STEP-BY-STEP INSTRUCTION FOR EXAMPLE 2

 

A pair of PIV recordings, which is one example out of several thousand PIV recordings recorded by Kaehler (2001) in DLR within the EC funded EUROWAKE project dedicated to the investigation of wake vortices behind a transport aircraft, is used here to demonstrate the procedures for evaluating a single-exposed PIV recording pair with the EDPIV software. The measurement was conducted at 1.64 m behind the wing tip, and the field of view of 170-mm x 140-mm was imaged with a digital resolution of 1280x1024 pixels. An evaluation procedure is suggested as follows.

 

Step 1: Load digital PIV recording pair

- Execute file “Edpiv.exe” - The start window is shown on the screen;

- Select menu “File \ Open recording 1” to open “…\ PIVsamples \ 2_SingleExposedPair \ A001_1.bmp”;

- Select menu “File \ Open recording 2” to open “…\ PIVsamples \ 2_SingleExposedPair \ A001_2.bmp”.

Step 2: Input imaging scale and time interval

- Click menu “Edit / Scale & time” in the start window to open dialogue box “Imaging scale / time interval”;

- Select radio button mm;

- Input 170 in edit box “Reading on ruler”;

- Input 1280 in edit box “Corresponding pixels”;

- Input 20 in edit box “Time interval [mu-s]”;

- Press “OK” button to return to start window.

Step 3: Set up evaluation parameters

- Click menu “Edit / Evaluation settings” in the start window to open the “Evaluation settings” window;

- Set up parameters as follows
Method & algorithm:
PIV
Ellipse window: Selected
Recording type:
Single recording (pair)
Exposure type:
Single
Flow type:
One phase
Initial window shift:
(X,Y), X=0, Y=0
Interrogation grid:
16x16
Error limits:
Dx=3, Dy=3
Iteration number:
0 (Initial), 6 (Final) 
Window width :
32 (Initial), 32 (Final)
Window height :
32 (Initial), 32 (Final)
Search radius:
12

- Close “Evaluation settings” window.

Step 4: Evaluate the PIV recording pair

- Press button “Evaluation” in the start window;

- Click menu “Start” in “Evaluation” window;

- Answer “Yes” to question “Do you want to start an evaluation?”

- Wait until the evaluation is completed;

- Press button “OK” to close the dialogue box that notices the end of the evaluation.

Step 5: Save evaluation result

- Click menu “Edit \ Accept results \  valid + corrected” to accept valid and corrected displacement vectors;

- Click menu “File \ Save data” - Dialogue box “Save evaluation results” appears;

- Find a desired folder, type in a file name in the dialogue box;

- Press button “Save” to complete the saving procedure.

Step 6: Plot vector map

- Close EDPIV;

- Use TECPLOT to make plots.