著者

長谷川 豊 菊山 功嗣 谷本 正信 Gerard J. W. van Bussel

出版者

一般社団法人日本機械学会

雑誌

日本機械学會論文集. B編 (ISSN:03875016)

巻号頁・発行日

vol.63, no.608, pp.1297-1304, 1997-04-25

被引用文献数

6

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We describe a method of calculating yawed inflow effects on horizontal axis wind turbine rotors. Yawed inflow brings about asymmetric induced velocity distributions on the rotor plane due to an inclined vortex wake construction. For the calculation of yawed inflow phenomena, an inviscid aerodynamic model based on pressure distributions is adopted. Under the assumptions of an incompressible inviscid irrotational flow, the pressure perturbation satisfies the Laplace equation and acts as an acceleration potential function. The rotor blades are represented by spanwise and chordwise pressure distributions composed of analytical first-order asymptotic solutions to the Laplace equation. Integration of the accelerations determines the velocities in the rotor plane. With these velocities the aerodynamic loads can be calculated. An advantage of this model is that evaluation of the relatively complicated unstationary effects from the vorticity in the wake is not necessary in the calculation procedure.

著者

太田 有 大田 英輔 田島 清〓

出版者

一般社団法人日本機械学会

雑誌

日本機械学會論文集. B編 (ISSN:03875016)

巻号頁・発行日

vol.54, no.500, pp.890-899, 1988-04-25

被引用文献数

5

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Fan noise data are categorized into source characteristic terms and a frequency response term expressing attenuation in the propagation passage. These terms are determined by sweeping the fan speed from 1000 to 4500 rpm. The fan specific speed and the impeller diameter are 42 and 460 mm. The blade number is 12. By setting the exponent in a power law relationship of sound pressure level versus frequency as 3, two factors describing the source level are determined with simple relationships to the scroll cut-off location. By selecting the distance, the noise level is possibly reduced by more than 10 dB without influencing fan performance. The frequency response if satisfactorily presented by introducing a one-dimensional linear wave model, where the key passage is blade passages selectively determined by the noise wavelength. By choosing the blade number or the inlet duct length so that a frequency of the maximum attenuation is achieved, a noise reduction of 10 dB is again expected.

著者

井上 雅弘 金子 賢二 瀬戸口 俊明 猿渡 哲郎

出版者

一般社団法人日本機械学会

雑誌

日本機械学會論文集. B編 (ISSN:03875016)

巻号頁・発行日

vol.53, no.496, pp.3691-3698, 1987-12-25

被引用文献数

6

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A Wells turbine operating under irregular wave conditions has been analyzed theoretically. It is shown that the turbine performance depends on a unique parameter, including characteristic parameters of the irregular wave, turbine speed and dimensions of the turbine and air chamber. In order to obtain the optimum value of this parameter, a model test has been performed using a computer-controlled wind tunnel, which can simulate arbitrary oscillating flows based on spectra of irregular waves. From this value a set of optimum dimensions of a Wells turbine system can be determined. Furthermore, starting and running characteristics of the Wells turbine have been obtained by a computer simulation. It is possible to predict the optimum value of the parameter and behavior of the output coefficient by computer simulation.

著者

鈴木 健二郎 林 哲郎 SCHUERGER Matthew J. 西原 淳夫 林 政克

出版者

一般社団法人日本機械学会

雑誌

日本機械学會論文集. B編 (ISSN:03875016)

巻号頁・発行日

vol.55, no.516, pp.2457-2464, 1989-08-25

被引用文献数

2

---

The interruption of a fin surface causes renewed boundary layers starting from the leading edge of each interrupted fin. This results in boundary layer thinner in the average over entire length of fin surfaces compared to the uninterrupted case. Therefore, a higher degree of interruption is normally expected to lead to a higher degree of heat transfer. However, to realize this expectation actually, care must be taken of the geometrical allocation of each fin in an array so as to avoid other undesirable effects relating to the fin geometry. Numerical computation of flow and thermal fields have been made for two-dimensional models of two types of parallel louver fins and an offset fin. Heat transfer characteristics of parallel louver fins are discussed in comparison with those of an offset fin based upon the results obtained from the performed numerical computation. It is demonstrated that a cartain type of parallel louver fin has a higher heat transfer performance than that obtained with an offset fin.

