1305810 九、發明說明 【發明所屬之技術領域】 且特別是有關於一種邊 本發明是有關於一種散熱風扇 界層控制技術之散熱風扇。 【先前技術】 子產品持續朝高速化、薄型化以及小型化的趨勢BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cooling fan for a cooling fan boundary layer control technique. [Prior Art] Sub-products continue to move toward higher speed, thinner, and smaller
發展，使彳于裝置散熱問題日κ胃 、 1畸日皿嚴峻。傳統利甩機構開孔所造 成的自㈣流效應已無法符合目前電子產品的散熱需求。一 般研究認為自然對流的界線約在熱密度聰i左右，因此搭 配冷卻風扇作為线熱對策的方式目前已非常普遍。由於風 扇成本低廉，隸由風扇對流體做功所產生的效應，可極為 有效率地提升裝置之散熱效能。 a »月參照第1圖’其係緣示傳統散熱風扇之風扇轉子的示 意圖…般而言，散熱風扇主要係由風扇轉子⑽所組成， 並利用驅動馬達來驅動風扇轉子⑽風扇轉子⑽至少包括 輪轂102以及數片扇葉104,其中這些扇葉1〇4與輪轂102接 當氣流流經風扇之扇葉104表面106時，由於扇葉104 之表面/G6的黏滞力阻礙氣流進行，流場邊界層效應立即產 生，如第2圓之A點流場所示，因而影響氣流質點往後移動 的趨勢’此壓力稱之為逆壓力，此逆壓力的產生即為空氣阻 力的增加。不久，扇葉1G4之表面1G6上的邊界層出現分離 點（Separation Point)，如第2圖之B點流場所示，隨後則產生 5 1305810 紊流如第2圖之C點流場所示。當扇葉1 〇4之表面1 〇6上的 邊界層出現分離點後，由於壓力梯度的變化使得風扇整體效 率下降，同時也會增加驅動馬達的負擔，換言之，風扇要維 持相同的轉速便須提升馬達功率的輸入，因此導致風扇之耗 電量增加，相當不利於風扇的應用。 【發明内容】 因此，本發明之目的就是在提供一種散熱風扇，係在風 鲁扇扇葉之吸力面設置粗糙區，以延遲風扇之扇葉表面之氣流 刀離的產生，故可改善風扇邊界層剝離的現象，進一步有效 改善風扇性能’達到提高風扇效率的功效。 本發明之另一目的是在提供一種散熱風扇，可減少驅動 馬達之需求功率’具有省電環保的優勢。 本發明之又一目的是在提供一種散熱風扇，可以一體成 型的射出成型技術直接製作具有粗糙區之風扇扇葉，容易製 作：而具有成本優勢。另外’亦可於風扇之扇葉成型後，利 籲用後加工方式在扇葉上設置或修改粗糙區，因此可立即改善 風扇之效能。 根據本發明之上述目#，提出一種散熱風扇，至少包括 風扇轉子以及驅動馬達，其中驅動馬達用以驅動風扇轉子。 ^風扇料至少包括：—輪穀；以及複數個扇葉，與輪轂接 ° /、中每扇葉之吸力面設有至少一粗糙區，以改善這些 扇葉之邊界層剝離的現象。 依照本發明一較佳實施例，每一扇葉之粗糙區包括複數 1305810 個半圓形凸塊，且每—扇葉之粗縫區較佳係位於每—扇葉之 氣流分離點之前。 〃 >依照本發明另一較佳實施例’每一扇葉均為翼型結構， 且每-扇葉之粗糙區較佳係設於翼型結構之翼 ^Development, so that the device heat dissipation problem κ stomach, 1 terrible dish is severe. The self-(four) flow effect caused by the opening of the traditional Lishui mechanism has been unable to meet the current heat dissipation requirements of electronic products. In general, the boundary of natural convection is about the heat density, so it is very common to use a cooling fan as a line heat countermeasure. Due to the low cost of the fan, the effect of the fan on the work of the fluid can greatly improve the heat dissipation performance of the device. a » month refers to the schematic diagram of the fan rotor of the conventional cooling fan according to Fig. 1 . Generally speaking, the cooling fan is mainly composed of a fan rotor (10), and uses a driving motor to drive the fan rotor (10). The fan rotor (10) includes at least The hub 102 and the plurality of blades 104, wherein the blades 1〇4 and the hub 102 are connected to each other when the airflow flows through the surface 106 of the fan blade 104, and the flow is blocked due to the viscous force of the surface of the blade 104/G6. The field boundary layer effect is immediately generated, as shown by the flow field at point A of the second circle, thus affecting the tendency of the gas flow point to move backwards. This pressure is called the reverse pressure, and the generation of the reverse pressure is the increase of the air resistance. Soon, the separation point on the surface 1G6 of the fan blade 1G4 appears as a separation point, as shown in the flow field at point B in Fig. 2, and then generates 5 1305810 turbulence as shown in the flow point of point C in Fig. 2. . When the boundary layer on the surface 1 〇6 of the blade 1 〇4 has a separation point, the overall efficiency of the fan is lowered due to the change of the pressure gradient, and the load on the drive motor is also increased. In other words, the