Design of an Advanced Inlet Liner for the Quiet Technology Demonstrator 3

The utilization of advanced fan designs (including higher bypass ratios) and shorter engine nacelles has highlighted a need for increased fan noise reduction over a broad frequency range. Thus, improved broadband liner designs must account for these constraints and take advantage of novel liner configurations. With these observations in mind, the development and assessment of a broadband acoustic liner optimization process has been pursued through a series of design and experimental studies. In this work, an advanced inlet liner was designed for a Boeing 737MAX-7 to reduce drag and to improve the broadband noise reduction relative to conventional liners in use today. Specifically, a three layer liner was designed, fabricated, and flight tested as part of the Quiet Technology Demonstrator 3 flight test program. Initial tonal predictions captured the behavior of the measured data very well and both prediction and measurements show an increased acoustic benefit at larger observer angles, particularly at the takeoff condition. Ultimately, flight test results showed the three degree-of-freedom liner to provide a 3.2 EPNdB cumulative inlet component benefit and a 0.7 EPNdB cumulative airplane benefit over the production liner. This excellent result provides valuable validation of the broadband liner design process, as well as the enhancements made to the overall approach. It also illustrates the value of the design process in concurrently evaluating various liner designs (i.e., SDOF, MDOF, etc.) and their application to various locations. Thus, the design process may be applied with further confidence to investigate novel liner configurations in future design studies

An Investigation of Bifurcation Acoustic Treatment Effects on Aft-Fan Engine Nacelle Noise

Increasing air traffic and more stringent aircraft noise regulations continue to expand requirements on aircraft noise reduction capabilities for conventional and unconventional aircraft configurations. A major component of the overall aircraft noise is the sound associated with the propulsion system mounted in the engine nacelle. Acoustic liners mounted in the aircraft engine nacelles provide a significant portion of the current fan noise reduction. However, they must be further optimized if challenging noise reduction goals are to be achieved. One area within the aft bypass duct that may be an excellent candidate for increased attention is the acoustic treatment on the engine bifurcations (i.e., engine pylon and lower bifurcation). This paper describes a fundamental study of the effects of bifurcation treatment on simulated aft fan noise, as well as the validation of numerical tools to predict such effects. Five bifurcation configurations (four treated and one hardwall) were fabricated and tested in the NASA Langley Curved Duct Test Rig. Results show that mode scattering may occur due to both the presence of the bifurcation, as well as variable impedance distributions on the bifurcation surface. Future work will also include optimization of bifurcation treatments for testing in the Curved Duct Test Rig. These initial results are promising and this work provides valuable information for further study and improvement of the performance of bifurcation acoustic treatments

Assessment of Axial Wave Number and Mean Flow Uncertainty on Acoustic Liner Impedance Education

A key parameter in designing and assessing advanced broadband acoustic liners to achieve the current and future noise reduction goals is the acoustic impedance presented by the liner. This parameter, intrinsic to a specific liner configuration, is dependent on sound pressure level and grazing flow velocity. Current impedance eduction approaches have, in general, provided excellent results and continue to be employed throughout the acoustic liner community. However, some recent applications have indicated a possible dependence of the educed impedance on the direction of incident waves relative to the mean flow. The purpose of the current study is to investigate this unexpected behavior for various impedance eduction methods based on the Pridmore-Brown and convected Helmholtz equations. Specifically, the effects of flow profile and axial wavenumber uncertainties on educed impedances for upstream and downstream sources are investigated. The uniform flow results demonstrate the importance of setting a correct Mach number value in obtaining consistent educed impedances for upstream and downstream sources. In fact, the consistency of results over the two source locations was greatly improved by a slight modification of the uniform flow Mach number. In addition, uncertainty in educed axial wavenumber was also illustrated to correlate well with differences in the educed impedances, even with modified uniform flow Mach number. Finally, while less straightforward than in the uniform flow case, it appears that modification of the mean flow profile may also improve consistency of results for upstream and downstream results when shear flow is included

