Effect of Transverse Acoustic Flow on the Input Impedance of Rapidly Flaring Horns

• Autorzy: Nederveen C. J.
• Języki publikacji: EN

Abstrakty

EN

In slowly flaring horns the wave fronts can be considered approximately plane and the input impedance can be calculated with the transmission line method (short cones in series). In a rapidly flaring horn the kinetic energy of transverse flow adds to the local inertance, resulting in an effective increase in length when it is located in a pressure node. For low frequencies corrections are available. These fail at higher frequencies when cross-dimensions become comparable to the wavelength, causing resonances in the cross-direction. To investigate this, the pipe radiating in outer space is modelled with a finite difference method. The outer boundaries must be fully absorbing as the walls of an anechoic chamber. To achieve this, Berenger’s perfectly matched layer technique is applied. Results are presented for conical horns, they are compared with earlier published investigations on flanges. The input impedance changes when the largest cross-dimension (outer diameter of flange or diameter of the horn end) becomes comparable to half a wavelength. This effect shifts the position of higher modes in the pipe, influencing the conditions for mode locking, important for ease of playing, dynamic range and sound quality.

Słowa kluczowe

EN

input impedance; horn; wind musical instruments; boundary conditions

• Wydawca: Instytut Podstawowych Problemów Techniki PAN ; Komitet Akustyki PAN ; Polskie Towarzystwo Akustyczne
• Czasopismo: Archives of Acoustics
• Rocznik: 2011
• Tom: Vol. 36, No. 3
• Strony: 533--544
• Opis fizyczny: Bibliogr. 6 poz., tab., wykr.

Twórcy

autor

Nederveen C. J.

• Acacialaan 20 2641 AC Pijnacker, The Netherlands,

Bibliografia

• 1. Berenger J.P. (1994), A perfectly matched layer for the absorption of electromagnetic waves, J. Computational Physics, 114, 1, 185-200.
• 2. Dalmont J.-P., Nederveen C.J., Joly N. (2001), Radiation impedance of tubes with different flanges: numerical and experimental investigations, J. Sound and Vibration, 244, 3, 505-534.
• 3. Nederveen C.J. (1998), Acoustical Aspects of woodwind instruments, 2nd edition, Northern Illinois University Press, De Kalb, Ill, 78-79.
• 4. Nederveen C.J., Dalmont J.-P. (2008), Corrections to the Plane-Wave Approximation in Rapidly Flaring Horns, Acta Acustica/Acustica, 94, 3, 461-473.
• 5. Taflove A., Hagness S.C. (2005), Computational Electrodynamics, Artech House, Norwood, 273-328.
• 6. Yuan X., Borup D., Wiskin J.W., Berggren M., Eidend R., Johnson S.A. (1997), Formulation and validation of Berenger's PML absorbing boundary for the FDTD simulation of acoustic scattering, IEEE Transactions on Ultrasonics, Ferroelectrics, and Frequency Control, 44, 4, 816-822.