本文選題：渦輪葉片 + 內(nèi)冷結(jié)構(gòu)　； 參考：《西北工業(yè)大學(xué)》2015年博士論文

【摘要】：現(xiàn)代高溫燃?xì)鉁u輪葉片常用的冷卻結(jié)構(gòu)為內(nèi)外復(fù)合冷卻結(jié)構(gòu)。冷卻氣體在葉片內(nèi)部通道流動(dòng)吸熱后從氣膜孔噴出實(shí)施氣膜冷卻，因此葉片內(nèi)部結(jié)構(gòu)對外部氣膜冷卻有著重要的影響。但是，由于內(nèi)、外部流動(dòng)換熱機(jī)理有很大差別，因此，到目前為止，這兩部分的流動(dòng)換熱特性多是分開單獨(dú)進(jìn)行研究的。近年來，隨著設(shè)計(jì)要求的不斷提高，進(jìn)行葉片冷卻結(jié)構(gòu)精細(xì)化設(shè)計(jì)已成為趨勢，必須了解在不同內(nèi)部冷卻結(jié)構(gòu)下的氣膜冷卻特性，以便于在渦輪葉片設(shè)計(jì)中進(jìn)行準(zhǔn)確的熱分析。 為了研究內(nèi)冷結(jié)構(gòu)對外部氣膜冷卻特性的影響，本文分別建立了有內(nèi)冷結(jié)構(gòu)影響的氣膜冷卻特性實(shí)驗(yàn)系統(tǒng)和無內(nèi)冷結(jié)構(gòu)影響的氣膜冷卻特性實(shí)驗(yàn)系統(tǒng)。對于各實(shí)驗(yàn)結(jié)構(gòu)，建立了相應(yīng)的數(shù)值模擬計(jì)算模型，分析了各結(jié)構(gòu)下的流動(dòng)機(jī)理。關(guān)于內(nèi)冷結(jié)構(gòu)影響，文中主要分析了光滑內(nèi)冷通道內(nèi)部橫流、帶肋內(nèi)冷通道內(nèi)部肋角度與內(nèi)部肋位置三方面因素。 關(guān)于光滑內(nèi)冷通道內(nèi)部橫流的影響，文中主要對比分析了光滑橫流通道結(jié)構(gòu)與無內(nèi)冷影響的大腔進(jìn)氣結(jié)構(gòu)。研究表明光滑內(nèi)冷通道內(nèi)部橫流影響下氣流流動(dòng)結(jié)構(gòu)與大腔進(jìn)氣結(jié)構(gòu)有明顯不同：在氣膜孔進(jìn)口，部分內(nèi)部氣流會(huì)在沖擊氣膜孔壁面后向下流出氣膜孔，，使得氣膜孔進(jìn)口面積相對減��；在氣膜孔內(nèi)部，流線呈螺旋狀分布，其中貼壁處螺旋線的螺距較大，中間的螺距較��；氣膜孔出口，由于氣流螺旋狀流動(dòng)，會(huì)形成出口堵塞，并且使得氣膜孔出口射流分成兩股；在氣膜孔下游，兩股射流各自形成一組對轉(zhuǎn)渦，對氣膜冷卻效率與換熱系數(shù)分布產(chǎn)生較大影響。實(shí)驗(yàn)結(jié)果顯示：小吹風(fēng)比下，橫流越強(qiáng)，冷卻效率越低，大吹風(fēng)比下，橫流越強(qiáng)，冷卻效率越高；對于換熱系數(shù)，橫流越強(qiáng)，換熱系數(shù)越高；另外，內(nèi)部有橫流條件下，氣流需克服自身動(dòng)量旋轉(zhuǎn)一定的角度流入氣膜孔，在這一過程中出現(xiàn)較大的流動(dòng)損失，流量系數(shù)減小，橫流越強(qiáng)，氣膜孔流量系數(shù)越小。 關(guān)于帶肋內(nèi)冷通道內(nèi)部肋角度的影響，文中主要對比分析了135°肋橫流通道結(jié)構(gòu)與45°肋橫流通道結(jié)構(gòu)。研究表明，肋結(jié)構(gòu)的存在，使得通道內(nèi)部氣流發(fā)生強(qiáng)烈的二次旋流，不同的肋角度則導(dǎo)致了不同的二次旋流旋轉(zhuǎn)方向：在135°肋通道中通道上部分旋渦順時(shí)針方向旋轉(zhuǎn)，與氣膜孔傾斜方向相近，使得氣流較易流入氣膜孔；而45°肋結(jié)構(gòu)中，通道上部分旋渦逆時(shí)針方向旋轉(zhuǎn)，與氣膜孔傾斜方向相反，氣流更難流入氣膜孔。內(nèi)部旋流影響了氣膜孔進(jìn)口速度分布，135°肋結(jié)構(gòu)中法向速度高速區(qū)位于進(jìn)口左側(cè)，右側(cè)則出現(xiàn)負(fù)值區(qū)域，而45°肋結(jié)構(gòu)正好相反。不同的進(jìn)口速度分布導(dǎo)致了不同的孔內(nèi)流動(dòng)結(jié)構(gòu)與出口射流結(jié)構(gòu)：135°肋結(jié)構(gòu)下，小吹風(fēng)比下孔內(nèi)流線為直線并且出口射流也只有一股，大吹風(fēng)比下孔內(nèi)出現(xiàn)部分螺旋線同時(shí)出口射流略微分開成兩股；45°肋結(jié)構(gòu)下，孔內(nèi)為螺旋狀流線，類似于光滑橫流通道結(jié)構(gòu)，出口速度分布與出口射流結(jié)構(gòu)也比較類似。不同的肋角度下出口射流結(jié)構(gòu)不同，影響了對應(yīng)的耦合渦結(jié)構(gòu)，導(dǎo)致了不同的氣膜冷卻效率與換熱系數(shù)分布。