LDA-Measuring data: Flow over the backward facing step - variation of step angle.
*******************************************************************************************
Authors: B. Ruck und B. Makiola
Address:
Institute for Hydromechanics
Karlsruher Institute of Technology (KIT)
Kaiserstr. 12
76128 Karlsruhe
Germany
Tel.: (0721) 608-43897
e-mail:
ruck@kit.edu
Project: Ru 345/6
Targeted funding "Physics of separated flows", Februar 1992
Basic publication:
Ruck, B., Makiola, B.,1993: "The Flow over the Inclined Step", Notes on Numerical Fluid Mechanics, (Hrsg. Gersten), Vieweg-Verlag, Volume 40, pp. 47-55
Makiola, B., Ruck, B., 1993: "Flow Separation Over the Step with Inclined Walls, Near Wall Turbulent Flows, Launder, B.E., Speziale, C.G. (Eds.), Elsevier Press
Publication of extracts is permitted with indication of
source.
Data for expansion ratio 1.48
------------------------------------------------------------------------------
Explanation:
In this file you get the information about the file handling for the data files,
containing velocity data from LDA measurements behind a backward-facing step
flow with inclined step geometries.
Sketch of the investigated flow geometry:
y/H
|
|
|
==================================================================
Uo = max. inlet |
velocity |
--> flow direction |
|
h1 = inlet height |
====================\
| \
| \
| \
H = step height | \
| \
| step \
| angle alpha \ h2 = height behind the step
================================================================-----> x/H
negative <------| 0 |-----> positive
File name:
files with the extension *.mak are data files in which all measured
results for one step geometry and one Reynolds number are stored.
File-name-structure:
example: m15all.mak
The first letter "m" indicates the investigated step angle and
the expansion ratio ER according to the following table 1.
The number "15" indicates the Reynolds number divided by 1000
"all" indicates that the whole data set is complete
Table 1:
=====================================
|alpha | ER=1,48 | ER=2,0 |ER=3,27 |
=====================================
| 90 | M | O | Y |
|-----------------------------------|
| 45 | N | B | -- |
|-----------------------------------|
| 30 | H | P | -- |
|-----------------------------------|
| 25 | J | L | F |
|-----------------------------------|
| 20 | I | U | X |
|-----------------------------------|
| 15 | G | V | Z |
|-----------------------------------|
| 10 | K | R | -- |
=====================================
Streamwise velocity data for the following ("x") flow conditions
are available:
Table 2:
============================================================================
| Expansion |angle | Reynolds number (based on Uo and h1) |
| ratio ER |alpha | 5000 | 8000 | 11000 | 15000 | 33000 | 47000 | 64000 |
============================================================================
| (M )| 90 | x | x | x | x | - | x | x |
| (N )| 45 | x | - | - | x | - | x | - |
| (H )| 30 | x | x | x | x | - | x | - |
| 1.48 (J )| 25 | x | x | x | x | - | x | x |
| (I )| 20 | x | x | x | x | - | x | x |
| (G )| 15 | x | x | x | x | - | x | x |
| (K )| 10 | x | x | x | x | - | x | x |
============================================================================
| (O )| 90 | - | - | - | x | x | x | x |
| (B )| 45 | - | - | - | x | x | x | x |
| (P )| 30 | - | - | - | x | x | x | - |
| 2.00 (L )| 25 | - | - | - | x | - | x | x |
| (U )| 20 | - | - | - | x | - | x | x |
| (V )| 15 | - | - | - | x | - | x | x |
| (R )| 10 | - | - | - | x | - | x | x |
===========================================================================|
| (Y )| 90 | x | x | x | x | - | - | - |
| 3.27 (F )| 25 | x | x | x | x | - | - | - |
| (X )| 20 | x | x | x | x | - | - | - |
| (Z )| 15 | x | x | x | x | - | - | - |
===========================================================================|
Data-file-structure:
All data files ***.mak have a header, in which all important information
is stored. In the following example the header and the data-structure
are explained.
m15all.mak = Filename <--- file name
15000. = Reynolds-Zahl <--- Reynolds number based on max.
inlet velocity and inlet channel height
1.48 = Expansionsverhaeltnis ER <--- expansion ratio ER = h2/h1
12.00 = Stufenhoehe [mm] <--- step height H in mm
90.00 = Stufenwinkel <--- step angle alpha
8.69 = Uo [x/H=-2] Bezugsgeschwindigkeit <-- max. inlet velocity
2 step heights before the step edge in m/s
6.35 = Wiederanlegelaenge gemessen <--- measured reattachment
length, normalized with step height H
x/H y/H U/Uo rms/Uo psinorm <--- column indicator
----------------------------------------------------------------------------
-2.00 1.000 .000 .000 .0000
-2.00 1.042 .339 .136 .0041
-2.00 1.083 .595 .139 .0154
-2.00 1.167 .738 .113 .0476
-2.00 1.292 .837 .094 .1046
-2.00 1.417 .877 .087 .1668
-2.00 1.625 .934 .077 .2762
-2.00 1.833 .972 .056 .3914
-2.00 2.042 1.000 .053 .5105
-2.00 2.250 .978 .040 .6300
-2.00 2.458 .918 .061 .7446
-2.00 2.667 .846 .081 .8512
-2.00 2.792 .795 .081 .9106
-2.00 2.917 .716 .096 .9654
-2.00 3.083 .000 .000 1.0000
.00 1.000 .000 .000 .0000
.00 1.042 .185 .139 .0022
.00 1.083 .588 .142 .0116
.00 1.167 .739 .100 .0439
.00 1.292 .807 .084 .1002
.00 1.417 .871 .086 .1614
.00 1.625 .931 .070 .2708
.00 1.833 .978 .058 .3868
...
1. column (x/H): with the step height normalized streamwise channel
coordinate
2. column (y/H): with the step height normalized channel height
3. column (U/Uo): mean streamwise velocity (U), normalized with the max.
inlet velocity (Uo)
4. column (rms/Uo): rms-velocity (u'), normalized with the max. inlet
velocity (Uo)
5. column (psinorm): calculated values for the normalized stream function