Lewis R.I. Turbomachinery Performance Analysis
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304
Appendix H
I1.10
Contents of data file rawdata
1
37
0.000000 0.000000
0.001263 0.015536
0.018483 0.038649
0.051934 0.066698
0.100736 0.096883
0.163370 0.125813
0.237550 0.150439
0.320445 0.168477
0.408956 0.178613
0.500000 0.179675
0.590410 0.171342
0.677138 0.154552
0.757434 0.131014
0.828941 0.103156
0.889792 0.074039
0.938420 0.046618
0.973142 0.022915
0.993362 0.006035
1.000000 0.000000
0.991446 0.002648
0.966550 0.010530
0.927606 0.024107
0.876253 0.041388
0.813847 0.058684
0.742566 0.073427
0.664882 0.083936
0.583238 0.089055
0.500000 0.088275
0.417395 0.081783
0.337535 0.070011
0.262450 0.054002
0.193843 0.036027
0.133219 0.018544
0.082040 0.004027
0.041824 -0.005204
0.013930 -0.006854
0.000000 0.000000
Number of profiles
Number of (x3r) profile coordinates
37 (xfr) coordinates
This file contains final profile coordinates recorded clockwise around the blade
perimeter, beginning and ending at the leading edge. The profile is set at zero stagger
as illustrated in Fig. II.3(c).
It is also possible to create the file rawdata by using the blade design and stacking
program STACK. In this case up to ten profiles may be designed and the first
parameter in the above data set accordingly followed by that number of
(x,y)
data
sets. CASCADE may then be used to flow-analyse any of these. Simply follow the
instructions presented on the screen.
H.11 Sample contents of output file testdata for the default design
305
I1.11
Sampl e contents of output file testdata for the
default design
The following contents of the output file testdata were obtained by running the
program CASCADE and then using the menu sequence Design/analyse ... Flow
analysis to complete the blade design and fluid flow calculation for the unaltered
default cascade.
This file contains a complete record of all the work which is undertaken in a given
sitting before finally quitting and is thus very valuable for later review of your
intermediate stages in developing a cascade design. If you wish to keep it for later
use,
remember to copy it into another file for safe keeping!
Each time you start a new
run of CASCADE the file testdata is closed and re-opened!
***** Record of Design Work *****
New
Case
***** Camber Line and Half Thickness *****
x/1 yc2 half yt~
0.007596 0.004341 0.012862
0.030154 0.016723 0.024839
0.066987 0.035362 0.034763
0.116978 0.057714 0.042403
0.178606 0.080920 0.047408
0.250000 0.102220 0.049800
0.328990 0.119244 0.049969
0.413176 0.130198 0.048598
0.500000 0.133975 0.045700
0.586824 0.130198 0.041300
0.671010 0.119244 0.035836
0.750000 0.102220 0.029737
0.821394 0.080920 0.023481
0.883022 0.057714 0.017673
0.933013 0.035362 0.012487
0.969846 0.016723 0.007015
0.992404 0.004341 0.001945
***** Design Parameters *****
Profile thickness is the C4 base profile
Profile thickness scale = 1.0
Camber line type is circular arc
x/1 of maximum camber= 0.5
Camber angle theta = 60.0
Stagger angle lamda = 45.0
Pitch/chord ratio t/1 = 1.0
Fluid inlet angle betal = 60.0
306
Appendix H
***** Blade Profile *****
x y
0.000631 0.007768
0.009873 0.027093
0.035209 0.052673
0.076335 0.081790
0.132053 0.111348
0.200460 0.138126
0.278997 0.159458
0.364701 0.173545
0.454478 0.179144
0.545205 0.175508
0.633774 0.162947
0.717286 0.142783
0.793188 0.i17085
0.859366 0.088598
0.914106 0.060329
0.955781 0.034767
0.983252 0.014475
0.996681 0.003017
0.995723 0.001324
0.978998 0.006589
0.947078 0.017319
0.901929 0.032747
0.845050 0.050036
0.778206 0.066056
0.703724 0.078681
0.624060 0.086495
0.541619 0.088665
0.458698 0.085029
0.377465 0.075897
0.299993 0.062006
0.228146 0.045015
0.163531 0.027286
0.107630 0.011286
0.061932 -0.000588
0.027877 -0.006029
0.006965 -0.003427
H.11 Sample contents of output file testdata for the default design
307
betal
60.000002
***** Fluid Flow Analysis Output *****
beta2 betainf
28.944236 48.806297
C1 inf
