Planar Laser Induced Fluorescence of OH for Thermometry in a Flow Field Based on Two Temperature Point Calibration Method

Round 1

Reviewer 1 Report

 

The paper describes a two point calibration method based on the laser induced fluorescence technique used to determine the temperature in the combustion processes. The authors compare the results with ones obtained from the Raman spectroscopy and demonstrate an improvement of more than one order of magnitude. In my opinion the paper may be published in Applied Sciences after implementing the following suggestions.

In my opinion a few important details are missing in the paper.

1.       Please provide more detailed description of the PLIF setup (even a figure similar to Fig. 3 will be sufficient).

2.       The authors write that “the PLIF thermometry error in the temperature range of 1300–20 1800 K is reduced from 120 K using a single point calibration to 10 K 21 when the two point calibration method is used.” However, this sentence (or generally the authors findings) is not worth much without careful discussion of the uncertainty budget. The authors have to provide both the statistical and systematical uncertainties. E.g. if their total standard uncertainty is much bigger than 10 K than they should reconsider the conclusions.

3.       Please explain why these two particular OH transitions were chosen.

4.       Please provide suitable references in line 64 on page 2.

There are also some minor comments.

1.       Please expand the PLIF abbreviation in the abstract.

2.       Please provide definitions of ALL symbols used in the equations (e.g. A_J, a, b are not defined).

3.       Please provide the right units of velocity in line 117.

Author Response

Please see the attachment.

Author Response File: Author Response.docx

Reviewer 2 Report

The problem of detection oxygen-rich species, radicals, hot atoms in  flames and plasma is a wide field between technical physics and chemistry. The identifiation can be united with the temperature measurements and visualization of flames but in general it is better based on spectral parameters of chemical species formed under combustion/irradiation (IR, UV, luminescence parameters).

My only suggestion is to mention and discuss other papers (first of all having fundamental interest), whereby spectral characteristics of OH/O are analyzed (https://doi.org/10.1016/j.jlumin.2011.08.010).

 

Author Response

Related contents have been added.

The absorption wavelength, fluorescence emission wavelength, energy level distribution and the quenching intensity of different energy levels of OH is described in detail^[16-18], which provides the basic parameters for the measurement of OH fluorescence. The revised content is shown at line 49-53.

There have been two typical methods for eliminates the interference of fluorescence quenching. Cattolica excites different ground level to the Co-upper energy level and carries on the broadband measurement^[12], which effectively eliminates the interference of fluorescence absorption and fluorescence quenching to the double-line temperature measurement, but the difference of ground state energy level is limited when the Co-upper energy level is excited, and the sensitivity range of this method is limited to the low temperature area of combustion field. Devillers discusses in detail the selection of excitation line and single point calibration method of double-line PLIF temperature measurement^[19]. By comparing the results of temperature measurement of different excitation lines, the excitation line with less interference by quenching is obtained, but the selection result is limited to certain parameter flow field. The revised content is shown at line 96-110.

Reviewer 3 Report

Abstract

Add recommendations for future research that can be done or the benefits that can be obtained from the results of research that has been done

 

Introduction

The novelty of the research needs to be sharpened again with the following inputs:

1.     Add to the previous research on calibration method, state the advantages and disadvantages so that it was decided to use two temperature point

 

Method

1.     Please add the air-fuel ratio of CH4 and Air

2.     Please add the equation of standard deviation

 

Result

1.     Please describe the temperature range of the unburned zone, the reaction zone, and the burnout zone

 

2.     Please present comparison results of optimized two-point calibration and single calibration point with the standard deviation result calculation

Comments for author File: Comments.pdf

Author Response

Please see the attachment.

Author Response File: Author Response.docx