Study of flow induced noise in rectangular test sections with an obstruction

مقدم أطروحة جامعية

Rashid, Haydar Kurdi

الجامعة

الجامعة التكنولوجية

الكلية

-

القسم الأكاديمي

قسم الهندسة الكهروميكانيكية

دولة الجامعة

العراق

الدرجة العلمية

دكتوراه

تاريخ الدرجة العلمية

2009

الملخص الإنجليزي

The aerodynamic noise induced by flow inside two subsonic wind tunnels with an obstruction was investigated.

First wind tunnel has flow speed 12, 2 m / s, and the dimensions of test section are (0.5 m x 0.305m x 0.305m).The second subsonic wind tunnel operate with flow speed 23.7 m/s, and the dimensions of test section are (0.96 m x 0.47m x 0.47m). Experimental work was done on first wind tunnel with an airfoil NACA 0015 and on the second wind tunnel with an airfoil NACA 0012.The airfoil NACA 23015 was used in both wind tunnels to compare between the aerodynamic results and noise effect.

The aerodynamic sound generation from flow inside the first wind tunnel and around the airfoil NACA 0015 at angles of attack (0°, 8°, 10°, 16°, 20°) was displayed using computer software connected to condenser microphone.

Also, the sound generation from flow inside the second wind tunnel and around the airfoil NACA 0012 at angles of attack (0°, 5°, 10°, 20°, 30°) was displayed using the same computer software that connected to same condenser microphone.

The vibration of the test section for each wind tunnel was measured by using digital vibration meter.

The whole sound generation in each wind tunnel was recorded for each angle of attack, and re-played without flow in each wind tunnel and then the vibration of the test section was measured.

The airfoil NACA 23015 was used in both wind tunnel, at the same angles of attack (0°, 8°, 16°, 20°, 30°).

The sound generation in both wind tunnels was displayed using the same procedure that used on airfoil NACA 0015 or on airfoil NACA 00l2.The aerodynamic characteristic of three airfoils for each angle of attack were measured and analyzed. The acoustic wave propagation in each test section was modeled.

Two mathematical models were built for acoustic pressure propagation and particle velocity distribution.

Numerical solution was done to produce the sound pressure propagation and distribution along the wind tunnel test section in one and two-dimensional flows using Leapfrog method.

The aerodynamic characteristic was compared with the measured sound generation and propagation behavior and vibration results for each case.

ANSVS (11) is also used to examine the effect of the natural frequency for second wind tunnel (test section and diffuser) and airfoil NACA 0012 on the frequency of sound generation.

Three cases were taken for airfoil NACA 0012 at angles of attack (0°, 10°, 30°). The results indicated that the sound generation for each airfoil relation with aerodynamic characteristic for this airfoil.

For the first wind tunnel and airfoil NACA 0015 the maximum noise occur at angle of attack 10° at the center of wind tunnel but, for second wind tunnel and airfoil NACA 0012 the maximum noise occur at center with angle of attack 30°.

Inside the first wind tunnel which has flow speed 12.2 m / s with airfoil NACA 23015 the maximum noise amplitude occur at angle of attack 0° and for the second wind tunnel which has flow speed 23.7 m / s the maximum noise amplitude occur at angle of attack 30°.

The natural frequency for the second wind tunnel very low and start from (19) Hz to (86) Hz while the natural frequency for airfoil NACA 0012 is very high compare with the natural frequency of the second wind tunnel and its range is (34-2200) Hz, The angles of attack for the NACA 0012 have low effect on its natural frequency.

التخصصات الرئيسية

هندسة الميكاترونكس

الموضوعات

• الضوضاء
• ديناميكا الموائع

• APA
• MLA
• AMA

لغة النص

الإنجليزية

نوع البيانات

رسائل جامعية

رقم السجل

BIM-305064