1.553013
x/1
0.000631
0.009873
0.035209
0.076335
0.132053
0.200460
0.278997
0.364701
0.454478
0.545205
0.633774
0.717286
0.793188
0.859366
0.914106
0.955781
0.983252
0.996681
0.995723
0.978998
0.947078
0.901929
0.845050
0.778206
0.703724
0.624060
0.541619
0.458698
0.377465
0.299993
0.228146
0.163531
0.107630
0.061932
0.027877
0.006965
Shockfree inlet angle *** outlet angle
63.71 29.16
ve~cl cpl
0.089072 0.992066
0.810870 0.342490
1.043871 -0.089666
1.172848 -0.375574
1.252750 -0.569383
1.292715 -0.671113
1.298880 -0.687089
1.280432 -0.639506
1.241971 -0.542493
1.182944 -0.399358
1.109494 -0.230976
1.029374 -0.059611
0.947414 0.102407
0.869248 0.244409
0.800752 0.358797
0.728572 0.469183
0.622611 0.612355
0.490643 0.759270
0.490643 0.759269
0.504801 0.745176
0.505936 0.744029
0.483908 0.765833
0.464630 0.784119
0.457655 0.790551
0.459038 0.789284
0.467292 0.781638
0.483094 0.766620
0.506257 0.743703
0.537967 0.710591
0.583639 0.659365
0.645510 0.583316
0.722467 0.478042
0.816200 0.333818
0.934111 0.127436
1.077991 -0.162066
1.020543 -0.041507
cp2
0.975698
1.014044
2.337798
3.213572
3.807236
4.118851
4.167787
4.022034
3.724869
3.286426
2.770651
2.245734
1.749451
1.314481
0.964094
0.625965
0.187410
0.262609
0.262609
0.219438
0.215924
0.282715
0.338727
0.358430
0.354547
0.331127
0.285125
0.214928
O. 113502
0.043412
0.276360
0.598830
1.040609
1.672785
2.559568
2.190282
308
Appendix H
***** Outlet Angle versus Inlet Angle *****
Betal Beta2
-80.000 23.137
-75.000 24.713
-70.000 25.499
-65.000 25.975
-60.000 26.299
-55.000 26.536
-50.000 26.720
-45.000 26.868
-40.000 26.993
-35.000 27.100
-30.000 27.195
-25.000 27.280
-20.000 27.359
- 15.000 27.432
- 10.000 27.503
-5.000 27.571
0.000 27.637
5.000 27.704
10.000 27.772
15.000 27.842
20.000 27.915
25.000 27.992
30.000 28.077
35.000 28.170
40.000 28.275
45.000 28.396
50.000 28.540
55.000 28.717
60.000 28.944
65.000 29.251
70.000 29.695
75.000 30.413
80.000 31.797
Appendix II I
'STACK'
A computer program for geometrical design
and analysis of turbomachine cascade blades
II1.1 Introduction and overview
STACK is a computer program for undertaking the geometrical design of turbo-
machine blade profiles or aerofoils based upon the method outlined in Chapter 2,
Section 2.4, Fig. 2.8. Blade profile coordinates are thus generated by superimposing
a 'base profile' thickness normal to a mean camber line which can be either a circular
arc or a parabola. In this respect it undertakes profile design tasks which are identical
to those of the flow analysis program CASCADE. On the other hand its functions
are entirely geometrical and its main role is that of blade stacking. In other words,
and as illustrated by Fig. III.1, the designer may specify several sections from hub
to casing of a turbomachine from his previous aerodynamic design work and stack
Fig.
II1.1 Output from program STACK
310 Appendix III
,, Profile Camber line Geometry Display Section Quit/save/DOS
* * * * * * * Section No. I * * * * * * *
Profile data are presently as
follows :-
Profile thickness is the C4 base profile
Profile
thickness scale
= t.0
Camber line type is circular
arc
x/l of maximum camber = 0.5
Camber angle = 0.0deg
Stagger angle = 0.0deg
Chord
length : t 00.0rams
Stacking line x = 0.0rams
Stacking line t, = 0.0rams
--: <: Press Air key and first
letter together to
grab a menu > >
.... e.g. AIt-T pulls
down the
Thermodynamics menu> >
Fig. 111.2 Main bar menu for program STACK
these on top of one another in some appropriate manner. For example, the five
sections shown here are stacked upon their centres of gravity so that in the case of
a rotor there would then be no centrifugal bending stresses. Section properties such
as area, centre of gravity, principal axes and second moments of area are calculated
for each section designed and recorded on file on exit from the program. Simple
instruction for getting started will now be given, including an introduction to the main
bar edit menu.
