Cylindrical acoustical holography applied to full-scale jet noise.
نویسندگان
چکیده
Near-field acoustical holography methods are used to predict sound radiation from an engine installed on a high-performance military fighter aircraft. Cylindrical holography techniques are an efficient approach to measure the large and complex sound fields produced by full-scale jets. It is shown that a ground-based, one-dimensional array of microphones can be used in conjunction with a cylindrical wave function field representation to provide a holographic reconstruction of the radiated sound field at low frequencies. In the current work, partial field decomposition methods and numerical extrapolation of data beyond the boundaries of the hologram aperture are required prior to holographic projection. Predicted jet noise source distributions and directionality are shown for four frequencies between 63 and 250 Hz. It is shown that the source distribution narrows and moves upstream, and that radiation directionality shifts toward the forward direction, with increasing frequency. A double-lobe feature of full-scale jet radiation is also demonstrated.
منابع مشابه
Session 1pSPa: Nearfield Acoustical Holography (NAH) Measurements and Applications 1pSPa4. Modified statistically optimized near-field acoustical holography for jet noise characterization
Near-field acoustical holography has been shown to be a useful tool for visualizing jet noise fields. It has been applied to a full-scale jet on an installed military aircraft with promising results, but the source characteristics in the extreme near field have been difficult to characterize because of the interference of acoustic reflections off the rigid reflecting plane beneath the jet. To p...
متن کاملSession 1pNS: Noise 1pNS5. On near-field acoustical inverse measurements of partially coherent sources
The sources of jet noise have been investigated through the use of near-field array measurements. An understanding of spatial coherence properties in the jet near field leads to insight about source composition. A metric called coherence length is a useful tool for summarizing near-field coherence information. Near-field coherence lengths are presented in this work for a full-scale jet, which s...
متن کاملCharacterization of rocket and jet noise using near-field acoustic holography methods
As rockets and jets on military aircraft become more powerful, the noise they produce can lead to structural fatigue, hearing damage, and community disturbances. Noise-reduction technologies and sound radiation prediction require accurate characterization of the noise sources within rocket plumes and jets. Near-field acoustical holography techniques were used to visualize the sound field in the...
متن کاملSession 1apa: Physical Acoustics 1apa11. Partial Field Decomposition of Jet Noise Sources Using Optimally Located Virtual Refer- Ence Microphones
It is desirable to isolate independent noise sources in jets for targeted noise reduction methodologies. The application of traditional partial field decomposition (PFD) techniques to jet noise fields is useful for estimating the number of incoherent (equivalent) noise sources within a jet and for implementing near-field acoustical holography, but it does not generally provide physically meanin...
متن کاملDevelopment of a near-field acoustical holography system for aircraft jet source noise measurements
Military jet aircraft are exposing both ground maintenance personnel and the community to high levels of noise. The US Department of Defense is funding research to develop advanced modeling tools for noise reduction techniques and community noise exposure. For these tools to achieve their full potential, innovative measurement and analysis methods are necessary to characterize the jet noise sou...
متن کاملذخیره در منابع من
با ذخیره ی این منبع در منابع من، دسترسی به آن را برای استفاده های بعدی آسان تر کنید
برای دانلود متن کامل این مقاله و بیش از 32 میلیون مقاله دیگر ابتدا ثبت نام کنید
ثبت ناماگر عضو سایت هستید لطفا وارد حساب کاربری خود شوید
ورودعنوان ژورنال:
- The Journal of the Acoustical Society of America
دوره 136 3 شماره
صفحات -
تاریخ انتشار 2014