著者

山内 庄司 中西 重康 石谷 清幹

出版者

一般社団法人日本機械学会

雑誌

日本機械学會論文集. B編 (ISSN:03875016)

巻号頁・発行日

vol.47, no.416, pp.693-702, 1981-04-25

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蒸発管内密度波振動(流れ逸走を含む)の安定限界に対し, 各種因子が及ぼす効果について, 広範囲に解析的に検討した. 圧力降下一定の均一加熱管を対象に, 均質流モデルを用いて解析し, 7個の無次元パラメータによるスケーリングが可能であることを示した. また, 基礎式を線形化, ラプラス変換して得た特性方程式を用いて, ラプラス平面の虚軸をパラメータ空間に写像(ネイマルクのD分割法)することにより, いくつかのパラメータ平面で安定限界の形状を示した. 特に線形パラメータ面上では, D分割境界線の形状に双曲線状のものとだ円状のものがあり, 前者では, 安定限界は対応する漸近線にほぼ一致することを示した. また蒸発管内流動時間と安定限界振動数との関係についても検討し, 奇数次の振動が可能なこと, 本モデルでは極端な例を除いて基本振動が最不安定であることなどを示した

著者

和栗 雄太郎

出版者

一般社団法人日本機械学会

雑誌

日本機械学會論文集. B編 (ISSN:03875016)

巻号頁・発行日

vol.65, no.634, pp.1859-1861, 1999-06-25

著者

佐藤 正隆

出版者

一般社団法人日本機械学会

雑誌

日本機械学會論文集. B編 (ISSN:03875016)

巻号頁・発行日

vol.51, no.464, pp.1235-1242, 1985-04-25

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著者は以前従来のネゲントロビの定義を変更してエントロビ差による定義を提案したが,これは孤立系に基づくもので,一般の状況下にある系に適用するには更に定義の変更が必要になる.本報ではKullback-Leiblerの情報量による定義を提案し,これによるネゲントロビが正値性や非平衡性,仕事の可能性を表すことを示し,さらにエクセルギを導くことを見た.拡張されたネゲントロビは,その一部として拡張前の懸念を含んでいる.

著者

佐藤 正隆

出版者

一般社団法人日本機械学会

雑誌

日本機械学會論文集. B編 (ISSN:03875016)

巻号頁・発行日

vol.53, no.493, pp.2863-2868, 1987-09-25

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The capacity of negentropy is the maximum negentropy that a system can have. For example, the negentropy contained by a cylinder-piston system becomes larger as the piston is moved inward, but practically it has a maximum, namely, the capacity of negentropy. Generally, capacity represents a certain type of macroscopic order (capacity-type of order) which comes from the relation between molecules, and without this type of order, negentropy cannot beheld by a system. Capacity-type of order is regarded as a pattern which has the property of recovering its origin in thermodynamic situations, and the order may be destroyed by negentropy which exceeds the capacity. Although nonequilibrium-type of order, which is represented by negentropy, differs from the capacity-type of order, they are intimately related with each other. The general definition of the capacity is made in a statistical-mechanical manner based on negentropy defined by Kullback-Leibler information.

著者

許斐 敏明 石山 忍

出版者

一般社団法人日本機械学会

雑誌

日本機械学會論文集. B編 (ISSN:03875016)

巻号頁・発行日

vol.48, no.434, pp.2127-2133, 1982-10-25

被引用文献数

1

---

エンジンのシリンダ内圧力, 正味トルク, クランク角速度からサイクル内摩擦トルク変化を計測することを試みた. これに必要な高精度角速度計, および多気筒のシリンダ内圧力と回転数を同時に時系列に記録できる解析装置, 両者を開発した. これらを用いた実験から, この方法は従来の平均値のみの計測よりも多くの知見が得られることおよび駆動系のねじり振動解析におけるエンジン減衰係数の測定にも利用できることがわかった.

著者

須賀 一彦

出版者

一般社団法人日本機械学会

雑誌

日本機械学會論文集. B編 (ISSN:03875016)

巻号頁・発行日

vol.70, no.697, pp.2386-2393, 2004-09-25

被引用文献数

1

---

Modeling the pressure-diffusion process is discussed to improve the prediction of turbulent recirculating flows by a second moment closure. Since the recent DNS research of a turbulent recirculating flow suggeted that the pressure-diffusion process of the turbulence energy was significant in the recirculating region, the present study focuses on the rapid part of the process consisting of the mean shear. This rapid pressure-diffusion model is developed for the Reynolds stress equation using the two-component limit turbulence condition and added to a low Reynolds number two-component-limit full second moment closure for evaluation. Its effects are discussed through applications of turbulent recirculating flows such as a trailing-edge and a back-step flows. Encouraging results are obtained though some margins to be improved still remain.