fan must maintain the same rotational speed. Increasing the input of the motor power, thus causing an increase in the power consumption of the fan, is quite unfavorable for the application of the fan. SUMMARY OF THE INVENTION Accordingly, it is an object of the present invention to provide a heat dissipating fan which is provided with a roughened area on the suction surface of the fan blade to delay the generation of the airflow of the fan blade surface, thereby improving the fan boundary. The phenomenon of layer peeling further improves the fan performance' to achieve the effect of improving fan efficiency. Another object of the present invention is to provide a heat dissipating fan which can reduce the power required by the driving motor to have the advantages of power saving and environmental protection. Still another object of the present invention is to provide a heat dissipating fan which can directly produce a fan blade having a roughened area by an integrally formed injection molding technique, which is easy to manufacture: and has a cost advantage. In addition, after the fan blades of the fan are formed, the rough processing can be set or modified on the blade by post-processing, so that the performance of the fan can be improved immediately. According to the above aspect of the invention, there is provided a heat dissipating fan comprising at least a fan rotor and a drive motor, wherein the drive motor is for driving the fan rotor. The fan material comprises at least: a trough; and a plurality of blades, and the suction surface of each of the blades is provided with at least one roughened area to improve the peeling of the boundary layer of the blades. In accordance with a preferred embodiment of the present invention, the roughened area of each blade includes a plurality of 1305810 semi-circular bumps, and each of the coarse-slotted areas of the blade is preferably located before the air separation point of each of the blades. 〃 > In accordance with another preferred embodiment of the present invention, each of the blades is an airfoil structure, and the rough region of each blade is preferably attached to the wing of the airfoil structure ^
Edge) 〇 5Edge) 〇 5
藉由在扇葉表面設置粗糙度，並利用氣流通過粗糙度表 面所產生的動能來延遲氣流分離的產生，進而達到提高風扇 性能與效率、以及降低驅動馬達的需求功率的目的。因此， 本發明之散熱風扇具有高效能、省電等優點。 【實施方式】 本發明揭露一種散熱風扇，係利用邊界層控制理論為基 礎於風扇吸力面上進行粗縫度設計，因此可以最具經濟優 、式來改。風扇邊界層剥離的現象，藉此達到改善風扇 性能二以及提升風屬使用效率之目的。為了使本發明之敘述 更加詳盡與兀借’可參照下列描述並配合第3圖至第！ i圖之 圖示。 在軸流散熱風扇中’除了其扇葉與機翼理論相似外，扇 、同樣存在氣離問題。因此，對於散執風扇而言，除 了扇葉之基本翼型鱼眉塋 · 兴土，、屬葉攻角設計的最佳化外，解決氣流剝 T的現象也疋提升風扇性能的方式之一。有鑑於此，本發明 ，出-種散熱風扇，係利用邊界層控制技術，來有效解決風 扇之扇葉的氣流剝離現象。 月 > ”、、第3圖，其繪示依照本發明一較佳實施例的一種 7 1305810 政熱風扇之風扇轉子的示意。—^ 由風扇轉子200所缸杰，廿 般而吕，散熱風扇主要係 200。 、 、利用驅動馬達來驅動風扇轉子 200。風扇轉子2〇〇 5 /丨少^；#4^孟 中、古此戶接 乂已括輪轂202以及數片扇葉204，其 中ϋ二扇葉204與輪轂202接合。机上 +门卢 先依一氣動力學理論設計㈣帛2Q4 輔助設計（CAD)軟體喻製出1古、试 〜用1：腦 J歡體，，會裏出具有扭轉角度的3D立體 2〇4’並將這些扇葉2〇4連接至輪轂2〇2結構上。 、 扇葉綱之吸力面2〇6上設有至少一粗趟區212，其中粗 糙& 212包括數個微結構2〇8。在本發明中，微結構2⑽可為 凸塊結構，如f 4A圖所示之扇葉2()4a之吸力自2Q6a上所設 之凸塊麻，或者可為凹陷結構，如第化圖所示之扇葉鳩 之吸力面2〇6b上所設之凹陷2_。如第5圖所示，微結構 2 〇 8可為許多不同形狀的結構，例如半圓形/弧形& '弧面在前 端之扇形b、弧面在後端之扇形c、三角形d〜f、或矩形§〜匕。 在本發明中，於扇葉204之氣流分離點之前需設有粗縫 區212。因此’設置粗糙區212時，可先利用計算流體力學（cfd 軟體來模擬風扇轉子200之流場狀況，並依據模擬結果對照 風扇轉子200測試結果之特性，分析風扇轉子2〇〇之扇葉2〇4 的表面是否產生氣流剝離之現象，並藉此取得扇葉2〇4表面 的氣流分離點D，如第6圖所示。接著，至少在扇葉2〇4之吸 力面206的氣流分離點D之前’設置粗糙區212。