"SUMMARY OF DATA PRESENTED AND APPLICABILITY This Data Item presents information on the performance of some straight-axis@ straight-walled diffusers of concentric@ circular@ annular cross section. The names used in the Item for certain special types are given in Table 8.1 which also includes expressions for the area ratio@A2/A1@ in terms of the length ratio@ L/h1@ wall angles ?? and ??font face=""Times New Roman"" size=""1"">o@ and the inlet radius ratio@ r1(Equations (8.1) to (8.7)). The data given in the Item are derived basically for axi-symmetrical diffusers with smooth corners at entry and with the struts supporting the centre body well outside the diffuser (see Section 4.3.5). The entry flow conditions are basically fully-developed@ incompressible annular flow with Reynolds number greater than about 5X104@ free from any influence of adjacent duct components. Application of the data for other conditions is discussed in Section 4.3. The effects of diffuser geometry on the overall flow patterns in the diffusers are discussed in Section 3. Sections 4.1 and 4.2 discuss the static-pressure recovery coefficient data presented. Data are presented graphically for symmetrical diffusers@ parallel core diffusers and general type diffusers (see Table 8.1) with ?? = 5??For other types some guidance is given. The area ratio giving maximum Cpr for a given length ratio and the length ratio giving maximum Cpr for a given area ratio are shown by the C*pr and Cp*r*lines respectively. The data are estimated to be generally within ??0.1 in Cpr with the highest uncertainty in values for area ratios greater than 2. Section 5 shows how a total-pressure loss coefficient can be derived from the static-pressure recovery coefficient. The results are given in equation form only."
ESDU 75026-1975 history
1975ESDU 75026-1975 PERFORMANCE OF CIRCULAR ANNULAR DIFFUSERS IN INCOMPRESSIBLE FLOW