{"id":559441,"date":"2024-11-05T18:23:58","date_gmt":"2024-11-05T18:23:58","guid":{"rendered":"https:\/\/pdfstandards.shop\/product\/uncategorized\/esdu-970302011\/"},"modified":"2024-11-05T18:23:58","modified_gmt":"2024-11-05T18:23:58","slug":"esdu-970302011","status":"publish","type":"product","link":"https:\/\/pdfstandards.shop\/product\/publishers\/esdu\/esdu-970302011\/","title":{"rendered":"ESDU 97030:2011"},"content":{"rendered":"

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

This Item is the third in a sequence dealing with the VGK
\naerofoil method. The Item describes the use of VGK to estimate a
\nseparation boundary for two-dimensional aerofoils in transonic flow
\nin terms of lift coefficient and freestream Mach number. The basis
\nof the Item is the method described in Transonic Data Memorandum
\nNo. 81020 (Reference 1), and the separation boundary corresponds to
\nconditions on the upper surface of the aerofoil for which the shock
\nstrength and the adverse pressure gradient(s) are sufficiently
\nsevere for the trailing-edge pressure coefficient, relative to its
\ntrend with increasing lift coefficient or Mach number in attached
\nflow, to have decreased by 0.05.<\/p>\n

The full description of the underlying principles and
\nlimitations of the method, which is essentially based on
\n\u2018calibrating' VGK results against experimental data, is given in
\nReference 1. The present describes only the detailed organisation
\nof the computation involving VGK runs so as to obtain points on the
\nseparation boundary in a reliable and efficient way. For a
\ndescription of the principles and typical results of the VGK
\nmethod, reference should be made to Part 1 of the sequence of Items
\n(ESDU 96028), whilst details of the various types of VGK runs, the
\nnaming convention and functions of various files and the use of the
\nprogram VGKCON (the VGK \u2018control' program) are given in Part 2
\n(ESDU 96029).<\/p>\n

The estimation of a single point on an aerofoil separation
\nboundary requires a number of VGK runs to be performed. These runs
\nconstitute a \u2018sequence'. The first of such runs would normally
\nrelate to a combination of Mach number and incidence at which there
\nwere significant positive margins in terms of both the
\n\u2018shock-upstream criterion' and the \u2018trailing-edge criterion'. These
\ncriteria are reproduced from Reference 1 as Figures 1a and 1b,
\nwhere examples of positive margins are indicated. Successive VGK
\nruns in the sequence are carried out at the same Mach number, with
\nvarious values of incidence, until two successive VGK runs yield
\none or other of the margins sufficiently close to zero. (Two
\nsuccessive runs are required so as to ensure that VGK has
\nadequately converged \u2013 see Section 4.) The values of Mach number
\nand lift coefficient of the last VGK run in the sequence then
\nconstitute the single point on the separation boundary. The
\nsequence of VGK runs is controlled by a Fortran program, SEPCON.
\nThis program produces a record of the flow conditions and criterion
\nmargins of the VGK runs, and at each stage in the sequence produces
\nthe files necessary for the next VGK run. The organisation of the
\ncommands to execute the VGK and SEPCON programs in a batch file is
\ndescribed in Section 5. Procedures for obtaining a number of points
\non an aerofoil separation boundary are also presented.<\/p>\n

Estimated separation boundaries obtained using the present
\nmethod are presented and compared with observed results in Section
\n6.<\/p>\n","protected":false},"excerpt":{"rendered":"

VGK Method for Two-Dimensional Aerofoil Sections – Part 3: Estimation of a Separation Boundary in Transonic Flow<\/b><\/p>\n\n\n\n\n
Published By<\/td>\nPublication Date<\/td>\nNumber of Pages<\/td>\n<\/tr>\n
ESDU<\/b><\/a><\/td>\n2011-02<\/td>\n29<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n","protected":false},"featured_media":559450,"template":"","meta":{"rank_math_lock_modified_date":false,"ep_exclude_from_search":false},"product_cat":[2675],"product_tag":[],"class_list":{"0":"post-559441","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\/559441","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\/559450"}],"wp:attachment":[{"href":"https:\/\/pdfstandards.shop\/wp-json\/wp\/v2\/media?parent=559441"}],"wp:term":[{"taxonomy":"product_cat","embeddable":true,"href":"https:\/\/pdfstandards.shop\/wp-json\/wp\/v2\/product_cat?post=559441"},{"taxonomy":"product_tag","embeddable":true,"href":"https:\/\/pdfstandards.shop\/wp-json\/wp\/v2\/product_tag?post=559441"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}