在本發明之 一較佳實施例中，粗糙區212係設在每個扇葉2〇4之翼前緣 210處’亦即微結構2 0 8係排列在扇葉2 〇 4之翼前緣21 〇上， 如第3圖所示。然而，如第7圖所示之風扇轉子3〇〇，本發明 1305810 亦可佈設在每個扇葉3〇4之吸力面 表面上，其中這些扇葉3〇4接合在輪較3〇2上。 體 請再次參照第3圖’在本發明中，每片… 皆為相同，且| Η芦1 〜狀 片羽葉204均具有翼型結構，亦即扇葉2〇4 ::面為翼型’如“圖所示。本發明之粗糙區212較佳可 佈设在扇葉204的翼型畲'、9 义 舌 _ 異生重心214之前，也就是在扇葉204的 董心之刖。 在本發明之一實施例中’粗糙區212所包 =圓形凸塊’且這些微結構係以單列排列二： 構㈣之間的間距=:二緣21°處。相鄰之二微結 較佳為實質介於每個微結構208之官 度218的°.5倍至1倍之間，如“圖所示。此外，每個：： 構2〇8之厚度222較佳係實質為扇葉2〇4之翼型結構的最: 厚度220 # 〇·5倍以内’更佳為實質介於扇葉204之翼型姓構 的最大厚度22°的0.1倍至〇_5倍之間，如第9圖所示； 以上所述僅係本發明之—實施例，本發明並不㈣此: =區：設在扇葉之氣流分離點之前以達改善邊界層剝離 象外，本發明之扇葉吸力面上之粗糖區設置位置及微結構之 尺寸與密度可依風扇及其所裝設之產品的需求，而加以調整。 在本發明中’風扇轉子200可為一體成型之結構 之扇葉204與輪轂202係一體之結構，其中風扇轉子_ 材質可為塑膠，且可制例如射出成型的方式來製作風扇轉 ^ 200。古製作風扇轉子2〇0時’可利用模具，其中此模具可預 先就設有粗糙區，因此透過此一模具即可獲得吸力面206上 1305810 具有粗糙區212之扇葉2〇4。然而，在本發明之其他實施例中， 製作風扇轉子200之模具可不預先設有粗糙區，可待風扇轉 子200之主體架構完成後，再利用加工方式於扇葉2〇4之吸 力面206上設置粗糙區212’此時粗糙區212係一後加工結構。 由於扇葉204之吸力面206上具有微結構2〇8佈設之粗 糙區2丨2,因此氣流經過粗糙區212時會產生紊流現象，如此 一來，藉由氣流經過粗糙面所產生的動能，可消除扇葉2〇4 之吸力面206的速度梯度，而可延遲或改善氣流分離點的產 生，進而可增加風扇整體之效率。 經由測試後發現，在相同風量下，本發明具有粗糙區之 扇葉的散熱風扇所需之輸入功率小於傳統風扇’如第1〇圖所 不。而且，本發明之散熱風扇的效率々較傳統風扇的效率佳’ 如第11圖所示。纟此可知，冑用本發明之散熱風扇，可有效 提升風扇之性能與效率，並可節省驅動馬達之耗電率。 由上述本發明較佳實施例可知，本發明之優點就是因為 本發明之散熱風扇在扇葉表面設置粗糙度，並利用氣流通過 粗糙度表面所產生的動能來延遲氣流分離的產生。因此，可 有效提高風扇性能與效率’並可降低驅動馬達的需求功率。 故本發明之散熱風扇具有高效能、以及省電環保等優勢。 由上述本發明較佳實施例可知，本發明之另一優點為可 利用一體成型的射出成型技術直接製作具有粗糙區之風扇扇 葉，因此相當容易製作，而具有成本優勢。另外，更可於風 扇之扇葉主體成型後，利用後加工方式在扇葉上設置或修改 粗糙區’因此可立即改善風扇之效能，應用性佳。 1305810 雖然本發明已以一較佳實施例揭露如上，然 ::本發明’任何在此技術領域中具有通常知識者 ： 離本發明之精神和範圍内，當可作各q 脫 本發明之保m j 4乍各種之更動與潤飾，因此 月之保護乾圍當視後附之申請專利範圍所界定者為準。 【圖式簡單說明】 :1圖係繪示傳統散熱風扇之風扇轉子的示意圖。 2圖係“風扇之扇葉表面氣流分離之過程示意圖。 弟3圖係繪示依照本發明一較祛 之風扇轉子的示意圖。 較佳實施例的-種散熱風扇 圖係繪示依照本發明一較佳實施例 之扇读的局部剖面示意圖。 ‘，、、風扇 第4B圖係緣示依昭木 X. 扇之扇葉的“另一較佳實施例的-種散熱風 说茱的局部剖面示意圖。 :5圖係繪示本發明之數種微結構形狀的示意圖。 之心^^明一較佳實施例的-種散熱風扇 第7圖係繪示依照本發明另一較佳fβ & 扇之風扇轉子的示意圖。 肖佳貫罐種散熱風 之丄8圖係繪示依照本發明-較佳實施例的-種散熱風戶 之扇葉的上視示意圖。 …、風扇 Γ\ __ 圖係繪示依照本發明一較祛 之扇葉的剖面示意圖。 較佳實施例的-種散熱風扇 弟10圖係纷示本發明之散熱風扇與傳統具光滑表面之風 11 I3〇58l〇 212 216 220 300 304 308 b :. d ： 馬達的需求功率比較圖。 1圖係續示本發明 比較圖。 之散熱風扇與傳統多 件符號說明】 :風扇轉子 :扇葉 102 :輪轂 106 :表面 :風扇轉子 :扇葉 :扇葉 202 :輪轂 204a :扇葉 206 :吸力面 :吸力面 206b :吸力面 :微結構 208a :凸塊 :凹陷 210 :翼前緣 粗輪區 2 14 :翼型重心 間距 218 :寬度 厚度 222 :厚度 風扇轉子 302 :輪轂 扇葉 306 :吸力面 相糙區 1形 a :半圓形/弧形 c :扇形 i角形 e :三角形 L角形 δ形 g :矩形 面之風 12By setting the roughness on the surface of the blade and utilizing the kinetic energy generated by the airflow through the roughness surface to delay the generation of the airflow separation, the purpose of improving the performance and efficiency of the fan and reducing the power required by the drive motor is achieved. Therefore, the heat dissipation fan of the present invention has the advantages of high efficiency, power saving, and the like. [Embodiment] The present invention discloses a cooling fan which uses a boundary layer control theory to design a rough seam based on a fan suction surface, so that it can be modified with the most economical advantages. The phenomenon that the boundary layer of the fan is peeled off, thereby improving the performance of the fan and improving the efficiency of the wind. In order to make the description of the present invention more detailed and more detailed, please refer to the following description and cooperate with Figure 3 to the first! Diagram of i diagram. In the axial flow cooling fan, in addition to its fan blade and wing theory, there is