparatus consisted of a small windowed combustion bomb, a C02 laser for particle ignition, a thermal imaging camera for recording the ignition process, a helium-neon laser and a 1024 element linear diode array sampled at 1Mhz for measuring forward scattered light and determining particle size (Fraunhofer diffraction). All major components were individually utilized. However, equipment limitations prevented actual use of the system for measurement of the burning rates of particles. Recommendations are made which would permit the original objectives to be met

Aluminum oxide(Al2O3) particles of known size distribution were cast into a solid propellant which burned at temperatures less than the melting point of Al2O3. Thus, particles of known size distribution existed at the nozzle inlet and in the plume. Malvern particle sizing instruments were used to make measurements at these two location using a windowed subscale motor and the results were compared to the known distribution. In the motor, measurements were limited due to disruptive flow from the window purge gas. However, the unaffected larger modes were properly measured. In the plume, the measurements of the modes were quite accurate, but low signal strength resulted in some inaccuracies for the mass contained in each mode. A phase Doppler particle analyzer was adapted to an existing plume probe. Initial measurements at two radial locations were in good agreement with the expected size distribution

The optical properties of motor aluminum oxide are required inputs to current plume signature prediction codes, such as SIRRM. Accurate predictions are possible only if variations in the particle emissivity due to changes in particle size, contamination, and changing temperature, etc. , are known . This investigation demonstrated a simplified method for determination of the emissivity of rocket motor generated alumina. Plume particulate material was collected on tungsten alloy wire during motor firings. A DC circuit was used to resistively heat the material, and the temperature was determined at various points by relating the wire resistivity to circuit current and voltage. An Agema Thermovision infrared (3.5-5 (j.) camera and microscope were used to observe the material during heating, and broad-band emissivity was computed using system software. It was estimated that the emissivity could be measured with an accuracy of ± 3%. Motor alumina was found to have significantly greater emissivity than pure alumina in the temperature range of 500-1200K.

The particle size distribution inside the combustion chamber and the changes that occurred across the exhaust nozzle were measured in a subscale solid propellant rocket motor with a 2% aluminized end-burning propellant grain and a highly underexpanded nozzle. A combination of diagnostic techniques were used. Size distributions in the exhaust plume were determined by a Single Particle Counter, a Malvern 2600 ensemble particle sizer, and by Scanning Electron Microscope (SEM) examinations of particles collected on a timed exposure impact probe. Size distributions inside the combustion chamber were determined by Malvern 2600 measurements through windows at the nozzle entrance, SEM examinations of particles collected from the nozzle entrance wall, and exhaust plume measurements of a helium quenched motor. It was determined that agglomeration processes dominated in the flow from the center of the combustion chamber up to the nozzle entrance. Particle breakup processes dominated particle behavior from the nozzle entrance, through the nozzle, and into the exhaust.

An experimental investigation was conducted to determine if a new high speed IR microscope could be used to study the ignition and combustion characteristics of boron/boron carbide and to measure the particle emissivity as a function of temperature. Air heater limitations did not permit the investigation of ignition characteristics. Emissivity in the 2 - 5 fim band was measured as a function of temperature using a small boron filament. Data obtained using different IR band-pass filters resulted in significantly different results due to the apparent dependence of the emissivity of boron oxide on both temperature and wavelength. It was also found that care must be used to insure that the entire image is in sharp focus and that a means must be provided for measuring an accurate surface temperature.

The atomization of a gelled boron slurry fuel using two commercially available airblast atomizers was studied at atmospheric pressure in non-reacting flow. The atomization of water was also characterized for comparison. Each atomizer was operated at two different liquid mass flow rates and several air/ fuel ratios. Drop size distribution was measured using a Malvern 2600 HSD Laser Diffraction Particle Sizer, Drop sizes acceptable for use in ramjet combustors could be obtained for the gelled slurry fuel from both atomizers. However, this required air/fuel ratios too high for practical applications. It appears that secondary atomization methods or different types of atomizers will be required to obtain high ramjet combustion efficiencies with these fuels if they are to be used over typical ramjet operating envelopes.

