{"id":559373,"date":"2024-11-05T18:23:45","date_gmt":"2024-11-05T18:23:45","guid":{"rendered":"https:\/\/pdfstandards.shop\/product\/uncategorized\/esdu-960252010\/"},"modified":"2024-11-05T18:23:45","modified_gmt":"2024-11-05T18:23:45","slug":"esdu-960252010","status":"publish","type":"product","link":"https:\/\/pdfstandards.shop\/product\/publishers\/esdu\/esdu-960252010\/","title":{"rendered":"ESDU 96025:2010"},"content":{"rendered":"

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

This Item describes a method for the prediction of the drag due
\nto lift for swept wings of straight taper with camber and twist,
\nalone or in combination with a body under conditions that tend to
\ninduce leading-edge flow separation and a loss of leading-edge
\nsuction at low to moderate values of lift coefficient. It is
\napplied to wings with mild cranks through the use of an
\n\u2018equivalent' straight-tapered wing, a geometric construction that
\nis described in Addendum A of Item No. 76003 (Derivation 3). The
\nangle of attack range includes the regime where there may be a full
\nor partial loss of leading-edge suction and the formation of
\nleading-edge vortex flow, but widespread flow separation over the
\nmain part of the wing is not addressed. The method applies for
\nsubsonic flow and when the boundary-layer over the whole wing is
\nfully turbulent. The method is unsuited to hand calculations and
\nhas been programmed as ESDUpac A9625, which operates as a batch
\nfile that runs a number of other programs automatically, writing
\ntheir inputs and reading their outputs to produce a final output
\nfile from one input file.<\/p>\n

Item No. 95025 (Derivation 10) developed a method for the
\nprediction of drag due to lift for planar wings. The method invokes
\nthe concept of attainable leading-edge suction to cater for the
\neffects of wing section geometry (Derivations 17 and 18). For wings
\nof low aspect ratio the lift associated with the leading-edge
\nvortex is estimated by extended forms of the Polhamus analogy
\n(Derivations 13, 15 and 16).<\/p>\n

Derivations 20 to 22 and the recapitulation in Reference 43 show
\nthat the calculation of attainable suction for non-planar wings may
\nbe made by using the same equations that apply to planar wings
\nprovided that a reliable estimate can be made of the theoretical
\nleading-edge suction distribution. They demonstrate that this can
\nbe done by using the theoretical distribution for a planar wing of
\nidentical planform in conjunction with a corrected local angle of
\nattack. They also show that it is necessary in the calculation of
\nvortex lift to allow for the migration of the leading-edge vortex
\nas it travels back over the wing. It is not sufficient to assume
\nthat all the vortex lift acts at the leading edge, and the local
\nsurface slope is of consequence as it determines the direction of
\nthe force. The method of this Item incorporates both these
\nconcepts. The detailed calculation of the corrected angle of attack
\nfollows the technique in Derivations 20 to 22 and Reference 43. The
\nprediction of the aft migration rate of the leading-edge vortex is
\nbased on the work of Derivation 19, the simplest of the published
\noptions available. As incidence increases the loss of lift due to
\nthe vortex passing over the wing trailing edge or of vortex
\nbreakdown occurring ahead of the wing trailing edge is modified
\nthrough a single factor developed from a correlation presented in
\nReference 41.<\/p>\n

In Derivation 24 the method for estimating attainable suction
\nwas improved over the earlier versions in Derivations 17, 18 and
\n21. A final modification was reported in Reference 43. The
\nprogrammed method takes account of all these changes. Full details
\nof the development of the method are not given because the basic
\nphilosophy of the technique remains as summarised in Section 3.2 of
\nItem No. 95025. Moreover, Derivation 24 provides a comprehensive
\ndescription of the development of the whole method for attainable
\nsuction and does not simply confine itself to the improvements
\nmade. It is therefore an ideal reference for users who wish to know
\nmore of the intricacies involved.<\/p>\n

The overall model for a wing is detailed in Section 3. Section 4
\nindicates a simple extension to include wing-body configurations.
\nSection 5 discusses accuracy and applicability. Section 6 lists the
\nDerivation and References and Section 7 describes the input and
\noutput for the programmed version of the method, with examples. In
\nthe input file (see Section 7.3), after the free-stream conditions
\nand configuration geometry have been specified, some entries allow
\nthe user to alter a number of the program default settings and so
\nexamine the influence of certain parameters or calibrate prediction
\nagainst known experimental data.<\/p>\n

Appendix A sets out the formulae for the calculation of
\nleading-edge suction. Appendix B discusses the estimation of
\nlift-dependent viscous drag, which forms a secondary component of
\nthe overall drag polar. Appendix C addresses leading-edge vortex
\nmigration and breakdown.<\/p>\n","protected":false},"excerpt":{"rendered":"

Drag due to lift for non-planar swept wings up to high angles of attack at subsonic speeds<\/b><\/p>\n\n\n\n\n
Published By<\/td>\nPublication Date<\/td>\nNumber of Pages<\/td>\n<\/tr>\n
ESDU<\/b><\/a><\/td>\n2010-06-01<\/td>\n91<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n","protected":false},"featured_media":559379,"template":"","meta":{"rank_math_lock_modified_date":false,"ep_exclude_from_search":false},"product_cat":[2675],"product_tag":[],"class_list":{"0":"post-559373","1":"product","2":"type-product","3":"status-publish","4":"has-post-thumbnail","6":"product_cat-esdu","8":"first","9":"instock","10":"sold-individually","11":"shipping-taxable","12":"purchasable","13":"product-type-simple"},"_links":{"self":[{"href":"https:\/\/pdfstandards.shop\/wp-json\/wp\/v2\/product\/559373","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:featuredmedia":[{"embeddable":true,"href":"https:\/\/pdfstandards.shop\/wp-json\/wp\/v2\/media\/559379"}],"wp:attachment":[{"href":"https:\/\/pdfstandards.shop\/wp-json\/wp\/v2\/media?parent=559373"}],"wp:term":[{"taxonomy":"product_cat","embeddable":true,"href":"https:\/\/pdfstandards.shop\/wp-json\/wp\/v2\/product_cat?post=559373"},{"taxonomy":"product_tag","embeddable":true,"href":"https:\/\/pdfstandards.shop\/wp-json\/wp\/v2\/product_tag?post=559373"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}