Characterisation of the sound field emitted by an electric spark source in air
Résumé
Electrical sparks are used as sound sources in air to generate short duration (30 μs) spherical waves. Sources with small gap between the electrodes have been used as impulse sources to study the acoustical properties of scaled models of halls. Sources with larger gap are used to produce high pressure ( 1000 Pa) N-waves for nonlinear applications. Some of the present authors have recently studied theoretically and experimentally the characteristics of high pressure N-waves emitted from a 17 111111 gap spark source (1, 2]. These studies were dedicated to the dependance of the N-wave characteristics (maximum pressure, duration, rise time) with the propagation distance. However, the characteristics of the waves and the directivity of the source also depend 011 the electrode gap. I11 the present study, using 1 8 inch microphones, the field emitted by the spark source is studied experimentally for different electrode gaps (1-20 111111), propagation distances (0.15-1.5 111) and emission angles. Experimental data are compared to theoretical predictions. The influence of the limited frequency response of the microphones will be discussed. The present work is supported by the French International Program for Scientific Cooperation PICS and the French National Research Agency ANR S1MM1C project.