實(shí)驗(yàn)結(jié)果顯示：對于基礎(chǔ)圓柱孔型，小吹風(fēng)比下135°肋結(jié)構(gòu)下冷卻效率最高，大吹風(fēng)比下兩種肋結(jié)構(gòu)的冷卻效率均低于光滑橫流通道結(jié)構(gòu)，對于帶展向偏角的圓柱孔型，在各吹風(fēng)比下45°肋結(jié)構(gòu)的氣膜冷卻效率均為最高；關(guān)于換熱系數(shù)，兩種氣膜孔型下均表現(xiàn)為135°肋結(jié)構(gòu)下的換熱系數(shù)較低，45°肋結(jié)構(gòu)下的換熱系數(shù)較高；關(guān)于氣膜孔流量系數(shù)，135°肋結(jié)構(gòu)下流量系數(shù)最高，45°肋結(jié)構(gòu)下流量系數(shù)最低。 關(guān)于帶肋內(nèi)冷通道內(nèi)部肋位置的影響，文中主要對比分析孔在肋后，孔在肋中和孔在肋前三種結(jié)構(gòu)。隨著氣膜孔與肋位置相對向后移動(dòng)，從靠近前一個(gè)肋（孔在肋后）到靠近后一個(gè)肋（孔在肋前），進(jìn)入氣膜孔的氣流在通道內(nèi)形成的旋流逐漸減少，在氣膜孔進(jìn)口截面的旋流相應(yīng)減弱，進(jìn)口堵塞減小，孔內(nèi)速度分離略有減少，對應(yīng)的氣膜孔流量系數(shù)略有增大。在兩種肋角度下，肋位置改變時(shí)氣膜孔出口射流結(jié)構(gòu)均無明顯變化，因此下游氣膜冷卻效率與換熱系數(shù)分布也基本一致。 在研究光滑內(nèi)冷通道內(nèi)部橫流和帶肋內(nèi)冷通道內(nèi)部肋角度影響時(shí)，文中分別分析了基礎(chǔ)圓柱孔型和帶展向偏角的圓柱孔型。對比兩種圓柱孔型的實(shí)驗(yàn)結(jié)果可以發(fā)現(xiàn)：在相應(yīng)的四種內(nèi)冷結(jié)構(gòu)下，帶展向偏角的圓柱孔型的流量系數(shù)均高于基礎(chǔ)圓柱孔型；而關(guān)于氣膜冷卻效率，在無內(nèi)冷結(jié)構(gòu)與45°肋結(jié)構(gòu)下，帶展向偏角的圓柱孔型的氣膜冷卻效率高于基礎(chǔ)圓柱孔型，但是在光滑橫流通道結(jié)構(gòu)與135°肋結(jié)構(gòu)下氣膜效率卻低于基礎(chǔ)圓柱孔型。因此，為了保持帶展向偏角的圓柱孔型的高流量系數(shù)并改進(jìn)氣膜冷卻效率，文中關(guān)于帶展向偏角的圓柱孔型作出了三種改型方案：1）在氣膜孔出口沿展向偏斜方向使用圓柱孔型擴(kuò)張；2）在氣膜孔出口沿X方向使用圓柱孔型擴(kuò)張；3）綜合前兩種擴(kuò)張形式。結(jié)果發(fā)現(xiàn)，改型3既能增強(qiáng)氣膜展向覆蓋，還能延緩冷卻效率沿流向的下降速度，使得氣膜冷卻效率大幅上升。針對最佳改型（改型3），實(shí)驗(yàn)測量了其在光滑橫流通道結(jié)構(gòu)下的氣膜冷卻特性。結(jié)果表明，該改型在各實(shí)驗(yàn)工況下均能保持很好的氣膜覆蓋，與原帶展向偏角的圓柱孔型相比，冷卻效率增幅達(dá)到100%以上；同時(shí)，由于出口擴(kuò)張，該孔型的流量系數(shù)略高于基本的帶展向偏角的圓柱孔型。
[Abstract]:The cooling structure commonly used in modern high temperature gas turbine blades is internal and external cooling structure. The cooling gas is ejected from the air film hole after the flow of the inner passage of the blade. Therefore, the internal structure of the blade has an important influence on the external film cooling. So far, the flow and heat transfer characteristics of the two parts are studied separately. In recent years, with the continuous improvement of the design requirements, the fine design of the blade cooling structure has become a trend. It is necessary to understand the characteristics of the film cooling under different internal cooling structures so as to facilitate the accurate thermal separation in the design of turbine blades. Analysis.
