A Dipping Duration Study for Optimization of Anodized-Aluminum Pressure-Sensitive Paint

Anodized-aluminum pressure-sensitive paint (AA-PSP) uses the dipping deposition method to apply a luminophore on a porous anodized-aluminum surface. We study the dipping duration, one of the parameters of the dipping deposition related to the characterization of AA-PSP. The dipping duration was varied from 1 to 100,000 s. The properties characterized are the pressure sensitivity, temperature dependency, and signal level. The maximum pressure sensitivity of 65% is obtained at the dipping duration of 100 s, the minimum temperature dependency is obtained at the duration of 1 s, and the maximum signal level is obtained at the duration of 1,000 s, respectively. Among the characteristics, the dipping duration most influences the signal level. The change in the signal level is a factor of 8.4. By introducing a weight coefficient, an optimum dipping duration can be determined. Among all the dipping parameters, such as the dipping duration, dipping solvent, and luminophore concentration, the pressure sensitivity and signal level are most influenced by the dipping solvent

Optimization of Anodized-Aluminum Pressure-Sensitive Paint by Controlling Luminophore Concentration

Anodized-aluminum pressure-sensitive paint (AA-PSP) has been used as a global pressure sensor for unsteady flow measurements. We use a dipping deposition method to apply a luminophore on a porous anodized-aluminum surface, controlling the luminophore concentration of the dipping method to optimize AA-PSP characteristics. The concentration is varied from 0.001 to 10 mM. Characterizations include the pressure sensitivity, the temperature dependency, and the signal level. The pressure sensitivity shows around 60 % at a lower concentration up to 0.1 mM. Above this concentration, the sensitivity reduces to a half. The temperature dependency becomes more than a half by setting the luminophore concentration from 0.001 to 10 mM. There is 3.6-fold change in the signal level by varying the concentration. To discuss an optimum concentration, a weight coefficient is introduced. We can arbitrarily change the coefficients to create an optimized AA-PSP for our sensing purposes

Characterization and Optimization of Polymer-Ceramic Pressure-Sensitive Paint by Controlling Polymer Content

A pressure-sensitive paint (PSP) with fast response characteristics that can be sprayed on a test article is studied. This PSP consists of a polymer for spraying and a porous particle for providing the fast response. We controlled the polymer content (%) from 10 to 90% to study its effects on PSP characteristics: the signal level, pressure sensitivity, temperature dependency, and time response. The signal level and temperature dependency shows a peak in the polymer content around 50 to 70%. The pressure sensitivity was fairly constant in the range between 0.8 and 0.9 %/kPa. The time response is improved by lowering the polymer content. The variation of the time response is shown to be on the order of milliseconds to ten seconds. A weight coefficient is introduced to optimize the resultant PSPs. By setting the weight coefficient, we can optimize the PSP for sensing purposes

Global Oxygen Detection in Water Using Luminescent Probe on Anodized Aluminum

We have developed anodized-aluminum pressure-sensitive paint (AA-PSP) as a global oxygen sensor in water. Platinum (II) meso-tetra(pentafluorophenyl)porphine is selected as a luminophore based on a dipping deposition study. The developed AA-PSP is characterized using water calibration setup by controlling dissolved oxygen concentration. It is shown that AA-PSP yields 4.0% change in luminescence per 1 mg/L of oxygen concentration at 23°C. Other characteristics, such as temperature dependency, photo-degradation, and physical stability, are discussed in this paper. This AA-PSP is used to demonstrate its capability of global oxygen detection in water using the impingement of oxygen rich water (20 mg/L). Even though the difference in water is only the concentration of oxygen, we can obtain global oxygen information of the jet impingement using a fast frame rate camera. Oxygen maps as well as cross-sectional distributions are shown every 0.1 s

Round-robin study for ice adhesion tests

Ice adhesion tests are widely used to assess the performance of potential icephobic surfaces and coatings. A great variety of test designs have been developed and used over the past decades due to the lack of formal standards for these types of tests. In many cases, the aim of the research was not only to determine ice adhesion values, but also to understand the key surface properties correlated to low ice adhesion surfaces. Data from different measurement techniques had low correspondence between the results: Values varied by orders of magnitude and showed different relative relationships to one another. This study sought to provide a broad comparison of ice adhesion testing approaches by conducting different ice adhesion tests with identical test surfaces. A total of 15 test facilities participated in this round-robin study, and the results of 13 partners are summarized in this paper. For the test series, ice types (impact and static) as well as test parameters were harmonized to minimize the deviations between the test setups. Our findings are presented in this paper, and the ice- and test-specific results are discussed. This study can improve our understanding of test results and support the standardization process for ice adhesion strength measurements

Anodized aluminum pressure sensitive paint for unsteady aerodynamic applications

A comprehensive study of anodized aluminum pressure sensitive paint (AA-PSP) is documented. The study consisted of the development of AA-PSP and its application to unsteady aerodynamic fields at atmospheric conditions. Luminophore application mechanism and two-component application on anodized aluminum was studied for the development. Two-component application includes hydrophobic-coated AA-PSP and bi-luminophore system. It was found that the polarity of solvents and the surface charge of anodized aluminum determine the optimized luminophore application. As a result, a wide variation of luminophore can be applied on anodized aluminum. To apply both components on anodized aluminum, optimum solvent polarities for each component should match. AA-PSP performances, such as pressure sensitivity, temperature dependency, signal level, and aging were improved by the luminophore application mechanism and two-component application. AA-PSPs demonstrate the capability of measuring surface pressures on unsteady aerodynamic fields. For an application to the Purdue Mach 4 Quiet Flow Ludwieg Tube, surface pressures on the order of a hundred Pascals were measured for approximately 200ms. The measurement uncertainty of the pressure was on the order of 5%. The main uncertainty source comes from fitting the adsorption control model to calibration points. The results compared qualitatively well to CFD calculations. A miniature fluidic oscillator was used to demonstrate the capability of measuring oscillating unsteady aerodynamic fields with 6.4kHz primary frequency. Flow oscillation images as well as pressure maps of various phases were captured by AA-PSP with PtTFPP as a luminophore (AA-PSPPtTFPP ). Main uncertainty source comes from fitting the adsorption control model to calibration points and from the pulse width of illumination. The measurement uncertainty of the pressure was 4.68%. AA-PSPPtTFPP was applied to a high-amplified acoustic fielding in a standing wave tube. The maximum pressure change created was 171dB (1.04psi). Sinusoidal pressure wave images inside a standing wave tube were captured at various phases. From these images, the integrated pressure map was obtained. In this case, measurement uncertainty was 3.64% and was due mainly to the pulse width and from fitting of the adsorption controlled model. Comparison with theoretical model is necessary to validate the integrated map as a streaming pattern

Special Issue: Deicing and Anti-Icing of Aircrafts

In-flight icing for aircrafts is a large concern for all those involved in aircraft operations [...