Definition of Blade Sections

Formatted Point Data File

Blade sections are defined in Formatted Point Data (FPD) files. The header for these file should be two space-delimited integers : \(N_{points}\) and \(N_{sections}\). \(N_{points}\) is the number of points per section (and this must be constant for each section within the file) and \(N_{sections}\) is the number of sections contained within the file. The lines after the header must take the form of three space delimited floating point numbers which represent the X,Y and Z coordinates of each point for the section.

So for example, if the header was ‘100 1’ then the file would contain a single section which consints of 100 lines. Lines 2-101 in this file would then contain the X, Y and Z co-ordinates for the section. If the head was ‘100 3’ then the file should contain 301 lines : 2-101 are the first section, 102-201 the second section and 202-301 the third section.

An example FPD file is shown below (\(N_{points}\) is 66 and \(N_{sections}\) is 1):

66 1
0.0000000 -0.0000000 0.0000000 
0.0005839 -0.0042603 0.0000000
0.0023342 -0.0084289 0.0000000
0.0052468 -0.0125011 0.0000000
0.0093149 -0.0164706 0.0000000
0.0145291 -0.0203300 0.0000000
0.0208771 -0.0240706 0.0000000
0.0283441 -0.0276827 0.0000000
0.0369127 -0.0311559 0.0000000
0.0465628 -0.0344792 0.0000000
0.0572720 -0.0376414 0.0000000
0.0690152 -0.0406310 0.0000000
0.0817649 -0.0434371 0.0000000
0.0954915 -0.0460489 0.0000000
0.1101628 -0.0484567 0.0000000
0.1257446 -0.0506513 0.0000000
0.1422005 -0.0526251 0.0000000
0.1594921 -0.0543715 0.0000000
0.1775789 -0.0558856 0.0000000
0.1964187 -0.0571640 0.0000000
0.2159676 -0.0582048 0.0000000
0.2361799 -0.0590081 0.0000000
0.2570083 -0.0595755 0.0000000
0.2784042 -0.0599102 0.0000000
0.3003177 -0.0600172 0.0000000
0.3226976 -0.0599028 0.0000000
0.3454915 -0.0595747 0.0000000
0.3686463 -0.0590419 0.0000000
0.3921079 -0.0583145 0.0000000
0.4158215 -0.0574033 0.0000000
0.4397317 -0.0563200 0.0000000
0.4637826 -0.0550769 0.0000000
0.4879181 -0.0536866 0.0000000
0.5120819 -0.0521620 0.0000000
0.5362174 -0.0505161 0.0000000
0.5602683 -0.0487619 0.0000000
0.5841786 -0.0469124 0.0000000
0.6078921 -0.0449802 0.0000000
0.6313537 -0.0429778 0.0000000
0.6545085 -0.0409174 0.0000000
0.6773025 -0.0388109 0.0000000
0.6996823 -0.0366700 0.0000000
0.7215958 -0.0345058 0.0000000
0.7429917 -0.0323294 0.0000000
0.7638202 -0.0301515 0.0000000
0.7840324 -0.0279828 0.0000000
0.8035813 -0.0258337 0.0000000
0.8224211 -0.0237142 0.0000000
0.8405079 -0.0216347 0.0000000
0.8577995 -0.0196051 0.0000000
0.8742554 -0.0176353 0.0000000
0.8898372 -0.0157351 0.0000000
0.9045085 -0.0139143 0.0000000
0.9182351 -0.0121823 0.0000000
0.9309849 -0.0105485 0.0000000
0.9427280 -0.0090217 0.0000000
0.9534372 -0.0076108 0.0000000
0.9630873 -0.0063238 0.0000000
0.9716559 -0.0051685 0.0000000
0.9791229 -0.0041519 0.0000000
0.9854709 -0.0032804 0.0000000
0.9906850 -0.0025595 0.0000000
0.9947532 -0.0019938 0.0000000
0.9976658 -0.0015870 0.0000000
0.9994161 -0.0013419 0.0000000
1.0000000 -0.0012600 0.0000000

Section Definition

A section is defined as a constant span or constant radius profile. For an axial machine it is best to define each section at a constant radius where as for a radial machine it is best to define a section at constant span. Within an FPD file sections should be defined with the lowest radius/span section first.

Sections can be split into two surfaces and generally these are the pressure surface and suction surface. The figure below shows a section of a turbine blade with the pressure and suction surfaces split at the leading and trailing edges. Each section should start at the leading edge and finish at the trailing edge.

_images/vki.png

Using FPD files it is possible to define multiple sections in one file or just a single section.