Engineering topics

Lennart Hultgren

Publications and source records attributed to Lennart Hultgren.

6 records

NASA NTRS2023

Acoustics Technical Working Group and UAM Noise Working Group Proceedings

The NASA Acoustics Technical Working Group Meeting originally started as a program planning meeting in 1992 and has grown through the years. The purpose of these biannual meetings is to foster communication and collaboration among NASA researchers and their university, industry, and government colleagues on activities and work of current and future mutual interest. The NASA-led Urban Air Mobility (UAM) Noise Working Group (UNWG) Meeting began in 2018 as a one-day meeting immediately following the Acoustics Technical Working Group Meeting. The UNWG utilizes four subgroups that conduct regular meetings throughout the year to focus on challenges facing UAM vehicles for community noise and acceptance. The four subgroups coordinate research for development of noise prediction tools/noise reduction technologies, ground and flight test methods, human response and metrics, and regulations and policy (led by the FAA). This work is a compilation of the presentations given at ATWG/UNWG Fall 2022 held in person and via Teams at NASA Glenn Research Center. All NASA content was previously submitted through STRIVES for public presentation. This is merely a compilation. Non-NASA content has permission to distribute. Slide 208 video is included in the Available Downloads as Medial.MOV.

Advanced Air Mobility↗

NASA NTRSDate not supplied

Learjet Flight Test Update

The presentation provides an update on progress towards an acoustic test with a Lear 25 aircraft. The intent of the test is to acquire data that will be used to determine the ability to predict jet noise for future supersonic aircraft at takeoff from scale-model data acquired in wind tunnels. Flight and instrumentation details are provided for the flight test planned for 2022.

Electric Motor Noise↗

NASA NTRSDate not supplied

Impact of Future Low-Emissions Combustor Technology on Acoustic Scaling Laws

The work is a summary and further analysis of unlimited-rights acoustic data acquired under NRA Contract NNC16CA39C (September 2016 - November2019) with United Technologies (now Raytheon Technologies) Research Center, East Hartford, Connecticut. NASA/CR-20205011099/VOL1, https://ntrs.nasa.gov/citations/20205011099. The overall goal of the Contract was to develop a first-of-its- kind database of detailed unsteady measurements characterizing noise sources of far-term advanced low-emissions aero-combustors. The program addressed the need for fundamental combustion-noise experiments which, in the near term, enable improvements to reduced-order models for use in system level noise assessments at the preliminary design stage for advanced air transport vehicles. In addition, optical measurement techniques were refined and validated for usage at the higher pressures and temperatures relevant to future combustor designs. In the long term, results from this program can be utilized to validate high-fidelity prediction methods suited for detailed multi-disciplinary acoustics/emissions combustor design. This presentation concentrates on one aspect of the overall project, namely an examination of the legacy scaling laws for broadband combustor noise.

aeroacoustics, turbomachinery noise, combustor noi↗

NASA NTRSDate not supplied

Learjet Test Update

An update on the Learjet acoustic flight test was presented. The intent of the effort was to acquire flight data for the development of flight corrections to scale-model data. The flights were completed on September 8, 2022. Weather measurements were acquired with a combination of an instrumented drone and a ground based LiDAR system. Acquisition of comparative scale-model data will be completed on October 7, 2022.

jet noise↗

NASA NTRSDate not supplied

Moog S-250 Vehicle Hover Test Update

Acoustic measurements were made with the Moog SureFly vehicle in hover and for the vehicle performing a combined takeoff and landing maneuver. The objectives of the effort were to identify the far field, obtain data to construct a noise hemisphere for prediction tool validation, and to obtain out-and back data for use in perceived noise studies. Vehicle telemetry data and future plans for the acoustic analysis were presented.

Urban Air Mobility Noise↗

NASA NTRSDate not supplied

An Initial Vibro-Acoustic Model for Predicting Electric Motor Noise

A system-level tool to predict electric motor noise, suitable for trade studies of eVTOL and UAM aircraft, does not exist. This work describes the ongoing effort to develop such a tool. It utilizes a 3 phase prediction routine that models the electro-magnetic interactions of the electric motor, the resulting structural vibrations of the motor rotor, and finally the acoustic propagation generated by those structural vibrations.

Electric Motor Noise↗