Large Deformation Behavior of Long Shallow Cylindrical Composite Panels

An exact solution is presented for the large deformation response of a simply supported orthotropic cylindrical panel subjected to a uniform line load along a cylinder generator. The cross section of the cylinder is circular and deformations up to the fully snapped through position are investigated. The orthotropic axes are parallel to the generator and circumferential directions. The governing equations are derived using laminated plate theory, nonlinear strain-displacement relations, and applying variational principles. The response is investigated for the case of a panel loaded exactly at midspan and for a panel with the load offset from midspan. The mathematical formulation is one dimensional in the circumferential coordinate. Solutions are obtained in closed-form. An experimental apparatus was designed to load the panels. Experimental results of displacement controlled tests performed on graphite-epoxy curved panels are compared with analytical predictions

Broadband Liner Optimization for the Source Diagnostic Test Fan

The broadband component of fan noise has grown in relevance with the utilization of increased bypass ratio and advanced fan designs. Thus, while the attenuation of fan tones remains paramount, the ability to simultaneously reduce broadband fan noise levels has become more appealing. This paper describes a broadband acoustic liner optimization study for the scale model Source Diagnostic Test fan. Specifically, in-duct attenuation predictions with a statistical fan source model are used to obtain optimum impedance spectra over a number of flow conditions for three liner locations in the bypass duct. The predicted optimum impedance information is then used with acoustic liner modeling tools to design liners aimed at producing impedance spectra that most closely match the predicted optimum values. Design selection is based on an acceptance criterion that provides the ability to apply increased weighting to specific frequencies and/or operating conditions. Typical tonal liner designs targeting single frequencies at one operating condition are first produced to provide baseline performance information. These are followed by multiple broadband design approaches culminating in a broadband liner targeting the full range of frequencies and operating conditions. The broadband liner is found to satisfy the optimum impedance objectives much better than the tonal liner designs. In addition, the broadband liner is found to provide better attenuation than the tonal designs over the full range of frequencies and operating conditions considered. Thus, the current study successfully establishes a process for the initial design and evaluation of novel broadband liner concepts for complex engine configurations

Flight Test Methodology for NASA Advanced Inlet Liner on 737MAX-7 Test Bed (Quiet Technology Demonstrator 3)

This paper describes the acoustic flight test results of an advanced nacelle inlet acoustic liner concept designed by NASA Langley, in a campaign called Quiet Technology Demonstrator 3 (QTD3). NASA has been developing multiple acoustic liner concepts to benefit acoustics with multiple-degrees of freedom (MDOF) honeycomb cavities, and lower the excrescence drag. Acoustic and drag performance were assessed at a lab-scale, flow duct level in 2016. Limitations of the lab-scale rig left open-ended questions regarding the in-flight acoustic performance. This led to a joint project to acquire acoustic flyover data with this new liner technology built into full scale inlet hardware containing the NASA MDOF Low Drag Liner. Boeing saw an opportunity to collect the acoustic flyover data on the 737 MAX-7 between certification tests at no impact to the overall program schedule, and successfully executed within the allotted time. The flight test methodology and the test configurations are detailed and the acoustic analysis is summarized in this paper. After the tone and broadband deltas associated with the inlet hardware were separated and evaluated, the result was a significant decrease in cumulative EPNL (Effective Perceived Noise Level)

