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Electroacoustical systems in rooms
Published in Heinrich Kuttruff, Room Acoustics, 2016
Another type of loudspeaker which is used in many sound reinforcement systems is the horn loudspeaker. It consists of a tube with continuously increasing cross-sectional area, called a horn, and an electrodynamic driver attached to the horn at its narrow end. The main advantage of this loudspeaker is its high-power efficiency because the horn improves the acoustical match between the driver’s diaphragm and the free field. This effect is usually augmented by a pressure chamber incorporated in the driver acting as a mechanical impedance transformer (see Figure 10.5). Another advantage of the horn loudspeaker is that it has a certain directivity even at low frequencies. The simplest horn types are the conical and the exponential horn. Unfortunately, no closed formulae are available for calculating or estimating the directional characteristics of a horn loudspeaker which depends on the shape and the length of the horn as well as the size and the shape of its ‘mouth’. Thus, the directional pattern of a horn has to be determined experimentally or with numerical methods. The same holds for its frequency characteristics. The most successful way to do this is by application of the boundary element method (BEM), which has been mentioned in Section 3.5. By combining several horns a wide variety of directional patterns can be achieved. The most straightforward solution of this kind are the multicellular horns consisting of many single horns, the openings of which approximate a portion of a sphere and yield nearly uniform radiation into the solid angle subtended by the opening of the horn.
Practical Antenna Systems
Published in Jerry C. Whitaker, The RF Transmission Systems Handbook, 2017
The horn antenna may be considered a natural extension of the dominant-mode waveguide feeding the horn in a manner similar to the wire antenna, which is a natural extension of the two-wire transmission line. The most common types of horns are the E-plane sectoral, H-plane sectoral, pyramidal horn (formed by expanding the walls of the TE0,1-mode-fed rectangular waveguide), and the conical horn (formed by expanding the walls of the TE1,1-mode-fed circular waveguide). Dielectric-loaded waveguides and horns offer improved pattern performance over unloaded horns. Ridged and tapered horn designs improve the bandwidth characteristics. Horn antennas are available in single and dual polarized configurations.
Ultrasonic Vibration-Assisted Sintering
Published in Rupinder Singh, J. Paulo Davim, Non-Conventional Hybrid Machining Processes, 2020
Gurminder Singh, Pulak M. Pandey
The horn is used to amplify the amplitude of the ultrasonic waves. The most important part in developing an ultrasonic system is to design the ultrasonic horn. The resonance between the horn and the transducer transfers the waves from one end to another end. Generally, the horns can be designed in three shapes: step, exponential, and conical [36]. These shapes have their own merits and demerits. The design selection of horn shape depends upon the application requirements. The step horn shape has a high magnification factor [37]. On the other hand, the exponential shape is used where less stress concentration is required [38]. The conical shape is generally used to fabricate small horns [39]. The schematic and magnification factors of these horns are shown in Figure 1.2. Generally, three types of alloy materials are used to fabricate horn, namely, aluminum alloy, stainless steel alloy, and titanium alloy [36]. The selection of the materials depends upon the application requirements and is also concerned with the cost of the setup. Sometimes, cylindrical shape horn is used for the displacement transmission. In that case, a booster is used to amplify the amplitude, which is transferred by the horn. The design of the horn is done by two methods: analytical and computational. Several authors [36,40–44] have used these methods for the horn design, which are described in detail in the literature. First, the length of the horn is calculated by the analytical calculations. Further, the minor changes in length are done by using FEM (finite element method) to obtain the required natural frequency. The modal analysis is used to find out the mode shape and natural frequency [45]. Furthermore, at the obtained natural frequency, the harmonic analysis is carried out to check the amplitude of displacement at the other end of the designed horn [46].
Design of wide ultrasonic horns based on topology optimization
Published in Engineering Optimization, 2022
Mehran Afshari, Behrooz Arezoo
Ultrasonics is a branch of acoustics concerned with the generation and utilization of inaudible acoustic waves (Gallego-Juárez and Graff 2014). Ultrasonic waves are used in a variety of fields, such as welding, machining, cutting and sonochemistry (Abramov 2019; Ensminger and Bond 2011). Different equipment, such as ultrasonic generators, transducers and horns, is needed to apply ultrasonic waves in different processes. The horn is an essential element of an ultrasonic process. It vibrates at high frequencies and longitudinal mode and transfers ultrasonic waves provided by the transducer. Horns are categorized into two types. Slender horns are those with lateral dimensions lower than one-fifth of the wavelength in that specific material. In these horns, the effect of Poisson’s ratio is ignored. Wide horns are those where, at least in one direction, the lateral dimensions are greater than one-fifth of the wavelength. In wide horns, the Poisson’s ratio effect cannot be ignored. In these horns, the output face of the horn vibrates non-uniformly owing to the effect of Poisson’s ratio. Therefore, these horns should be designed in such a way that their output face vibrates uniformly (Derks 1984; Ensminger and Stulen 2008; Rozenberg 2013; Troughton 2008).
Machinability analysis of Titanium 64 using ultrasonic vibration and vegetable oil
Published in Materials and Manufacturing Processes, 2022
Jay Airao, Chandrakant K. Nirala
An indigenously developed ultrasonic assisted turning setup is utilized for experiments, as presented in Fig. 1. The setup consists of a horn, transducers, a frequency generator, and an insert. A 230 V, 50 Hz, AC supply is given as an input to the frequency generator, converting it into a 20 kHz, low voltage signal. The electrical signal is then transformed to mechanical displacement using a piezoelectric transducer. The horn acts as a guiding media to provide the displacement to the tool bolted toward the end. The length and the diameter are the critical parameters for designing the horn. During the design of the horn, the diameter and length are chosen based on the resonance frequency. The material used for the horn is Al 7075.
Analytical and numerical investigations of the ultrasonic microprobe considering size effects
Published in Mechanics of Advanced Materials and Structures, 2020
A. Hosseini, M. Rahaeifard, M. Mojahedi
Horns are named after the changes in their cross section area. The most used horns in industries are stepped, exponential, catenoidal, rectangular, and barbell ones. Probe’s applications can be classified into macro and micro-scale. Some applications in macro scale are ultrasonic welding, ultrasonic cutting, ultrasonic soldering, etc. In micro-scale due to their small size, microprobes have special applications in the field of biomedical sciences. Microprobes can be utilized in the recording of cardiac signals, measuring the blood viscosity, brain and eye surgeries, and manufacturing of ultrasonic surgery knife.