\n\tESDU 00007 develops an empirical method for predicting the drag
\nwhere the cavity length is small compared to its depth and the
\nshear flow bridges the gap between the front and rear walls, with
\nthe dividing streamline ending in a stagnation point at or near the
\ntop of the rear wall, trapping one or more vortices in the cavity
\n(i.e. open flow). A single trapped vortex is typical for
\ndepth-to-length ratios between 0.5 and 1. For lower depth-to-length
\nvalues a tandem pair of vortices can arise, while for higher
\ndepth-to-length values vertically stacked double or even triple
\nvortices may occur. Families of curves are given to suggest a lower
\nlimit of cavity depth-to-length ratio for open flow in terms of
\nfreestream Mach number and cavity width-to-length ratio. If the
\ncavity length is long compared to its depth, the shear flow enters
\nthe cavity and attaches to the floor before separating to exit over
\nthe rear wall with a stagnation point near the top of the wall
\n(i.e. closed flow); the closed flow case is treated in the
\ncompanion document, ESDU 00006. A family of curves repeated from
\nthat document is given to suggest an upper limit of cavity
\ndepth-to-length ratio for closed flow in terms of freestream Mach
\nnumber and cavity width-to-length ratio. For a given cavity width
\nand depth, at given flow conditions, as the cavity length is
\nprogressively increased from zero there is a range of values over
\nwhich, for subsonic freestream speeds, the flow type gradually
\nchanges from open to closed flow, with the flow entering the cavity
\nover the front wall but not attaching to the floor before passing
\nover the rear wall (i.e. transitional flow). For supersonic speeds
\na similar range exists but the change from open to closed flow is
\nmore complex and abrupt, passing through two intermediate stages
\n(i.e. transitional-open and transitional-closed). ESDU 00007
\ncontinues the open flow prediction method with a smooth progression
\ninto the transitional region. The interface region between
\ntransitional and closed flows, which is not precise and may need
\nthe construction of a short fairing, is discussed and illustrated
\nby means of an example. Tables give the ranges of parameters
\ncovered by the method. The prediction of the ratio of the drag
\ncoefficient, based on floor area, to the local skin friction
\ncoefficient at the cavity mid-length station (in the absence of the
\ncavity) is assessed to be within 2. However, that accuracy requires
\ncertain data to be excluded from the analysis, and for freestream
\nMach numbers greater than 0.5 their inclusion would lower the
\nagreement to within 5. The concerns with the data are discussed and
\nall the details of the analysis are explained. Worked examples
\nillustrate the use of the method. The third item in the series,
\nESDU 10016, deals with the effect on cavity drag of a pair of doors
\nopen at 90\u00b0, including the effects of three different treatments of
\nthe door leading and trailing edges\n\t<\/p>\n","protected":false},"excerpt":{"rendered":"
Drag of a Rectangular Planform Cavity in a Flat Plate with a Turbulent Boundary Layer for Mach Numbers Up to 3 – Part II: Open and Transitional Flows<\/b><\/p>\n\n\n
\n Published By<\/td>\n Publication Date<\/td>\n Number of Pages<\/td>\n<\/tr>\n \n ESDU<\/b><\/a><\/td>\n 2011-10-01<\/td>\n 57<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n","protected":false},"featured_media":557165,"template":"","meta":{"rank_math_lock_modified_date":false,"ep_exclude_from_search":false},"product_cat":[2675],"product_tag":[],"class_list":{"0":"post-557155","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\/557155","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\/557165"}],"wp:attachment":[{"href":"https:\/\/pdfstandards.shop\/wp-json\/wp\/v2\/media?parent=557155"}],"wp:term":[{"taxonomy":"product_cat","embeddable":true,"href":"https:\/\/pdfstandards.shop\/wp-json\/wp\/v2\/product_cat?post=557155"},{"taxonomy":"product_tag","embeddable":true,"href":"https:\/\/pdfstandards.shop\/wp-json\/wp\/v2\/product_tag?post=557155"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}