Low-Speed Wake Characteristics of Two-Dimensional Cascade and Isolated Airfoil Sections Page: 4 of 52
This report is part of the collection entitled: National Advisory Committee for Aeronautics Collection and was provided to UNT Digital Library by the UNT Libraries Government Documents Department.
Extracted Text
The following text was automatically extracted from the image on this page using optical character recognition software:
2 NACA TN 3771
further shown that these two parameters are significant for the correla-
tion of cascade loss data. A fundamental knowledge of blade-wake char-
acteristics was therefore found to be desirable for detailed analysis of
profile losses. A study of blade wakes is also desirable because it can
add to the general knowledge of viscous flow across cascade sections and
may be useful in understanding and analyzing blade-row interaction
effects.
The present report is concerned with the general nature of the wake
downstream of low-speed two-dimensional cascade sections. In particular,
the variation of certain properties with distance downstream of the trail-
ing edge is studied. Empirical or theoretical variations are determined
for such factors as wake minimum velocity, form factor, momentum thickness,
full thickness, total-pressure loss, and ratio of mass-averaged to area-
averaged loss. The analysis is based on available experimental data and
on available or derived theory for both isolated and cascade airfoil
sections.
SYMBOLS
a,b,d constants in equation for minimum velocity
CL lift coefficient
c chord length, ft
f,g factors in equations for analytical velocity profiles (table III)
H wake form factor, B*/8
h constant in relation for wake full thickness
i incidence angle, angle between inlet-air direction and tangent
to blade mean camber line at leading edge, deg
K wake pseudoenergy factor, k/O
k wake pseudoenergy thickness, ft
m exponent in power velocity profile relation (table III)
n coordinate normal to outlet-flow direction, ft
P total pressure, lb/sq ftaveraged defect in total pressure, lb/sq ft
Upcoming Pages
Here’s what’s next.
Search Inside
This report can be searched. Note: Results may vary based on the legibility of text within the document.
Tools / Downloads
Get a copy of this page or view the extracted text.
Citing and Sharing
Basic information for referencing this web page. We also provide extended guidance on usage rights, references, copying or embedding.
Reference the current page of this Report.
Lieblein, Seymour & Roudebush, William H. Low-Speed Wake Characteristics of Two-Dimensional Cascade and Isolated Airfoil Sections, report, October 1956; (https://digital.library.unt.edu/ark:/67531/metadc55985/m1/4/: accessed April 17, 2024), University of North Texas Libraries, UNT Digital Library, https://digital.library.unt.edu; crediting UNT Libraries Government Documents Department.