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An experimental study of the exhaust plume of an aged (200,000 pulses), 0.44 N (0.1 lbf), hydrazine monopropellants thruster was performed with the goal of characterizing both the gas dynamic and contamination properties of the vacuum plume expansion. The thruster was operated in a high vacuum chamber over a thrust range from 0.44 to 1.10 N (0.1 to .25 lbf) with a nominal 0.14- sec-on/9.86-sec-off duty cycle using initial catalyst bed (Shell 405) temperatures of 367 K (200F), 478 K (400F), and 589 K (699F). Exhaust plume diagnostic systems employed included a mass spectrometer probe, a quartz crystal microbalance (QCM), a laser-Raman/Rayleigh scattering system, an electron beam fluorescence system, and a particle collection network. These systems determined plume species number densities and temperature, mass deposition rates, and the level of particulates in the plume; they also permitted visualization of the plume. Traditional engine performance parameters were also determined in order to relate performance and exhaust plume properties., Prepared in cooperation with ARO, Inc., Tullahoma, TN.

An experimental study of the condensation of gases in expansion flow fields was conducted under the auspices of the AFRPL CONSET Program. Pure gas expansions, as well as binary and ternary gas mixture expansions and the plume of a monopropellant hydrazine thruster were studied. Laser-Rayleigh and laser-Raman scattering, mass spectrometric sampling, and electron beam fluorescence were used as nonperturbing flow diagnostics. This report summarizes results of these experiments., Prepared in cooperation with ARO, Inc., Tullahoma, TN.

Laser-Raman scattering has been used to measure temperature and nitrogen number density in the combustion cylinder of a specialized research CI engine. Measurements were made as a function of crank angle degrees (CAD) for unfueled operation at 500 and 1,000 rpm and for operation at 1,000 rpm using n- heptane as an alternate fuel to diesel fuel no. 2. A pulsed ruby laser system was the excitation source for the Raman scattering, and the CAD resolution of the measurements was .0015 to 0.36 degrees., Prepared in cooperation with ARO, Inc., Tullahoma, TN.

An experimental study of the exhaust plume of a 0.44-N (0.1-1bf), hydrazine monopropellant thruster with a refurbished catalyst bed has been performed to characterize both the gas-dynamic and contamination properties of the vacuum plume expansion. The thruster was operated in a high-vacuum chamber over a thrust range of 0.44 to 1.10 N (0.1 to 0.25 bf) with a nominal 0.14- secon/9.86-sec-off duty cycle using initial catalyst bed temperatures of 367 and 478 K (200 and 400 F. The exhaust plume diagnostic systems employed included a mass spectrometer probe, a quartz crystal microbalance (QCM), and a laser Raman/ Rayleigh scattering system. These systems determined plume species number densities and temperatures, mass deposition rates, and the level of particulates in the plume. Traditional engine performance parameters were also determined in order to relate performance and exhaust plume properties., Prepared in cooperation with ARO, Inc., Tullahoma, TN.

Hypersonic N2 flow fields were produced using a conical nozzle of 1. 04-mm throat diameter and an exit plane area ratio of 13.4. The reservoir pressure was varied over the range of from 1.87 to 13.6 atm at the reservoir temperature of 285 K, and the reservoir conditions were such that both isentropic and anisentropic conditions existed within the axial region investigated. Axial and radial profiles of N2 number density and rotational temperature were measured using laser Raman scattering, and comparisons are presented with the method of characteristics isentropic prediction. The onset of condensation and subsequent cluster growth were observed using laser Rayleigh scattering and depolarization measurements as well as photographic recording. The Rayleigh and Raman scattering data were used to obtain estimates of the axial variation of the cluster size as well as the variation of the depolarization ratio with the mean number of molecules of the cluster., Prepared in cooperation with ARO, Inc., Tullahoma, TN. Rept. no. ARO-VKF-TR-74-77.

The feasibility of performing laser-Raman/Rayleigh scattering measurements in subsonic flows was demonstrated in the 6-in. Acoustic Research Tunnel (ART) of the Propulsion Wind Tunnel facility at AEDC. The ART is an open-circuit, atmospheric inbleed tunnel that operates on the Plenum Evacuation System of the 16-ft transonic Propulsion Wind Tunnel (16T). Laser-Raman/Rayleigh scattering techniques were used to measure air number density, H2O number density, and static temperature and to detect the onset of water vapor condensation. Measurements were made near the tunnel axial centerline over the Mach number range from 0.10 to 0.80. Measurements were also made in the turbulent boundary layer on the wall of the test section at Mach numbers 0.50 to 0.80. (Author), Prepared in cooperation with ARO, Inc., Tullahoma, TN.

Laser-Raman diagnostics have been used to determine the temporal variation of N2 and CO number densities in the muzzle blast region of a 20-mm Vulcan cannon. The measurements were made within 3.18 to 13.0 mm of the muzzle exit plane on the cannon axial centerline. Propellant WC-870 was used, and the rounds were downloaded to give a muzzle exit velocity of approximately 470 m/sec. A standard 98-gram projectile was launched. (Author), Prepared in cooperation with ARO, Inc., Tullahoma, TN.