著者

庄司 正弘 涌永 隆夫 児玉 健

出版者

一般社団法人日本機械学会

雑誌

日本機械学會論文集. B編 (ISSN:03875016)

巻号頁・発行日

vol.50, no.451, pp.716-723, 1984-03-28

被引用文献数

3

---

噴霧冷却の基礎研究として、均質、単一の液滴列(サブクール液滴)を用い、特に高加熱面温度領域(非ぬれ領域)の伝熱特性につき実験的に研究した。その結果、熱伝達は加熱面温度によらず一定となること、液サブクールに比列して増加すること、液滴1個当たり伝熱量qは液滴の体積に比例し、液滴速度にほとんどよらないこと、qに関するデータは実用的な次式でよくまとまることを示した。q=π/(12)d^3ρcΔT_<SUB>

著者

親川 兼勇 屋我 実 那須 謙一 瀬名波 出 松田 昇一 安座間 工

出版者

一般社団法人日本機械学会

雑誌

日本機械学會論文集. B編 (ISSN:03875016)

巻号頁・発行日

vol.63, no.607, pp.979-985, 1997-03-25

被引用文献数

4

---

Heat transfer characteristics and flow patterns were measured over the plate for various separation distances between the nozzle exit and target plate when the air issuing from a sharpedged cross-shaped nozzle impinges on the plate. The local heat transfer coefficients in the radial direction for different circumferential positions were calculated using the wall temperatures measured by means of thermocouples, and the flow patterns were observed using a oil-titanium IV oxide method. The isotherms of the infrared images were also measured using an infrared radiometer with a two-dimensional array of InSb sensors. The geometric axes were switched due to the self-induced velocity of a vortex filament ; the convex corners became flat and the concave corners generated outward ejection. The distribution of the iso-heat-transfer-coefficient contours corresponds well to the flow pattern and the isotherm contours. These contours extended diagonally and demonstrated the Andrew's cross pattern for the short separations, subsequently becoming the octagonal patten, and then becoming circular at large separations. The correspondence of the heat transfer characteristic to the flow behaviors, and the heat transfer mechanism were also described.

著者

河田 剛毅 前川 博 小林 睦夫 斉藤 北

出版者

一般社団法人日本機械学会

雑誌

日本機械学會論文集. B編 (ISSN:03875016)

巻号頁・発行日

vol.57, no.540, pp.2812-2817, 1991-08-25

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Spanwise eddy diffusivity of heat was measured in a flat-plate turbulent boundary layer with a constant spanwise temperature gradient and different intensities of free-stream turbulence. Comparison was made with the usual kinematic eddy viscosity measured in parallel. According to the experimental results, the ratio of these eddy diffusivities is strongly influenced by the free-stream turbulence. However, in the vicinity of the wall, this ratio approaches a certain universal distribution which is independent of the intensity of free-stream turbulence.

著者

岡島 厚 大津山 澄明 永森 稔朗 中野 智仁 木綿 隆弘

出版者

一般社団法人日本機械学会

雑誌

日本機械学會論文集. B編 (ISSN:03875016)

巻号頁・発行日

vol.65, no.635, pp.2196-2203, 1999-07-25

被引用文献数

19

---

Flow induced in-line oscillation of a structure with a circular or rectangular section was experimentally studied by free-oscillation tests in a wind tunnel. Detailed data of response amplitude of various cylinders have been acquired in a wide range of the reduced mass-damping parameter (Scruton number), by free-oscillation tests of two-dimensional cylinder spring-mounted to oscillate as a rigid cylinder. Flow induced in-line oscillation of the cylinder is certified to have two types of excitation mechanism; one is the so-called wake breathing effect accompanied with a symmetric vortex street and the other is the vortex excitation at a half of the critical reduced velocity. Also a fixed splitter plate was mounted behind a cylinder to eliminate the vortex shedding of alternate vortices from the cylinder, after Aguirre's experiments, and the results were compared with those without a splitter plate. As a result, we can classify the flow induced in line oscillation of the circular or rectangular cylinder. For a circular cylinder and a square one, two types of excitation phenomena appear in each reduced velocity region, the thin rectangular cylinder with the side ratio b/h=0.4 suffers from the vortex excitation, and the elongated rectangular cylinder with the side ratio b/h=2.5, is subjected to the wake breathing effect accompanied with a symmetric vortex street. It is found that fluidelastic characteristics of two types of in-line oscillations are quite different; i.e., the response amplitude are very sensitive to the reduced massdamping parameter, during the in line oscillation with a symmetric vortex street, while the oscillation of vortex excitation are rather insensitive.

著者

大塚 芳郎 北野 三千雄

出版者

一般社団法人日本機械学会

雑誌

日本機械学會論文集. B編 (ISSN:03875016)

巻号頁・発行日

vol.48, no.433, pp.1818-1825, 1982-09-25

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円管内層流拡散炎のすす限界を, 燃焼管直径, 燃料管直径, 空気流速および燃料流速を広範囲に変化させて, メタン, エタン, プロパン, 正ブタン, アセチレンおよびエチレンの6種の炭化水素について測定した. すす限界は, 空気比λ, 燃料流量V_fおよび燃焼管直径によって支配され, すす限界直線の傾斜d log<λ/d log V_fの大小によって, すす限界はアセチレン形とメタン系に分けられ, 前者はすすの大粒子の, 後者は小粒子の微量化する限界である.