also a problem of air separation in the fan. Therefore, for the obsolete fan, in addition to the basic airfoil of the fan blade, the earth-grown earth, and the optimization of the blade angle of attack design, solving the phenomenon of air stripping T is also one of the ways to improve the performance of the fan. . In view of the above, the present invention provides a cooling fan that utilizes boundary layer control technology to effectively solve the airflow peeling phenomenon of the fan blade. "Monthly", FIG. 3, which is a schematic diagram of a fan rotor of a 71305810 political heat fan according to a preferred embodiment of the present invention. - ^ By the fan rotor 200, the cylinder is cool, and the heat is dissipated. The fan is mainly used to drive the fan rotor 200 by using a drive motor. The fan rotor is 2〇〇5 /丨 less ^; #4^孟中,古本户乂 has included the hub 202 and a plurality of blades 204, wherein The second fan blade 204 is engaged with the hub 202. The onboard + door Lu Xianyi is designed according to aerodynamic theory (4) 帛 2Q4 Auxiliary design (CAD) software to make an ancient test, use 1: brain J Huan body, will come out 3D stereo 2〇4' having a twist angle and connecting the blades 2〇4 to the structure of the hub 2〇2. The suction surface 2〇6 of the fan blade is provided with at least one rough region 212, wherein the rough & 212 includes a plurality of microstructures 2 〇 8. In the present invention, the microstructure 2 (10) may be a bump structure, such as the suction of the blade 2 () 4a shown in the figure f 4A from the bump set on 2Q6a, Or it may be a recessed structure, such as the recess 2_ provided on the suction surface 2〇6b of the fan blade shown in the first figure. As shown in Fig. 5, the micro junction Structure 2 〇8 can be a number of differently shaped structures, such as semi-circular/arc & 'the sector of the arc at the front end, the sector of the arc at the rear end c, the triangle d~f, or the rectangle §~匕. In the present invention, a rough seam zone 212 is required before the airflow separation point of the blade 204. Therefore, when the rough zone 212 is set, the computational fluid dynamics (cfd software) can be used to simulate the flow field condition of the fan rotor 200, and According to the simulation results, according to the characteristics of the test results of the fan rotor 200, it is analyzed whether the surface of the fan blade 2〇4 of the fan rotor 2 is stripped, and the airflow separation point D of the surface of the fan blade 2〇4 is obtained, for example, Figure 6. Next, the roughened zone 212 is disposed at least before the airflow separation point D of the suction face 206 of the blade 2〇4. In a preferred embodiment of the invention, the roughened zone 212 is provided at each The leading edge 210 of the blade 2〇4, that is, the microstructure 2 0 8 is arranged on the leading edge 21 of the blade 2 〇4, as shown in Fig. 3. However, as shown in Fig. 7. The fan rotor 3〇〇, the invention 1305810 can also be arranged on the surface of the suction surface of each blade 3〇4 The blades 3〇4 are joined to the wheel 3〇2. Please refer to FIG. 3 again. In the present invention, each piece is the same, and the hoist 1 ~ piece feathers 204 have airfoil The structure, that is, the fan blade 2〇4:face