Laser-Raman scattering has been utilized to discover nonequilibrium N2 vibrational levels in a continuous, resistance-heated wind tunnel (Tunnel C) and in an arc-heated wind tunnel (Tunnel F). Vibrational temperatures of up to two times the bulk reservoir temperature have been measured in the Tunnel F free stream. A double-diaphragm device for delay of the Tunnel F nozzle expansion was found to significantly reduce the vibrational temperature level. In tunnel C, the vibrational temperatures were found to be dependent upon the water vapor concentration in the flow. It is hypothesized that water vapor-induced de-excitation of the vibrationally excited nitrogen molecules results in a significant rise in local static temperature and corresponding reduction in Mach number. (Author), Prepared in cooperation with ARO, Inc., Tullahoma, TN.

The laser-Raman diagnostic technique has been used for investigating a ducted, two-stream, subsonic, H2/air combustion flow with turbulent jet mixing and recirculation. A primary jet of high-velocity air was surrounded by an outer, low-velocity hydrogen stream. The duct-to-inner-nozzle diameter ratio was varied. The ratios were 2 and 10 for the two conditions investigated. The radial distributions of static temperature and species number densities were determined at several axial positions for each test condition. (Author), Prepared in cooperation with ARO, Inc., Tullahoma, TN.

A study of the condensation of gases in expansion flow fields has been performed using laser Rayleigh scattering with the goal of determining the dependence of the spatial location of onset and subsequent condensate growth with gas reservoir conditions, gas source parameters, and gaseous species. Sonic orifice and conical nozzle expansions of N2 were studied for the range of reservoir pressure values from 0.26 to 10.2 atm at a nominal reservoir temperature of 285K. The conical nozzle expansions included the nozzle half angles of 5.60, 9.0, and 14.5 deg. Finally, sonic orifice expansions produced by sources of two different diameters were investigated for flow fields of Ar, N2, O2, and CO., Prepared in cooperation with ARO, Inc., Tullahoma, Tenn. Rept. no. ARO-VKF-TR-76-16.

After successful laboratory measurements of the rotational temperature T(R) of N2, O2, CO, and CO2 at atmospheric pressure and room temperature and of N2 at 296, 215, and 163 K at an equivalent room temperature pressure of 10 torr, measurements of the rotational temperature of these gases were made in the hypersonic flow field produced by either a sonic orifice or a conical nozzle expansion. Radial profile measurements of T(R) were performed at two axial positions for the N2 nozzle flow field at a reservoir pressure of 10 atm. Agreement was obtained with the electron beam results of Beylich using appropriate reservoir scaling laws. The axial variation of N2 number density was determined for the nozzle source over a range of reservoir pressures (3.3 to 10 atm), and radial profiles at two axial locations were determined for the 10-atm condition. Agreement with the MOC calculations was excellent., Prepared in cooperation with ARO, Inc., Arnold Air Force Station, Tenn. Rept. no. ARO-VKF-TR-74-93.

With escalating aerospace ground testing costs, it has become imperative to reduce test duration and yet maintain the quantity and quality of test data. because many of the non-perturbing flow diagnostic techniques developed at AEDC require a measurement of either induced or spontaneous emitted radiation, data acquisition time can be reduced if the spatial, spectral, and temporal variations of the radiation can be measured simultaneously. To achieve this reduction in data acquisition time, AEDC personnel have developed two multichannel radiation detection systems. The details of these two systems and an assessment of their capabilities are presented, and recommendations for improvements are made. (Author), Prepared in cooperation with Calspan Field Services, Inc., Arnold AFS, TN. AEDC Div.

Sonic orifice expansions of CO2 were investigated using laser Rayleigh scattering for detection of condensation onset within the expansion flow field. The axial region studied was 0.8 to 60 orifice diameters downstream of the orifice, and a range of reservoir pressures was employed for expansions of CO2 at ambient temperature. Two sonic orifice sources, 1.325- and 3.2-mm diameter, were studied for the purpose of determining the appropriate reservoir scaling laws for condensation onset and growth. Rayleigh scattering intensities are presented as a function of axial distance and reservoir pressure, and the results clearly show the regions of condensation onset and growth., Prepared in cooperation with ARO, Inc., Tullahoma, Tenn. Rept. no. ARO-VKF-TR-75-104.

Homogeneous condensation of argon was observed using sonic orifice expansion flow fields. The room temperature argon was studied over the range of reservoir pressures from 200 to 750 torr using a 3.2-mm orifice diameter. Condensation onset and the subsequent cluster growth was observed using laser Rayleigh scattering, and maximum supersaturation ratios as a function of reservoir pressures were determined. Depolarization ratio measurements were performed for the 750-torr expansion, and shape changes of the cluster were observed throughout the growth region. Comparisons of these results and previous mass spectrometric data are made, and specifically the mass fraction of argon condensate and cluster sizes are estimated., Prepared in cooperation with ARO, Inc., Tullahoma, Tenn., Rept. no. ARO-VKF-TR-74-13.

Homogeneous condensation of nitrogen in hypersonic expansions from a sonic orifice source was investigated using both Rayleigh scattering and electron beam fluorescence diagnostics. Using a 3-mm orifice, the source pressure range of 100 to 4000 torr was investigated for a 300 deg K source temperature. Electron beam measurements of the rotational temperature, TR, of nitrogen were used to determine onset of condensation, and both radial and axial surveys of TR were performed. Rayleigh scattering measurements were used to observe both onset of condensation and growth of clusters along the centerline, and estimates of mole or mass fractions of condensate were obtained using both diagnostic techniques. Previously published supersaturation ratios of N2 are compared., Prepared in cooperation with ARO, Inc., Tullahoma, TN. Rept. no. ARO-VKF-TR-74-12.