The North American Transportation Security Center – SERRI Analysis Update

Executive Summary There are over 800,000 hazardous materials (hazmat) shipments over the nation’s roads each day. According to the U.S. Department of Homeland Security (DHS), terrorist activity related to the transportation of hazardous materials represents a significant threat to public safety and the nation’s critical infrastructure. Specifically, the federal government has identified the government’s inability to track hazmat shipments on a real-time basis as a significant security vulnerability. In 2004, the U.S. Federal Motor Carrier Safety Administration (FMCSA) completed a study to determine if “smart truck” technology such as GPS tracking, wireless modems, panic buttons, and on-board computers could be used to enhance hazmat shipment security. The FMCSA study concluded that “smart truck” technology will be highly effective in protecting hazmat shipments from terrorists. The FMCSA study also concluded that “smart truck” technology deployment will produce a huge security benefit and an overwhelmingly positive return on investment for hazmat carriers. The FMCSA study led to the U.S. Transportation Security Administration’s (TSA) Hazmat Truck Security Pilot (HTSP). This congressionally mandated pilot program was undertaken to demonstrate if a hazmat truck tracking center was feasible from a technology and systems perspective. The HTSP project team built a technology prototype of a hazmat truck tracking system to show that “smart truck” technology could be crafted into an effective and efficient system for tracking hazmat shipments. The HTSP project team also built the Universal Communications Interface – the XML gateway for hazmat carriers to use to provide data to a centralized truck tracking center. In August 2007, Congress enacted the 9/11 Act (PL110-53) that directs TSA to develop a program - consistent with the Hazmat Truck Security Pilot - to facilitate the tracking of motor carrier shipments of security-sensitive materials. In June 2008, TSA took a major step forward in establishing a national hazmat security program by issuing guidance for shipments of Tier 1 Highway Security Sensitive Materials (HSSMs), the riskiest shipments from a security perspective. TSA’s Tier 1 HSSM guidance includes Security Action Items which specify security measures – including vehicle tracking – that TSA believes are prudent security measures for shippers and carriers to follow. Compliance with TSA’s Tier 1 HSSM guidance is voluntary but TSA is expected to issue regulations based on the Tier 1 HSSM Security Action Items that will make compliance mandatory. Establishment of a Tier 1 HSSM truck tracking center is critical to implementation of a Tier 1 HSSM regulatory program based on the Security Action items by TSA. The HTSP technology prototype was an excellent first step toward an operational Tier 1 HSSM truck tracking system, however, it falls far short of what TSA needs in an operational system. The Kentucky Transportation Center at the University of Kentucky completed a study December 2008 that examined market drivers that would influence the design and operation of a Tier 1 HSSM truck tracking system. The study was funded by the South East Region Research Initiative (SERRI). The objective of this deliverable is to update the SERRI report with a specific focus on two item: new or enhanced fleet tracking vendor product and service offerings; and programmatic conditions that have changed since December 200

The North American Transportation Security Center – Technology Prototype Gap Analysis

Executive Summary There are over 800,000 hazardous materials (hazmat) shipments over the nation’s roads each day. According to the U.S. Department of Homeland Security (DHS), terrorist activity related to the transportation of hazardous materials represents a significant threat to public safety and the nation’s critical infrastructure. Specifically, the federal government has identified the government’s inability to track hazmat shipments on a real-time basis as a significant security vulnerability. In 2004, the U.S. Federal Motor Carrier Safety Administration (FMCSA) completed a study to determine if “smart truck” technology such as GPS tracking, wireless modems, panic buttons, and onboard computers could be used to enhance hazmat shipment security. The FMCSA study concluded that “smart truck” technology will be highly effective in protecting hazmat shipments from terrorists. The FMCSA study also concluded that “smart truck” technology deployment will produce a huge security benefit and an overwhelmingly positive return on investment for hazmat carriers. The FMCSA study led to the U.S. Transportation Security Administration’s (TSA) Hazmat Truck Security Pilot (HTSP). This congressionally mandated pilot program was undertaken to demonstrate if a hazmat truck tracking center was feasible from a technology and systems perspective. The HTSP project team built a technology prototype of a hazmat truck tracking system to show that “smart truck” technology could be crafted into an effective and efficient system for tracking hazmat shipments. The HTSP project team also built the Universal Communications Interface – the XML gateway for hazmat carriers to use to provide data to a centralized truck tracking center. In August 2007, Congress enacted the 9/11 Act (PL110-53) that directs TSA to develop a program - consistent with the Hazmat Truck Security Pilot - to facilitate the tracking of motor carrier shipments of security-sensitive materials. In June 2008, TSA took a major step forward in establishing a national hazmat security program by issuing guidance for shipments of Tier 1 Highway Security Sensitive Materials (HSSMs), the riskiest shipments from a security perspective. TSA’s Tier 1 HSSM guidance includes Security Action Items which specify security measures – including vehicle tracking – that TSA believes are prudent security measures for shippers and carriers to follow. Compliance with TSA’s Tier 1 HSSM guidance is voluntary but TSA is expected to issue regulations based on the Tier 1 HSSM Security Action Items that will make compliance mandatory. Establishment of a Tier 1 HSSM truck tracking center is critical to implementation of a Tier 1 HSSM regulatory program based on the Security Action items by TSA. The HTSP technology prototype was an excellent first step toward an operational Tier 1 HSSM truck tracking system, however, it falls far short of what TSA needs in an operational system. This deliverable examines the “gaps” between the HTSP technology prototype and an operational Tier 1 HSSM truck tracking system. It draws upon the work of an Independent Verification and Validation contractor that evaluated the HTSP technology prototype. It also examines TSA needs related to implementation of a regulatory program based on Tier 1 HSSM Security Action Items