is airfoil' as shown in the figure. The rough zone 212 of the present invention is preferably disposed on the airfoil 畲' of the blade 204, 9 义 tongue _ heterogeneous center of gravity Before 214, that is, in the center of the fan blade 204. In one embodiment of the invention, the 'rough region 212 is packaged = circular bumps' and the microstructures are arranged in a single column two: the spacing between the structures (four) = : Two edges at 21°. The adjacent two micro-junctions are preferably substantially between .5 times and 1 times the official degree 218 of each microstructure 208, as shown in the figure. In addition, each:: the thickness of the structure 2〇8 222 is preferably the most airfoil structure of the blade 2〇4: thickness 220 # 〇·5 times or less 'better than the maximum thickness of the wing type 204 of the blade 204 is 0.1 times to 22° 〇_5 times, as shown in Figure 9; the above is only the embodiment of the present invention, the present invention is not (four): = zone: set before the air separation point of the blade to improve the boundary layer In addition to the peeling image, the position of the raw sugar region on the suction side of the blade of the present invention and the size and density of the microstructure can be adjusted according to the requirements of the fan and the product to be installed. In the present invention, the fan rotor 200 can be The fan blade 204 is integrally formed with the hub 202 for the integrally formed structure, wherein the fan rotor _ material can be plastic, and the fan rotation can be made by, for example, injection molding. When the ancient rotor fan is 2〇0' A mold can be used, wherein the mold can be provided with a roughened area in advance, so that suction can be obtained through the mold 1305810 on face 206 has blade 2〇4 of roughened zone 212. However, in other embodiments of the present invention, the mold for making fan rotor 200 may not be provided with a roughened area, and after the main structure of fan rotor 200 is completed, The roughening zone 212 is disposed on the suction surface 206 of the blade 2〇4 by using the processing method. The rough zone 212 is a post-processing structure. The suction surface 206 of the blade 204 has a rough structure of the microstructure 2〇8. 2丨2, so the turbulence phenomenon occurs when the airflow passes through the rough zone 212, so that the kinetic energy generated by the airflow passing through the rough surface can eliminate the velocity gradient of the suction surface 206 of the blade 2〇4, and can be delayed. Or improve the generation of the air separation point, thereby increasing the overall efficiency of the fan. After testing, it is found that under the same air volume, the input power of the cooling fan of the fan blade having the rough area of the present invention is smaller than that of the conventional fan'. Moreover, the efficiency of the cooling fan of the present invention is better than that of the conventional fan, as shown in Fig. 11. It can be seen that the cooling fan of the present invention can effectively improve the performance of the fan. The efficiency and the power consumption of the drive motor can be saved. It is obvious from the above preferred embodiments of the present invention that