Investigation of Twin Jet Aeroacoustic Properties in the Presence of a Hybrid Wing Body Shield

In preparation for upcoming wind tunnel acoustic experiments of a Hybrid Wing Body (HWB) vehicle with two jet engine simulator units, a series of twin jet aeroacoustic investigations were conducted leading to increased understanding and risk mitigation. A previously existing twin jet nozzle system and a fabricated HWB aft deck fuselage are combined for a 1.9% model scale study of jet nozzle spacing and jet cant angle effects, elevon deflection into the jet plume, and acoustic shielding by the fuselage body. Linear and phased array microphone measurements are made, and data processing includes the use of DAMAS (Deconvolution Approach for the Mapping of Acoustic Sources). Closely-spaced twin jets with a 5 inward cant angle exhibit reduced noise levels compared to their parallel flow counterparts at similar and larger nozzle spacings. A 40 elevon deflection into the twin jet plume, which is required for HWB ground rotation, can significantly increase upstream noise levels (more than 5 dB OASPL) with only minimal increases in the downstream direction. Lastly, DAMAS processing can successfully measure the noise source distribution of multiple shielded jet sources

Investigation of Flow Conditioners for Compact Jet Engine Simulator Rig Noise Reduction

The design requirements for two new Compact Jet Engine Simulator (CJES) units for upcoming wind tunnel testing lead to the distinct possibility of rig noise contamination. The acoustic and aerodynamic properties of several flow conditioner devices are investigated over a range of operating conditions relevant to the CJES units to mitigate the risk of rig noise. An impinging jet broadband noise source is placed in the upstream plenum of the test facility permitting measurements of not only flow conditioner self-noise, but also noise attenuation characteristics. Several perforated plate and honeycomb samples of high porosity show minimal self-noise but also minimal attenuation capability. Conversely, low porosity perforated plate and sintered wire mesh conditioners exhibit noticeable attenuation but also unacceptable self-noise. One fine wire mesh sample (DP450661) shows minimal selfnoise and reasonable attenuation, particularly when combined in series with a 15.6 percent open area (POA) perforated plate upstream. This configuration is the preferred flow conditioner system for the CJES, providing up to 20 dB of broadband attenuation capability with minimal self-noise

High Bypass Ratio Jet Noise Reduction and Installation Effects Including Shielding Effectiveness

An experimental investigation was performed to study the propulsion airframe aeroacoustic installation effects of a separate flow jet nozzle with a Hybrid Wing Body aircraft configuration where the engine is installed above the wing. Prior understanding of the jet noise shielding effectiveness was extended to a bypass ratio ten application as a function of nozzle configuration, chevron type, axial spacing, and installation effects from additional airframe components. Chevron types included fan chevrons that are uniform circumferentially around the fan nozzle and T-fan type chevrons that are asymmetrical circumferentially. In isolated testing without a pylon, uniform chevrons compared to T-fan chevrons showed slightly more low frequency reduction offset by more high frequency increase. Phased array localization shows that at this bypass ratio chevrons still move peak jet noise source locations upstream but not to nearly the extent, as a function of frequency, as for lower bypass ratio jets. For baseline nozzles without chevrons, the basic pylon effect has been greatly reduced compared to that seen for lower bypass ratio jets. Compared to Tfan chevrons without a pylon, the combination with a standard pylon results in more high frequency noise increase and an overall higher noise level. Shielded by an airframe surface 2.17 fan diameters from nozzle to airframe trailing edge, the T-fan chevron nozzle can produce reductions in jet noise of as much as 8 dB at high frequencies and upstream angles. Noise reduction from shielding decreases with decreasing frequency and with increasing angle from the jet inlet. Beyond an angle of 130 degrees there is almost no noise reduction from shielding. Increasing chevron immersion more than what is already an aggressive design is not advantageous for noise reduction. The addition of airframe control surfaces, including vertical stabilizers and elevon deflection, showed only a small overall impact. Based on the test results, the best overall nozzle configuration design was selected for application to the N2A Hybrid Wing Body concept that will be the subject of the NASA Langley 14 by 22 Foot Subsonic Tunnel high fidelity aeroacoustic characterization experiment. The best overall nozzle selected includes T-fan type chevrons, uniform chevrons on the core nozzle, and no additional pylon of the type that created a strong acoustic effect at lower bypass ratios. The T-fan chevrons are oriented azimuthally away from the ground observer locations. This best overall nozzle compared to the baseline nozzle was assessed, at equal thrust, to produce sufficient installed noise reduction of the jet noise component to enable the N2A HWB to meet NASA s noise goal of 42 dB cumulative below Stage 4

Phase I Cultural Resources Investigations at Justiceburg Resevoir on the Double Mountain Fork of the Brazos River, Garza and Kent Counties, Texas Volume II

