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Implementation of Pressure Sensitive Paint (PSP)Method for Pressure Distribution Measurement

Ahmadi, Farhad | 2023

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  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 56374 (45)
  4. University: Sharif University of Technology
  5. Department: Aerospace Engineering
  6. Advisor(s): Kebriaei, Azadeh
  7. Abstract:
  8. Quantitative measurement of pressure on surfaces in wind tunnels and flight tests is essential to understand the aerodynamic performance of flying vehicles. Pressure data are also essential for validation and verification of computational fluid dynamics codes. One of the relatively new methods of measuring pressure distribution on aerodynamic surfaces is the method of pressure sensitive paint (PSP). The PSP method is an optical technique that can measure the pressure distribution on the surface without using common pressure sensors or transducers, with greater spatial resolution and lower cost. This method has a unique ability for non-contact (non-interfering) measurements. In this method, each pixel of the camera acts as a pressure sensor, so a continuous distribution of pressure on the painted surface is obtained. To implement this technique, the composition of the paint that has fluorescence property is first determined, and after spraying it on the surface, its calibration will be done in a chamber with the ability to adjust the pressure and temperature, so its Stern-Volmer diagram will be extracted. For this purpose, a calibration chamber was made and all parts of it explained. One of the challenges of this method was the low adhesion of paint on aluminum surface. So that when placed in front of the air jet, with the increase in wind speed, this paint was separated from the surface. For deal with problem, six aluminum samples with different surface preparation method were performed. These techniques include acetone cleaning of the sample, hard anodizing, etching, submerging the sample in an alkaline solution, sandblasting, and wet-blasting of the aluminum. The adhesion of PSP paint on those applied methods was checked by conducting a pull-off test, and the wet-blast method was introduced as the best preparation method with the highest paint adhesion. When compared to the sample without surface pretreatment, the wet-blasted sample's adhesion improved dramatically by more than ten times. Finally, the pressure distribution at the stagnation point due to the collision of the air jet on the surface was determined using the PSP method
  9. Keywords:
  10. Stagnation Point ; Pressure Sensitive Paint (PSP) ; Optical Pressure Distribution Determination Method ; Stern-Volmer Diagram ; Surface Preparation

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