MEASUREMENTS OF PRESSURE DISTRIBUTIONS ON A ROTOR BLADE USING PSP TECHNIQUES

Abstract

Surface pressure distributions on a rotating blade were measured by using pressure sensitive paint (PSP) to understand aerodynamic characteristics of a rotor blade. The present study was conducted to investigate the PSP techniques for measuring the pressure distributions on a rotor blade. In order to perform the experiment, the PSP was required to response very fast due to rapid pressure fluctuations on a rotor blade. High energy excitation light source was also needed to acquire proper intensity images in a short excitation time. The techniques were based on a lifetime method. Qualitative pressure distributions on an upper surface of small scale rotor in hovering condition were measured as a preliminary experiment prior to forward flight conditions in the KARI low speed wind tunnel laboratory. From measured pressure distributions, striking pressure gradient was observed on an upper surface of rotor blade and the resulting pressure showed expected gradient depending on different collective pitch angles.

ABSTRAK : Pengagihan tekanan permukaan ke atas berbilah putar disukat menggunakan cat sensitive tekanan (pressure sensitive paint (PSP)) untuk memahami sifat-sifat aerodinamik suatu berbilah putar. Kajian telah dijalankan untuk menyelidik teknik-teknik PSP dengan mengukur agihan tekanan ke atas suatu berbilah putar. Agar eksperimen dapat dijalankan dengan baik, PSP harus bertindak cepat kerana tekanan naik turun dengan pantas ke atas berbilah putar. Sumber cahaya ujaan tenaga tinggi diperlukan untuk mendapatkan imej keamatan wajar dalam jangka masa ujaan yang pendek. Teknik-teknik tersebut terhasil daripada kajian semasa hayat. Agihan tekanan kualitatif ke permukaan atas berskala kecil pemutar dalam keadaan mengapung diukur sebagai permulaan eksperimen, sebelum penerbangan kehadapan dalam makmal terowong angin laju rendah KARI. Daripada agihan tekanan yang disukat, kecerunan tekanan yang ketara diperolehi daripada permerhatian terhadap permukaan atas berbilah putar dan tekanan yang didapati menunjukkan tekanan kecerunan yang dijangka, bergantung kepada sudut himpunan anggul yang berbeza.