In order to study the influence of internal cooling structure on the cooling characteristics of external gas film, the experimental system of air film cooling characteristics with internal cooling structure and an experimental system of air film cooling characteristics without internal cooling structure were established respectively. As for the influence of internal cooling structure, the three aspects of the internal flow in the smooth internal cooling channel, the rib angle inside the cold channel and the internal rib position are analyzed.
It is shown that the structure of smooth crossflow channel and the large cavity inlet structure without internal cooling are mainly compared and analyzed in this paper. It is shown that the flow structure of the smooth internal cooling channel is obviously different from the large cavity intake structure under the influence of the internal cross flow in the smooth inner cooling channel. The inlet area of the membrane hole is down and the inlet area of the gas film hole is reduced relatively. In the air film hole, the flow line is spirally distributed, in which the spiral distance of the spiral line at the wall is larger and the middle pitch is smaller. The exit of the gas film holes will form the outlet blockage, and the gas film hole outlet jets are divided into two strands. The two ply jets formed a group of opposite vortices on the downstream of the gas film hole, which had a great influence on the cooling efficiency and the distribution of heat transfer coefficient. The experimental results showed that the stronger the cross flow, the lower the cooling efficiency, the stronger the cross flow, the higher the cooling efficiency, and the higher the heat transfer coefficient, the higher the heat transfer coefficient, the higher the heat transfer coefficient was, the higher the heat transfer coefficient was, the higher the heat transfer coefficient was, the higher the heat transfer coefficient was, the higher the heat transfer coefficient, the higher the heat transfer coefficient; In addition, under the transverse flow condition, the air flow needs to overcome its momentum rotation and flow into the gas film hole. In this process, there is a larger flow loss, the flow coefficient decreases, the transverse flow is stronger and the flow coefficient of the gas film hole is smaller.