The objective of the thesis was to determine the effects of equivalence ratio (Ø) and fuel composition on the infrared signature of solid fueled ramjets (SFRJ). Solid fuels investigated were Plexiglas, HTPB, and HTPB with aluminum, silicon, boron carbide, and/or magnesium. They were tested at chamber pressures of 80-170 psia and with equivalence ratios between 0.3 and 1.4. With the plume emissivity set to 1.0, plume irradiance was found to increase approximately with the second power of the actual combustor stagnation temperature. In addition to providing needed plume signature data for the SFRJ, this information can be used to validate numerical predictions from the SPF (Standardized Plume Flowfield) and SIRRM (Standardized Infrared Radiation Model) computer codes, which are used to predict the plume infrared signature.

Multiple-wavelength light transmission measurements were used to measure the mean particle size (d32), index of refraction (m) and standard deviation (o) of the small particles in the edge of the plume of a small solid propellant rocket motor. The results have shown that the multiple-wavelength light transmission measurement technique can be used to obtain these variables. The technique was shown to be more sensitive to changes in d32 and standard deviation (o) than to m. A GAP/AP/4.7 % aluminum propellant burned at 25 atm produced particles with d32 = 0.150 ± 0.006 n, o = 1.50 ± 0.04 and m = 1.63 ± 0.13. The good correlation of the data indicated that only submicron particles were present in the edge of the plume.

Accurate measurement of particle size distribution of rocket motor exhaust is essential for predicting the combustion efficiency and infrared plume signature. This thesis presents an automated method for extracting particle size distribution from scanning electron microscope (SEM) images. The SEM images were taken off a filter paper placed the end of a collection probe inserted into the exhaust plume. The automated SEM extraction system consists of an IBM AT-based computer system fitted with a 512 x 480 pixel frame grabber. Photographic images taken off the SEM are acquired via a vidicon camera. A C language program was written to control the hardware and automate the extraction process. A threshold is first applied to the digitized image and the resulting binary image is subjected to object segmentation. Each object is then sized and the distribution from one or more images can be plotted. The main bulk of this thesis is to document the software specially written to undertake this set of tasks. Results obtained were compared with that from a Malvern MasterSizer particle sizer and found to be favorable. Particles as small as 1/8 um have been successfully sized.

An investigation was conducted to determine the feasibility of a low-cost, caseless, solid-fuel integral-rocket ramjet (IRSFRJ) that has no ejecta. Analytical design of a ramjet powered air-to-ground missile capable of being fired from a remotely piloted vehicle or helicopter was accomplished using current JANNAF and Air Force computer codes. The results showed that an IRSFRJ powered missile can exceed the velocity and range of current systems by more than a two to one ratio, without an increase in missile length and weight. A caseless IRSFRJ with a non-ejecting port cover was designed and tested. The experimental results of the static tests showed that a low-cost, caseless IRSFRJ with a nonejecting port cover is a viable design. Rocket-ramjet transition was demonstrated and ramjet ignition was found to be insensitive to the booster tail-off to air-injection timing sequence.

A combined optical and collection particle sizing probe was further developed and utilized for in situ measurements in the exhaust plumes of solid propellant rocket motors. Probe shock-swallowing capabilities were verified using Schlieren observations under restricted motor operating conditions. Particle size number distributions obtained optically using a Malvern Mastersizer and from an automated data retrieval system for scanning electron microscope photographs of collected particles were in good agreement when referenced to common measurement limits. Most of the particles were smaller than 0.5 u but a significant number were present with diameters 19 10 u. A very few particles large than 15 u were also present, some as single particles and some as agglomerates. SEM results showed that many particles were smaller than 0.2 u outside the range of the Malvern instrument. Suggestions are made for further improvements and validation procedures for the probe.