the heat dissipation fan of the present invention has roughness on the surface of the blade and uses the airflow to pass through the roughness surface. The generated kinetic energy delays the generation of the airflow separation. Therefore, the fan performance and efficiency can be effectively improved' and the required power of the driving motor can be reduced. Therefore, the cooling fan of the present invention has the advantages of high efficiency, power saving and environmental protection. According to a preferred embodiment of the present invention, another advantage of the present invention is that a fan blade having a rough region can be directly produced by an integrally formed injection molding technique, which is relatively easy to manufacture and has a cost advantage. After the main body of the leaf is formed, the roughening zone is set or modified on the blade by post-processing method, so that the performance of the fan can be improved immediately, and the applicability is good. 1305810 The present invention has been disclosed in a preferred embodiment as above: However, the present invention has any of ordinary skill in the art: from the spirit and scope of the present invention, Mj 4 乍 Various changes and retouching, so the protection of the month is defined by the scope of the patent application. [Simple description of the diagram]: 1 is a schematic diagram showing the fan rotor of a conventional cooling fan. 2 is a schematic diagram of a process of fan blade surface airflow separation. Figure 3 is a schematic view of a fan rotor according to the present invention. A preferred embodiment of a heat dissipation fan is shown in accordance with the present invention. A partial cross-sectional view of the fan-reading of the preferred embodiment. ',,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,, schematic diagram. The Fig. 5 is a schematic view showing the shapes of several microstructures of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 7 is a schematic view showing a fan rotor of another preferred fβ & fan according to the present invention. The schematic diagram of the Xiao Jia Guan canned heat dissipation wind is shown in the top view of the fan blade of the heat dissipation winder according to the preferred embodiment of the present invention. ..., fan Γ \ __ Figure shows a schematic cross-sectional view of a relatively thin fan blade in accordance with the present invention. The cooling fan of the preferred embodiment shows the cooling fan of the present invention and the conventional wind with a smooth surface. 11 I3〇58l〇 212 216 220 300 304 308 b :. d : Comparison of required power of the motor. 1 is a continuation of the comparison chart of the present invention. Cooling fan and traditional multi-piece symbol description: Fan rotor: Fan blade 102: Hub 106: Surface: Fan rotor: Fan blade: Fan blade 202: Hub 204a: Fan blade 206: Suction surface: Suction surface 206b: Suction surface: Microstructure 208a: Bump: Depression 210: Wing front edge rough wheel zone 2 14 : Airfoil center of gravity spacing 218: Width thickness 222: Thickness fan rotor 302: Hub blade 306: Suction surface phase rough zone 1 shape a: Semicircular /Arc c: Fan-shaped i-angle e: Triangle L-angle δ-shaped g: Rectangular wind 12