Comparison of Lifetime-Based Pressure-Sensitive Paint Measurements in a Wind Tunnel Using Model Pitch–Traverse and Pitch–Pause Modes
Round 1
Reviewer 1 Report
Comments and Suggestions for Authors
Very interesting paper and well conducted research. I got few minor questions:
1. As I understood in Introduction You claim that your methodology is in line with procedure given in [7]. The description of your procedure, especially in pitch-traverse experiments, is not in line with quoted paper – for me it more resembles the standard two gate method. Could you elaborate on this in text?
2. Please describe the PSP pressure image mapping on 3D in more details. How this procedure is implemented or give a reference with the same model (DLR-F22)
3. Please describe in detail the a-priori calibration procedure
4. How on-chip accumulation is performed in pitch-traverse measurements?
Comments on the Quality of English Language
Good English, just slight polishing is necessary. For example repertition of wind tunnel two times in the same sentence.
"In order to improve the data productivity of a wind tunnel test, the model under investi-9 gation in the wind tunnel is moved continuously with a predetermined constant angular speed in 10 the so-called pitch-traverse mode"
Author Response
Dear reviewer,
Thank you for your assessment and helpful comments, which have helped us improve our manuscript. We have addressed your inquiries and comments and made changes to our manuscript, which are marked in red text. Below we provide details for each comment.
Best regards, Christian Klein
Author Response File: 
Author Response.pdf
Reviewer 2 Report
Comments and Suggestions for Authors
This study verifies the application of lifetime-based PSP utilizing on-chip accumulation with a continuously moving wind tunnel model. Comments are as below.
1. lines 262-263: The statement "The alternating gate acquisition has the advantage of reducing the influence of temperature change and photodegradation during the test." is ambiguous. No data or reference supports this statement.
2. line 310: A priori calibration was conducted. However, no calibration data is presented, including pressure and temperature sensitivity.
3. lines 454-455: Data acquisition using the conventional pressure taps did not take place in the measurement campaign presented here. Therefore, the statement in lines 224-225 (with multiple pressure port sections S1, S2, S3, S4, S5, S6 for conventional steady pressure measurements) can be deleted.
4. For a blowdown transonic wind tunnel, there is is a temperature drop during the tests. In addition, the formation of vortices and a separation bubble would affect the surface temperature which induces the uncertainty in the PSP measurements. However, no temperature correction is presented in this submission.
Author Response
Dear reviewer,
Thank you for your assessment and helpful comments, which have helped us improve our manuscript. We have addressed your inquiries and comments and made changes to our manuscript, which are marked in red text. Below we provide details for each comment.
Best regards, Christian Klein
Author Response File: Author Response.pdf
Round 2
Reviewer 2 Report
Comments and Suggestions for Authors
The authors addressed all the comments by the reviewer. The revision is acceptable to be published in Photonics.
