Experimental and numerical studies of pressure drop reduction in a 90° square elbow with the addition of circular turbulators

– Ducting system has two major components: straight ducts and fittings (sudden enlargement, sudden contraction, elbow, etc.). Pressure drop in the ducting system is caused mostly by friction loss, separation loss, and secondary flow. The aim of this study is to propose a method for reducing the pressure drop in the ducting system by installing a circular turbulator (CT) inside the 90° elbow. This research has been carried out experimentally and numerically with the test section consist of upstream duct, 90° square elbow with R/D_h=3, CT, and downstream duct. Experimental research has used a Pitot tube, an inclined manometer, and a pressure transducer. The research has been also conducted using turbulent simulation in 3D using the k-ɛ standard turbulence model. Reynolds number (Re_Dh) used has been 1.6×10⁴, 4.8×10⁴ and 9.5×10⁴ respectively based on hydraulic diameter. CT has been added inside the 90⁰ elbow with angular positions (α)=5°, 10°, 15°, 20°, respectively. The gap ratio and the diameter ratio of CT have been g/D_h=0.02 and d/D_h=0.1, respectively, where g is the gap between CT with the elbow wall and d is the diameter of CT. The results have showed that the addition of CT has been able to reduce the pressure drop on square duct with 90° elbow. The effect of CT at α = 15° and Reynolds number 4.8×10⁴ can reduce the overall pressure drop of the ducting system, about 22.14 % compared to ducting without CT.