The prehistoric site descriptions are divided into three sections: Garza County, Kent County, and Isolated Finds. All sites are described fully in a telegraphic format in order to conserve space. The descriptions are organized by county in alphabetical order and in numerical order of site within each county. Information for each site 1s organized into six headings: location, description, features, cultural materials observed/collected, shovel test data, and assessment/recommendations. The determination of the percentage of the site remaining intact is based on in-field observations of the postulated original areal extent of the site versus what is still potentially intact. Assessments are based on each site\u27s individual merits and are stated in terms of eligibility for listing on the National Register of Historic Places. These assessments were made by the Project Archeologist and the Principal Investigator based on a site-by-site review. Two categories of eligibility include: potentially eligible (sites with excellent to unknown research potential) , and not eligible (sites with little or no further research potential). Research potential is derived from each site I s potential to contribute to the resolution of the questions posed in the Research Design (Chapter 5). While most of the research potential categories are reasonably clear, the unknown category should be more fully explained. Sites with unknown potential are those that are buried, lack exposed features, and failed to yield temporally or functionally diagnostic materials. The unknownII designation refers to the inability (based on extant data) to specify which research questions a site may appropriately address rather than a lack of any research potential. Assessments also may refer to exotics. This term is used to identify materials or artifacts that were imported into the local area. Included are such items as obsidian, Alibates agate, Tecovas jasper, and nonlocal ceramics. Recommendations are provided on the basis of each site\u27s assessment. These do not consider the suggested sampling strategy described in Chapter 13, Recommendations/Treatment Plan. Isolated Finds were thoroughly documented in the field and were assigned trinomial site numbers to facilitate record Jceeping; however, they are not felt to be worthy of extended descriptions for reporting purposes. Therefore, this category of sites is treated in highly abbreviated form in a separate section following the site descriptions. Information provided for Isolated Finds includes: site number, location, landform, elevation, area, description, and material type. Isolated finds are defined as any single surface artifact or feature with no associated materials or features, or surface sites with a density of cultural materials less than one item in 20 rna. These finds generally are highly disturbed, redeposited, or lack intact context. No shovel testing was done at Isolated Finds, except at sites 41GR411, 41GR482, 41GRS19, 41GRS32, 41KT46, and 41KT71, where all tests excavated were negative. Only three of these Isolated Finds are dated. These sites are considered to retain little interpretive value beyond the survey level, and none require further work. Because of this, Isolated Finds are not considered eligible for listing on the National Register of Historic Places. Finally, abbreviations are used throughout the site descriptions. Those referring to roads, distances, elevations, and cardinal directions are self-explanatory. However, two others require explanation. GRC refers to Grand River Consultants, Inc., a firm located in Grand River, Colorado, which performed limited archeological survey at Justiceburg in 1982. NRHP refers to the National Register of Historic Places; this phrase is abbreviated to save space since it must be used in the assessments of each individual site

Single Event Effects Testing of a Commercial-Off-The-Shelf Analog-to-Digital Converter in a Camera Application

Single event effect data is presented on the Analog Devices AD7984. The recent heavy-ion test results showcase application-specific results for the commercial part in its intended application

Active Noise Control of Radiated Noise from Jets Originating NASA

The reduction of jet noise using a closed-loop active noise control system with highbandwidth active chevrons was investigated. The high frequency energy introduced by piezoelectrically-driven chevrons was demonstrated to achieve a broadband reduction of jet noise, presumably due to the suppression of large-scale turbulence. For a nozzle with one active chevron, benefits of up to 0.8 dB overall sound pressure level (OASPL) were observed compared to a static chevron nozzle near the maximum noise emission angle, and benefits of up to 1.9 dB OASPL were observed compared to a baseline nozzle with no chevrons. The closed-loop actuation system was able to effectively reduce noise at select frequencies by 1-3 dB. However, integrated OASPL did not indicate further reduction beyond the open-loop benefits, most likely due to the preliminary controller design, which was focused on narrowband performance

TESS Data Release Notes: Sector 17, DR24

This release note discusses the science data products produced by the Science Processing Operations Center at Ames Research Center from Sector 17 observations made with the TESS spacecraft and cameras as a means to document instrument performance and data characteristics

TESS Data Release Notes: Sector 18 DR25

This release note discusses the science data products produced by the Science Processing Operations Center at Ames Research Center from Sector 18 observations made with the TESS spacecraft and cameras as a means to document instrument performance and data characteristics

Olfactory function in migraine both during and between attacks.

INTRODUCTION: People with migraine often report being osmophobic, both during and between acute migraine attacks. It is not clear, however, whether such reports are associated with changes in olfaction such as hyperosmia, as measured by psychophysical testing. In this case-control study we quantitatively assessed olfactory identification ability, which correlates with threshold tests of olfactory acuity, in patients with migraine at baseline (no headache), during migraine episodes, and after a treated attack and compared the test scores to those of matched control subjects. METHODS: Fifty episodic migraine subjects and 50 and sex- and age-matched controls without headache were tested. All completed the University of Pennsylvania Smell Identification Test (UPSIT), a standardized and well-validated olfactory test. RESULTS: At baseline, the UPSIT scores did not differ significantly between the migraine and control study groups (median paired score difference: -1, p = 0.18). During migraine attacks, a minority of migraine subjects (eight of 42) developed microsmia (i.e. lower test scores by at least four points), suggesting that, as compared to their matched controls, olfactory acuity was somewhat impaired during migraine attacks (p = 0.02). This difference was less pronounced and not statistically significant after a successfully treated attack (p = 0.15). DISCUSSION: People with episodic migraine were found to have similar olfactory function as age- and sex-matched controls, but a minority exhibit microsmia or hyposmia during acute attacks. The cause of this dysfunction is unknown, but could relate to autonomic symptoms, limbic system activation, or disorders of higher order sensory processing