Sound Intensity Distribution Around Organ Pipe

Abstract

The aim of the paper was to compare acoustic field around the open and stopped organ pipes. The wooden organ pipe was located in the anechoic chamber and activated with a constant air flow, produced by an external air-compressor. Thus, a long-term steady state response was possible to obtain. Multichannel acoustic vector sensor was used to measure the sound intensity distribution of radiated acoustic energy. Measurements have been carried out on a defined fixed grid of points. A specialized Cartesian robot allowed for a precise positioning of the acoustic probe. The resulted data were processed in order to obtain and visualize the sound intensity distribution around the pipe, taking into account the type of the organ pipe, frequency of the generated sound, the sound pressure level and the direction of acoustic energy propagation. For the open pipe, an additional sound source was identified at the top of the pipe. In this case, the streamlines in front of the pipe are propagated horizontally and in a greater distance than in a case of the stopped pipe, moreover they are directed downwards. For the stopped pipe, the streamlines of the acoustic flow were directed upwards. The results for both pipe types were compared and discussed in the paper.

The Dependence of Flue Pipe Airflow Parameters on the Proximity of an Obstacle to the Pipe’s Mouth

“…The influence of the obstacle proximity on the sound parameters is often omitted in research. e.g., Odya et al [ 10 ], while carrying out the measurements in the set of pipes, did not consider the too close position of the pipes to each other, which could have a significant influence on the results presented in that paper.…”

“…To determine the dependence of some intervals on others we used the natural interval extension, consisting of the same operations as the real-valued function from Equation (9). Additionally, to verify the obtained results, the function h z as the centered form of the inclusion function of h was used [22], satisfying Equation (10).…”

“…, where z ∈ y (10) where: y is the interval, z is the middle point of y interval, ∇h(y) is a derivative of h(y) function.…”

“…The state-of-the-art research in the area of sound generation in organ pipes raises various aspects, e.g., airflow analysis [ 4 , 5 , 6 ], or transient state in the process of sound initiation [ 7 , 8 , 9 ]. The experiments and simulations of sound formation in pipes are reported in literature as well [ 10 , 11 , 12 ]. There are also works in the field of the acoustics of resonators [ 13 , 14 , 15 ].…”

Modeling and simulation of a pipeline leak detection using smart inspection ball

“…According to the experiments, attenuation was found to have the most significant effect on the propagation of the acoustic waves that are utilized for impact detection. Odya et al [31] investigated the movement of sound waves through organ pipes using a method that evaluated the intensity of the sound. Previous researchers collected the sound intensity distributions everywhere around the pipes and illustrated how acoustic energy was traveling.…”