PENGUKURAN TURBULENSI DAN ANGULARITAS ALIRAN PADA TEROWONGAN ANGIN SUBSONIK LAPAN (THE MEASUREMENT OF TURBULENCE AND FLOW ANGULARITY IN LAPAN’S SUBSONIC WIND TUNNEL)
Abstract
This paper explains the measurement of turbulence intensity and angularity in LAPAN’s Open Loop Subsonic Wind Tunnel. The objective of the research is to find out the aerodynamic characterstic of the tunnel. Turbulence intensities were measured using 200 mm and 300 mm diameter turbulence sphere. The flow angularity in the cross section of tunnel’s test section was measured using five holes probe at two different axial position i.e. 1. above internal balance turning table and 2. above external balance turning table. The number of measured points are 110 for every cross section plane and the average velocity during angular flow measurement is 15 m/s. Turbulence measurements shows wind tunnel’s turbulence intensity of 0.26% at 25.9 m/s and 0.1% at 19 m/s. Angularity measurement shows relatively large angular flow variation in the jet, i.e. pitch angle of ±3o and achieving +7o at some locations and yaw angle of ±2.5o.
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Abstrak:
Makalah ini menjelaskan pengukuran intensitas turbulensi dan angularitas aliran pada seksi uji terowongan angin sirkuit terbuka kecepatan rendah Lembaga Penerbangan dan Antariksa Nasional. Tujuan dilakukannya pengukuran intensitas turbulensi dan angularitas adalah untuk mengetahui karakteristik aerodinamika terowongan angin kecepatan rendah LAPAN. Pengukuran intensitas turbulensi dilakukan menggunakan dua bola turbulensi (turbulence sphere) dengan diameter 200 mm dan 300 mm sedangkan pengukuran angularitas aliran dilakukan menggunakan probe 5 lubang pada bidang melintang di dua posisi aksial yaitu: di tengah roda putar internal balance dan di tengah roda putar external balance. Keseluruhan jumlah titik yang diukur per bidang adalah sebanyak 110 titik. Pengukuran dilakukan pada kecepatan rata-rata 15 m/s. Hasil pengukuran intensitas turbulensi menunjukkan bahwa intensitas turbulensi terowongan angin subsonik LAPAN pada kecepatan 25,9 m/s dan 19 m/s adalah sebesar 0,26% dan 0,1%. Hasil pengukuran angularitas aliran menunjukkan bahwa terowongan angin ini memiliki angularitas yang cukup besar yaitu sudut pitch ±3â° dengan beberapa titik mencapai +7â° dan sudut yaw ±2,5â°.
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