著者

安倍 賢一 長野 靖尚 近藤 継男

出版者

一般社団法人日本機械学会

雑誌

日本機械学會論文集. B編 (ISSN:03875016)

巻号頁・発行日

vol.60, no.573, pp.1743-1750, 1994-05-25

被引用文献数

3

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We propose a new two-equation heat-transfer model which is modified from the model developed by Nagano, Tagawa and Tsuji (Proc. ASME/JSME Thermal Eng. Joint Conf., 3 (1991), 233). The main improvement is made by introducing the Kolmogorov velocity scale, u_ε≡(νε)^<1/4>, instead of the friction velocity u_τ, to account for the wall-limiting behavior. After investigating the characteristics of various time scales for the heat-transfer model, we employed a composite time scale which gives weight to a shorter scale among the velocity- and temperature-field time scales. With these modifications, it is shown that the present model quite successfully predicts the turbulent heat transfer in a boundary layer subjected to sudden change of heat flux, and in a separating and reattaching flow downstream of a backward-facing step.

著者

西村 智行 持丸 義弘

出版者

一般社団法人日本機械学会

雑誌

日本機械学會論文集. B編 (ISSN:03875016)

巻号頁・発行日

vol.63, no.611, pp.2309-2315, 1997-07-25

被引用文献数

1 1

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A spectral finite difference method with domain decomposition is used to solve the Navier-Stokes equation for incompressible fluids. In the domain decomposition method, some subgrids consisting of multiple orthogonal curvilinear coordinate systems and of overlapping region (s) are adopted, and one-dimensional interpolation is applied to the overlapping region in the case of two-dimensional analysis to obtain neighboring values corresponding to a virtual boundary. Mass conservation on a virtual boundary is assured using a mass imbalance correction. Present numerical analyses for two-dimensional, internal, doubly-connected or triply-connected flow fields consisting of cylindric and elliptic boundaries show good consistency, accuracy and efficiency.

著者

佐藤 学 伊藤 勝宏 小野寺 収 高山 和喜 辻田 誠

出版者

一般社団法人日本機械学会

雑誌

日本機械学會論文集. B編 (ISSN:03875016)

巻号頁・発行日

vol.55, no.509, pp.95-100, 1989-01-25

被引用文献数

1

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A new concept of a super charger for diesel engines is proposed and its performance is examined by TVD numerical simulation. The structure of the super charger has a simple duct-valve system which allows the feeding of compressed inlet air to the engine cylinder by an exhaust-gas driven chock wave. The two-dimensional unsteady flow of this duct-valve system was simulated by TVD numerical scheme applied to the Euler equations. It was found that the present supercharger has a performance which is preferable to low engine speed. The complicated wave interactions are simulated in detail.

著者

横堀 誠一 笠木 伸英 平田 賢

出版者

一般社団法人日本機械学会

雑誌

日本機械学會論文集. B編 (ISSN:03875016)

巻号頁・発行日

vol.49, no.441, pp.1029-1039, 1983-05-25

被引用文献数

3

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本論文は二次元衝突噴流のよどみ領域における流動構造および伝熱機構を実験的に明らかにしたものである.流れの可視化によってよどみ域は大きなスケールの乱流渦構造がスパン方向に非定常に発生することを明らかにしこれらの構造が自由噴流せん断部の渦糸の伸張から生じていることを示した.ついでにこの構造がよどみ点での伝熱促進に果たす役割について顕著な効果のあることを非定常温度場の可視化によって示した.

著者

清水 幸丸 村上 光清 葛原 定郎 永房 誠 杉野 公一

出版者

一般社団法人日本機械学会

雑誌

日本機械学會論文集. B編 (ISSN:03875016)

巻号頁・発行日

vol.47, no.417, pp.729-738, 1981-05-25

被引用文献数

1

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本研究は, ディフューザの中心線がねじれS字状およびコイル状に曲げられた, いわゆる空間曲りデュフューザについて, その性能を調べたものである. このようなディフューザでは, 流入速度が通常の曲り管出口における速度分布のように二次流れを伴って不均一になっている場合には, この不均一流がディフューザの曲りと関連して, ディフューザ内に強い二次旋回成分を発生することとなり, はく離の発生が防止される. そして直線円すいディフューザよりも高い圧力回復効率を示すことを明らかにした.