{"id":558991,"date":"2024-11-05T18:22:37","date_gmt":"2024-11-05T18:22:37","guid":{"rendered":"https:\/\/pdfstandards.shop\/product\/uncategorized\/esdu-900232008\/"},"modified":"2024-11-05T18:22:37","modified_gmt":"2024-11-05T18:22:37","slug":"esdu-900232008","status":"publish","type":"product","link":"https:\/\/pdfstandards.shop\/product\/publishers\/esdu\/esdu-900232008\/","title":{"rendered":"ESDU 90023:2008"},"content":{"rendered":"

INTRODUCTION<\/strong><\/p>\n

Airframe noise is caused by airflow over aeroplane surfaces. It
\ndoes not include powerplant noise and therefore sets a lower limit
\nbelow which reductions in engine noise emission have no significant
\neffect on the total noise level from the aeroplane. The level of
\nairframe noise is dependent upon the aeroplane configuration. In
\nbasic terms, an aerodynamically \u2018clean' aeroplane produces less
\nnoise in the airflow than a \u2018dirty' one. The landing configuration
\nwith slats extended, flaps down and undercarriage lowered is
\ntherefore considerably more noisy than the clean configuration. An
\nillustration of the magnitude of this increase in noise level for
\nthe aeroplane described in the example in Section 8 is shown in
\nSketch 2.1. The solid curve in Sketch 2.1 represents the predicted
\nnoise spectrum for the aeroplane overhead, in the landing
\nconfiguration, and the dashed curve is for the aeroplane in the
\nclean configuration at the same location and flying at the same
\nairspeed. The breakdown of the airframe noise spectrum for the
\nlanding configuration into its constituent component spectra is
\nshown in Sketch 2.2.<\/p>\n

This Item provides a computerised method for estimating airframe
\nnoise in the far-field. The prediction method, which is a
\nsemi-empirical one, has been developed from that proposed by Fink
\n(Derivations 2 and 5) with changes to directivity and spectral
\nfunctions based on recently available data. The aeroplane geometry
\nand operating conditions are required input data. The program
\npermits the estimation of the OASPL<\/i> and of one-third
\noctave band sound pressure levels within a frequency range and over
\npolar and azimuthal angular ranges set by the user. The output
\nvalues are for free-field and still, lossless atmospheric
\nconditions. Procedures to correct for atmospheric attenuation,
\nground reflection and lateral attenuation in still atmospheric
\nconditions may be found in References 8, 9, 10 and 12. To account
\nfor wind and temperature gradients the method described in
\nReference 11 may be used.<\/p>\n","protected":false},"excerpt":{"rendered":"

Airframe Noise Prediction<\/b><\/p>\n\n\n\n\n
Published By<\/td>\nPublication Date<\/td>\nNumber of Pages<\/td>\n<\/tr>\n
ESDU<\/b><\/a><\/td>\n2008-12<\/td>\nNA<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n","protected":false},"featured_media":0,"template":"","meta":{"rank_math_lock_modified_date":false,"ep_exclude_from_search":false},"product_cat":[2675],"product_tag":[],"class_list":{"0":"post-558991","1":"product","2":"type-product","3":"status-publish","5":"product_cat-esdu","7":"first","8":"instock","9":"sold-individually","10":"shipping-taxable","11":"purchasable","12":"product-type-simple"},"_links":{"self":[{"href":"https:\/\/pdfstandards.shop\/wp-json\/wp\/v2\/product\/558991","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/pdfstandards.shop\/wp-json\/wp\/v2\/product"}],"about":[{"href":"https:\/\/pdfstandards.shop\/wp-json\/wp\/v2\/types\/product"}],"wp:attachment":[{"href":"https:\/\/pdfstandards.shop\/wp-json\/wp\/v2\/media?parent=558991"}],"wp:term":[{"taxonomy":"product_cat","embeddable":true,"href":"https:\/\/pdfstandards.shop\/wp-json\/wp\/v2\/product_cat?post=558991"},{"taxonomy":"product_tag","embeddable":true,"href":"https:\/\/pdfstandards.shop\/wp-json\/wp\/v2\/product_tag?post=558991"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}