III.l.l How to run the program STACK
Before running the program STACK it is essential to have the file profiles available
in the current directory. This is the same file as that used for the program CASCADE
and contains a range of base profile thicknesses entered according to the format
presented in Section 11.9 of Appendix II. To run the program simply enter its name
stack
at the keyboard. The title page which then appears at the screen can be removed
by hitting any key, whereupon the main bar menu will be presented.
III.1.2 Main bar menu
Figure III.2 shows the main menu for STACK consisting of the top bar menu for
design and display, below which the current design data are recorded for the given
section, in this case Section No. 1. There are six keywords in the main bar menu
which enable the user to perform the following activities:
Profile To select the profile base thickness.
Camber line To select the camber angle and type of camber-line curvature.
Geometry To select profile stagger angle and scale and various options to
fix the blade stacking line.
111.3 The Geometry menu
311
Fig.
111.3 Profile geometry pull-down menus
Display
Section
Quit/save/DOS
For visual presentation of the single section during design or the
complete set of stacked profiles.
To select a given section for further design work or display out
of a possible total of eleven sections.
To enable the user to quit the session, to save the current work
or to exit to DOS.
We will now deal with these in more detail in the following sections.
111.2 Menus for editing blade profile geometry
The first two pull-down menus, shown in Fig. 111.3, enable the user to select the
profile shape, namely the base profile thickness and the camber line. To access these
simply enter Alt-P or Alt-C as instructed by the comment at the bottom of the screen.
Since the procedures involved in using these pull-down menus are identical to those
undertaken by the program CASCADE, no further instructions will be given here
and the reader is referred to Appendix II where full details have been presented.
The only significant difference is that of the first profile pull-down menu GEOMDATA
which enables the user to recover previous work from a file of that name. Further
comments about this will be made later in Section 111.6.
111.3 The Geometry menu
The third bar menu Geometry (Fig. 111.4) and its pull-down menus provide the
remaining tools for blade design which are as follows:
Stagger For setting the blade stagger angle A which will be +ve for a
compressor and _ve for a turbine.
312
Appendix III
Fig. 111.4 The Geometry pull-down menu
Chord
For choosing the blade chord length in mm.
x-y
axes
Shift x axis
Shift y axis
Tools for blade stacking.
Autostack
Stack on C of
G
The first two of these complete the design of the actual blade shape. The remainder
can then be used to shift the position of the blade profile in the
(x,y)
plane in a variety
of ways. Let us consider these in turn.
111.3.1 Completion of a blade design
To illustrate this we will begin by prescribing the basic blade profile parameters for
the five sections shown in Fig. III.1, which are shown in Table III.1.
Table
III.1 Example test case with five sections
Section Base Camber 0 ~ Stagger Chord l Location of
no. profile ;t ~ (mm) stacking line
Type Value
1 NACA0012 Circ. arc 70 40 100 C. of G.
2 NACA0012 Circ. arc 60 45 95 C. of G.
3 NACA0012 Circ. arc 50 50 90 C. of G.
4 NACA0012 Circ. arc 40 55 85 C. of G.
5 NACA0012 Circ. arc 30 60 80 C. of G.
111.3 The Geometry menu
313
Fig. 111.5 Section No 1 of test
case stacked
on the leading edge
First use the Profile menu to select the base profile NACA0012 in place of the
default profile C4. When making this selection the user is asked to specify the profile
thickness, which we will set here as 1.0. By entering some other value the base profile
may be thickened or thinned as required.
Next use the Camber line menu to select a camber angle of 700 ~ for 8ction No.
1 instead of the default value of 0 ~ We note from Fig. 111.3 that the default camber
line is already a circular arc, so that no change in that parameter is required.
Finally access the Geometry menu and then seleci Stagger from the pull-down menu
to reset the stagger angle to the required value for Section No. 1 of A = 40 ~ By using
the Display bar menu the outcome of these choices may be presented graphically at
the screen as shown by Fig. 111.5.
111.3.2 Tools for blade stacking
As can be seen from this example, any such new blade profile design will be stacked
on its leading edge unless subsequent use is made of the various stacking tools listed
in Section 111.3 and shown in Fig. 111.4. The first three of these pull-down menus
enable the user to reposition the
(x,y)
axes (menu x-y axes), or to shift them
independently (menus Shift x axis and Shift y axis), and the reader is invited to
experiment with these.
The pull-down menu Autostack, on the other hand, enables the designer to stack
the blade profile relative to position along and perpendicular to the chord line in
answer to the following questions presented on the screen:
x/chord for stacking line?--->
y/(max.camber)?--->
<enter value>
<enter value>