2次元丘陵地形を過ぎる安定成層流の数値解析

第1章 序論 第2章 丘陵地形の上流と下流地面上に滑り条件を課した場合-低Reynolds数から比較的高いReynolds数(数千)までを対象としたDNS- 第3章 丘陵地形の上流と下流地面上に滑り条件を課した場合-高Reynolds数を対象としたLES- 第4章 丘陵地形の表面とその下流地面上に滑り無し条件を課した場合-地形背後の剥離･再付着流れに対する安定成層の効果- 第5章 地面上全てに滑り無し条件を課した場合-地面境界層に埋没した丘陵地形の周辺流れ- 第6章 結論Made available in DSpace on 2012-07-04T00:33:59Z (GMT). No. of bitstreams: 2 uchida1.pdf: 10354397 bytes, checksum: 133262a8ae4180961fd42d9c025b7b40 (MD5) uchida2.pdf: 5689105 bytes, checksum: 90cfe46cf5fa74e50afc5caa05bc7b20 (MD5) Previous issue date: 1999-03-2

Shrouded wind turbine performance in yawed turbulent flow conditions

Artículo científico. Wind Engineering XX(X):1–7 ©The Author(s) 2021 Reprints and permission: sagepub.co.uk/journalsPermissions.nav DOI: 10.1177/ToBeAssigned www.sagepub.com/Wind turbines represent a growing energy source worldwide. In many cases, operating in turbulent and changing wind direction spots. In this work, we use a wind tunnel to analyse the effect of the turbulence in a wind turbine provided with a Wind Lens flow concentrator, under yaw conditions, for turbulence intensity values of 10% and 15%. Measurements are made of the power coefficient as a function of the Tip Speed Ratio using two types of Wind Lens, CiiB5 and CiiB10, at yaw angles from 0 to 30 . In general, for the turbine with Wind Lens, an increase of the yaw angle causes a reduction of the power coefficient. If the turbine operates with the CiiB10, the stronger the turbulence, the greater performance is obtained. In conclusion, for the case of turbulent flow and yaw = 20 or less, the Wind Lens turbine offers better performance than without the flow concentrator

Consideration of the Behaviour of a Wind Turbine Wake Using High-Fidelity CFD Simulations

During operation of a wind turbine, wake flow occurs behind the wind turbine, reducing the amount of power generation and the life of the downwind wind turbine. To understand wind turbine wake flow, Computational Fluid Dynamics (CFD) simulations were conducted using 'RIAM-COMPACT' to reproduce wind turbine wake flow. There is no significant difference in the flow field of the wind turbine wake between upwind-type and downwind-type turbines. In the 5D downstream of the wind turbine, the vertical distribution of the mainstream velocity component is almost the same regardless of the power of the inflow profile in the swept area. When the inflow wind has a wind direction change of up to 10 degrees, the wind turbine wake is quite diffuse, and its vertical distribution is in good agreement with the field measurements made by the vertical profile lidar

New Evaluation Technique for WTG Design Wind Speed Using a CFD-Model-Based Unsteady Flow Simulation with Wind Direction Changes

Because a significant portion of the topography in Japan is characterized by steep, complex terrain, which results in a complex spatial distribution of wind speed, great care is necessary for selecting a site for the construction of wind turbine generators (WTG). We have developed a CFD model for unsteady flow called RIAM-COMPACT (Research Institute for Applied Mechanics, Kyushu University, computational prediction of airflow over complex terrain). The RIAM-COMPACT CFD model is based on large eddy simulation (LES). The computational domain of RIAM-COMPACT can extend from several meters to several kilometers, and RIAM-COMPACT can predict airflow and gas diffusion over complex terrain with high accuracy. The present paper proposes a technique for evaluating the deployment location of a WTG. The proposed technique employs the RIAM-COMPACT CFD model and simulates a continuous wind direction change over 360 degrees

Control of Surge in Centrifugal Compressor by Using a Nozzle Injection System: Universality in Optimal Position of Injection Nozzle

The passive control method for surge and rotating stall in centrifugal compressors by using a nozzle injection system was proposed to extend the stable operating range to the low flow rate. A part of the flow at the scroll outlet of a compressor was recirculated to an injection nozzle installed on the inner wall of the suction pipe of the compressor through the bypass pipe and injected to the impeller inlet. Two types of compressors were tested at the rotational speeds of 50,000 rpm and 60,000 rpm with the parameter of the circumferential position of the injection nozzle. The present experimental results revealed that the optimum circumferential position, which most effectively reduced the flow rate for the surge inception, existed at the opposite side of the tongue of the scroll against the rotational axis and did not depend on the compressor system and the rotational speeds

Comparative analysis on the physique and batting records of the players in the National Summer High School Baseball Tournaments before and after the adoption of metal bats.

To clarify the influence of the introduction of metal bats on the physique and batting records of the players in the National Summer High School Baseball Tournaments, a comparative analysis was conducted between height, body weight, body-weight ratio (body weight/height), batting average and home run average of the best four teams' players (n = 493) and those of the other teams' players (n = 4,590) in three periods: the period of the use of wooden bats, that of the use of both wooden and metal bats and that of the use of metal bats. In the period of metal bat use, the mean values of physique of the best four teams' players were significantly larger (P &#60; 0.05) and their average number of home runs was significantly higher than those of the other teams' players (P &#60; 0.01). The only significant differences between the two groups in those indices for each time period were for height in the wood and metal/wood periods. This study demonstrated that the differences between the home run average and physique, including height, body weight and body-weight ratio of the best four teams and the rest of the teams were the greatest after the use of metal bats. These findings suggest that the importance of the home run average increased and was associated with large-size of physique after the use of metal bats in the National Summer High School Baseball Tournaments.</p

Relation between the instrumental activities of daily living and physical fitness tests in elderly women.

A cross-sectional study was conducted to quantitatively evaluate the relationship between the instrumental activities of daily living (IADL) and various physical fitness tests in elderly women living at home. The study focused on the total population of those women aged 65 years and over living in Y Town, Hyogo Prefecture, Japan, who visited a nursing home for day services. A total of 128 subjects were divided into two groups: dependent in IADL group (n = 49) and independent in IADL group (n = 79). The magnitude of the relation was evaluated by the odds ratio (OR). The following tests showed a significant decrease in IADL: knee-raising test [age-adjusted OR = 4.23, 95% confidence interval (CI) 1.81-9.87], height (age-adjusted OR = 4.09, 95% CI 1.75-9.56), grip strength (age-adjusted OR = 3.68, 95% CI 1.57-8.60), sit-and-reach test (age-adjusted OR = 2.76, 95% CI 1.20-6.34), and standing on one leg with closed eyes (age-adjusted OR = 2.56, 95% CI 1.09-5.97). Multivariate analysis using Hayashi's quantification method I indicated that knee-raising was the test most highly correlated with decreased IADL. These results suggest that measurement of knee-raising ability, muscle strength of the lower extremities and flexibility of hip joint could be the most useful factors to assess the level of instrumental self-support ability.</p