日本音響学会誌
Online ISSN : 2432-2040
Print ISSN : 0369-4232
25 巻, 4 号
選択された号の論文の9件中1~9を表示しています
  • 粟屋 潔
    原稿種別: 本文
    1969 年 25 巻 4 号 p. 175-176
    発行日: 1969/07/20
    公開日: 2017/06/02
    ジャーナル フリー
  • 永田 穂
    原稿種別: 本文
    1969 年 25 巻 4 号 p. 177-193
    発行日: 1969/07/20
    公開日: 2017/06/02
    ジャーナル フリー
  • 飯沼 元
    原稿種別: 本文
    1969 年 25 巻 4 号 p. 194-198
    発行日: 1969/07/20
    公開日: 2017/06/02
    ジャーナル フリー
    Acoustic wave energy once radiated into a bulk of fluid contained in a tank, is finally converted into heat gained by the fluid, with conversion efficiency nearly 100%, after traveling throughout the bulk by undergoing successive perfect reflection at its boundary. It would therefore be possible to determine calorimetrically the total acoustic power existing in the fluid by a simple measurement of the time rate of heat generation (i. e. the rate of temperature-rise) within the fluid. Although the accuracy of this determination procedure was proved to be good in many physical laboratories, the method has never been applied extensively to practical ultrasonic equipment such as cleaning tank. The reason for this appears to lie in that some fundamental precautions are called for from the standpoint of physical experiment on heat, in order to carry out accurate experimentation. The present paper describes the essential precautions needed in the calorimetric determination of acoustic power and also shows that correct results were actually obtained with these precautions on experimenting on some practical cleaning tanks. Fig. 1 shows our simple and general arrangement for the measurement. One ordinary glass-rod thermometer together with a metal gauze protection against strong sonic field is the only essential measuring tool, because the bath becomes equitemperature owing to the natural agitation caused by ultrasonic streaming. Minimization of evaporation heat loss is also necessary to carry out accurate experiment and this problem was ingeniously solved by covering the water surface by a floating sheet of paper heavily wetted with machine oil. The present method gives the accurate total acoustic power, so far as heat generation within the transducers themselves is negligible. Fig. 2(A) and 2(B) show the results of the experiments we carried out on Tank A transducerized with 3 bariumtitanate vibrators and on Tank B with 6 vibrators, giving the measured total acoustic powers of 43. 4W and 97W respectively. These values are in good agreement with the measured electrical input powers. Fig. 3 shows another experiment on Tank A with a bare-wire low-voltage electric heater introduced therein. The difference between the two slopes obtained with and with out the heater power is again in agreement with the heater power itself within experimental error. The present method requires only one ordinary glass-rod thermometer as the essential measuring tool and no modification in the ultrasonic equipment, nevertheless its reliability is excellent and it promises to be a very practical means to determine the total acoustic power within the fluid.
  • 池谷 和夫, 久野 和宏, 鹿野 洋治
    原稿種別: 本文
    1969 年 25 巻 4 号 p. 199-208
    発行日: 1969/07/20
    公開日: 2017/06/02
    ジャーナル フリー
    The effect of a plane discontinuity on a plane wave propagating in a tube of arbitrary cross section has been discussed on the basis of various points of view. In a previous paper the authors regarded the effect as an acoustic element analogous to a transformer in electrical circuits, and devoted their attention to the element with discontinuous reduction in cross section. In this paper, therefore, another important type of an acoustic transformer with circular cross section, as shown in Fig. 1, is studied by making use of the same theoretical treatment as before and the results are compared with the previous ones in order to clarify their points of difference as well as those of similarity. The sound field in a tube is rigorously evaluated by a quantitative analysis, and several examples of pressure amplitude distribution along the axis are plotted in Fig. 3. By examining this figure, we may be able to appreciate the effects of higher order modes in the vicinity of the discontinuity. Fig. 4 shows the manner in which the incident power subject to (0, 0) mode is divided into transmitted and reflected powers. Examples of transmission and reflection coefficients of (0, 0) mode are shown in Fig. 5, and input impedances of the acoustic transformer under consideration are shown in Fig. 6. Investigations based on a simple plane-wave approximation and a plane-piston approximation are also made and the results are compared with exact solution in order to obtain the limitation of each of the approximate methods. Moreover, the propagation of sound in a circular cylindrical tube with infinite rigid baffle is quantitatively analyzed as a special case of the acoustic trans-former and the results are shown in Figs. 8-10. The above investigation of the acoustic transformer leads us to a better understanding of its characteristics. Both simple plane-wave approximation and plane-piston approximation have superior merits, but it is undesirable to use these approximate methods beyond the limitations which depend on the frequency parameter ka and diameter ratio ξ of the tube. We should, further, give attention to the fact that the sound field is more sensitive to the method of approximation than the global quantities such as input impedance and transmission coefficient which are less dependent on the method of approximation.
  • 中山 剛
    原稿種別: 本文
    1969 年 25 巻 4 号 p. 209-213
    発行日: 1969/07/20
    公開日: 2017/06/02
    ジャーナル フリー
  • 小橋 豊
    原稿種別: 本文
    1969 年 25 巻 4 号 p. 214-217
    発行日: 1969/07/20
    公開日: 2017/06/02
    ジャーナル フリー
  • 小橋 豊
    原稿種別: 本文
    1969 年 25 巻 4 号 p. 224-
    発行日: 1969/07/20
    公開日: 2017/06/02
    ジャーナル フリー
  • 久我 新一
    原稿種別: 本文
    1969 年 25 巻 4 号 p. 226-
    発行日: 1969/07/20
    公開日: 2017/06/02
    ジャーナル フリー
  • 原稿種別: 付録等
    1969 年 25 巻 4 号 p. 240-242
    発行日: 1969/07/20
    公開日: 2017/06/02
    ジャーナル フリー
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