الفهرس 
EXPERIMENTAL SET-UPيوجد فقط 14 صفحة متاحة للعرض العام
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المستخلص
Experimental and theoretical study of finite amplitude oscillations in a straight circular constant cross –sectional area pipe with different circular bend connection at its exit, were studied. The different acoustic oscillation are created by a reciprocating piston at the one end of the circular straight pipe, while the other end is fitted with constant cross section area bend with different angles. Three different bend angles of 1350, 900, and 450 were used for experimental study. The pressure time histories along the constant cross-sectional area pipe were recorded at three different locations using a Piezo electric pressure transducers connected to a data acquisition system and DAQ VIEW software. The results showed that, the bend angle has a significant effect on wave deformation inside the duct. Also, it is observed that, at the pipe inlet, the free end duct (end pipe without bend) has larger acoustic wave amplitude than the same pipe fitted with the bend and vice versa at the duct exit exactly before the bend. Also, the amplitude of the wave at the duct inlet increases with increasing the bend angle from 450 to 1350, while it decreases at the duct exit exactly before the bend. That is due to the wave reflections from the bend at the straight pipe exit and wave interaction between different wave phases. Two different piston reciprocating speeds have been used and the results are compared with the different bend angles. The numerical results obtained without bend are compared with experimental one. It is shown that the experimental results are in a qualitative agreement with the numerical results within an accepted error .A fast Fourier transform is performed for the experimental results and higher harmonics are noticed in the pipe which fitted with bends at its exit. These higher harmonics are significantly noticed for duct fitted with 1350 bend. The results show that the geometry of variable angle constant cross-sectional area bend has a significant effect on a wave deformation .It notes that when the straight pipe end is free (without bend), the amplitude of acoustic wave (which created from reciprocating piston) is larger than the amplitude in the pipe which ended with a bend. The amplitude of the wave near the piston (when the bend with different angels were connected to the end of straight pipe) is smaller than the wave amplitude near piston in pipe without a bend case .But in case (when the bend with different angels were connected) the wave amplitude near to the bend connections is larger than that for the pipe without bend.