Design and Performance of Cambered-Airfoil Turning Vanes in Duct Elbows

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基本資料

Project title

Code/計畫編號

MOST104-2221-E019-031

Translated Name/計畫中文名

以曲翼型導葉片改善彎角管道效能的設計

Project Coordinator/計畫主持人

Shun-Chang Yen

Funding Organization/主管機關

National Science and Technology Council

Department/Unit

Department of Mechanical and Mechatronic Engineering

Website

https://www.grb.gov.tw/search/planDetail?id=11572090

Year

2015

Start date/計畫起

01-08-2015

Expected Completion/計畫迄

01-07-2016

Bugetid/研究經費

667千元

ResearchField/研究領域

機械工程

"本計畫書擬議一個實驗研究方式，進行以導葉片(Turning Vanes)的被動控制裝置，來改善彎角管道(Duct Elbows) 流量效能的提升。以彎曲薄板(Curved-thin plate) 及曲翼型 (Cambered-airfoil)的導葉片在不同間距比(Gap ratio)的條件下，對不同彎角度管道的流量效能提升之研究。申請人基於近二年來協助合作企業—和光工業公司，開發新穎靜音型烘手機的流道設計，過程中發現烘手機內部空間狹小，致使烘手空氣流路的管道方向變化相當大；尤其是空氣流過彎道時，是否流暢，會大大影響烘手機的出風口風量及機器本體的振動與噪音。這是因為彎角管道會因離心力作用，發生內壁與外壁的壓差與流速不同，產生二次分離流(Second separation)與壓力降損失(Pressure loss)，進而影響流場速度分佈的均勻性。因此本計畫將嘗試，如能以「技術發展」層面的觀點，結合申請人先前研究的結果，以不同型式的導葉片在間距比的條件下，對彎角度變化的管道，進行效能提升之研究。其結果可適用於多種通風管道的設計與開發，並在傳統工業界的開發上有極高的價值與應用性。有鑑於此，在此專題研究計畫中以彎曲薄板及曲翼型的二類多種形式導葉片，構置於開放下吹式風洞的測試區具有彎角管道中，進行不同導葉片形狀、間距比、旋長、數目、速度等的研究。藉由調制導葉片參數，進而抵銷彎角管道所產生二次分離流的回流泡大小，並同時回饋量測彎角管道的上、下流域的流場分佈、壓力分佈、噪音分佈等影響一併加入探討。過程中將以煙線流場可視化技術、PIV 量測系統、拓樸理論的分析應用、熱線風速儀、壓力掃描器(Linear pressure scanner)、與噪音分貝計等交互應用，以尋找出最佳化的設計規則與操作條件，並探討受導葉片所調控的彎角管道的幾何配置選取、流場行為、壓力降頭損、紊流動能特性、以及非穩態流動與尾流的調制能力。煙線流場可視化技術、PIV 系統觀察量測導葉片間的流場特徵模態，並輔與運用臨界點理論之拓樸學的分析應用，用來確定複雜的流場結構模態。熱線風速儀可以偵測導葉片的流場行為，包含由壓力及速度梯度所產生的渦街(Vortex street)及剪流層不穩定波(Shear layer instability)之間機制的差異。利用壓力掃描器擷取彎角管道受導葉片所產生壓力分佈，並經由理論的計算得到壓力損失的大小。使用噪音分貝計偵測彎角管道的音頻譜與分貝，有效確認葉片通過頻率(Blade passing frequency, bpf)及其倍頻。將流體流過彎角管道受不同導葉片形狀、間距比、數目所調制時，彎角管道中的流場行為、壓力降頭損、流量、速度特性與噪音的關聯性做討論。" "This project experimentally utilizes the turning vanes to study the performance of duct elbows. The profiles of turning vanes are curved-thin plate and cambered airfoil. The influence of gap ratio of the turning vanes is also included. In the last two years, the applicant cooperated with HOKWANG Industrial Company (和光工業公司) to develop a innovative high-efficient and low-noised hand dryer. The research results reveal that the flow channel changed abruptly in the cramped space. Specifically, the fluency of airflow passing through the flow channel will influence apparently the exit flow rate, the vibration and noise of dryer body. The centrifugal effect occurring at the duct elbow causes the flow-speed difference between the inner and outer walls. Furthermore, the second separation and pressure loss result in the non-uniformity of velocity distribution. In this project, the applicant will join the previous results and utilize different gap ratios to explore the performance of duct elbows. The research results will be applied in the design and manufacture of flow channel. In this project, two kinds of turning vanes, curved-thin plate and cambered airfoil, will be installed in the duct elbow to test the performance of a wind tunnel. The experiment parameters include the shape of turning vane, the gap ratio between turning vanes, the number of turning vanes and the free-stream velocity. These experimental factors will be considered comprehensively to shrink the second-separation bubble. The contraction of second-separation bubble will feedback the control factors on the upstream/down-stream flow distribution, pressure distribution and noise decibel. The experimental tools include the smoke-streak flow visualization, particle-image velocimetry (PIV), topological analysis, hot-wire velocimetry, linear pressure scanner and decibel meter. The flow performance considers the geometrical arrangement of turning vane in the duct elbows, flow behaviors, pressure head loss, turbulence characteristics, unstable flow and wake modulation. The smoke-streak flow visualization and PIV explore the flow characteristic patterns around the turning vanes. The topological flow analysis utilizes the critical point theorem to determine the flow structures. The hot-wire velocimetry examines the velocity distribution and vortex street caused from the velocity gradient and the difference between the shear-layer instability. The pressure scanner will be utilized to measure the pressure distribution resulted from the existence of turning vane. Furthermore, the pressure head loss will be determined. The decibel meter detect the noise spectrum and noise level; and confirm the blade passing frequency (bpf) and multiple-frequency phenomenon of turning vanes. Consequently, the flow behaviors, pressure head loss, flow rate, velocity property and noise level in the duct elbows will be comprehensively discussed with considering the shape of turning vane, the gap ratio of turning vanes and the amount of turning vanes."

Keyword(s)

導葉片
彎角管道
彎曲薄板
曲翼型
Turning vanes
Duct elbows
Curved-thin plate
Cambered airfoil

DSpace CRIS

Design and Performance of Cambered-Airfoil Turning Vanes in Duct Elbows

基本資料

Description