With regard to the influence of the internal rib angle of the inner ribbed inner ribs, the structure of the 135 degree rib crossflow channel and the cross flow channel of the 45 degree rib is mainly compared and analyzed. The study shows that the existence of the rib structure makes the airflow inside the channel strong two swirling flows, and the different rib angles lead to the different rotation direction of the two swirl flow: in the 135 degree rib channel. The part of the vortex in the middle channel rotates clockwise and is close to the inclined direction of the air film hole, which makes the air flow easier to flow into the gas film hole. In the 45 degree rib structure, the part of the vortex rotates in the direction of the clockwise direction, and the air flow is more difficult to flow into the gas film hole. The internal swirling flow affects the velocity distribution of the air film hole and the structure of the 135 degree rib. The middle and high velocity region is located on the left side of the inlet, and the negative region appears on the right side, while the 45 degree rib structure is just the opposite. The different inlet velocity distribution leads to the different flow structure and the outlet structure of the outlet. Under the 135 degree rib structure, the small blow air is a straight line in the lower hole and the outlet jet is only one, and the large blow is more than the lower hole. At present, some spiral lines are at the same time the outlet jet is slightly differential into two strands; under the 45 degree rib structure, the hole is spiral flow line, similar to the smooth crossflow channel structure. The velocity distribution of the outlet is similar to that of the outlet jet structure. The different outlet jets under different rib angles affect the corresponding coupling vortex structure and lead to different air film cooling. Efficiency and heat transfer coefficient distribution. The experimental results show that for the foundation cylindrical pass, the cooling efficiency is the highest under the smaller blow ratio under the 135 degree rib structure, and the cooling efficiency of the two rib structures under the large blowing ratio is lower than the smooth crossflow channel structure. For the cylindrical pass with the spread angle, the air film cooling efficiency of the 45 degree rib structure at each blow ratio is both. For the highest heat transfer coefficient, the heat transfer coefficient under the 135 degree rib structure is lower and the heat transfer coefficient is higher under the structure of the 45 degree rib under the structure of the two kinds of gas film, and the coefficient of flow rate of the gas film hole is the highest and the coefficient of the flow rate under the 45 degree rib is the lowest.
With regard to the influence of the internal rib position of the inner ribbed inner ribs, the paper mainly contrasts and analyses the three structures of the hole in the rib and the front of the ribs after the ribs. As the gas film hole and the rib position move backward relatively, from the front of the front ribs (after Kong Zailei) to the next rib (the hole is before the ribs), the flow of air flow into the air film hole in the channel is driven by the swirl in the channel. Gradually decreasing, the swirling flow of the inlet section of the gas film hole decreases correspondingly, the inlet blockage decreases, the velocity separation in the hole decreases slightly, and the corresponding gas film pore flow coefficient increases slightly. At the two rib angle, there is no obvious change in the outlet jet structure of the gas film hole at the change of the rib position, so the distribution of the cooling efficiency and heat transfer coefficient of the downstream gas film is also basically the same. Cause.
In the study of the internal cross flow of the smooth inner cooling channel and the internal rib angle in the inner ribbed cold channel, the cylindrical pass and the circular hole with the spread angle are analyzed in this paper. The experimental results of the two kinds of cylindrical holes can be found that the flow coefficient of the cylindrical pass with the spread angle is high under the corresponding four internal cooling structures. For the air film cooling efficiency, the air film cooling efficiency of the cylindrical pass with the uncooled structure and the 45 degree rib structure is higher than that of the foundation cylindrical pass, but the film efficiency under the smooth crossflow channel structure and the 135 degree rib structure is lower than that of the base circular cylinder. The high flow coefficient of the column pass and the improvement of the cooling efficiency of the gas film are made. In this paper, three modification schemes are made about the cylindrical hole with the spread angle. 1) the expansion of the cylindrical hole is used in the outlet of the gas film hole along the direction of deflection; 2) the expansion of the cylindrical pore in the X direction of the gas film hole; 3) the two forms of expansion. The type 3 can not only enhance the covering of the air film spreading, but also delay the cooling efficiency along the flow direction and increase the cooling efficiency of the gas film. The film cooling characteristics under the smooth crossflow channel structure are measured by the experiment. The results show that the film can keep a good film cover under the experimental conditions. Compared with the cylindrical pass with spreading angle, the increase of cooling efficiency is up to 100%. At the same time, the flow coefficient of the pass is slightly higher than that of the cylindrical pass with the spread angle.

【學(xué)位授予單位】：西北工業(yè)大學(xué)
【學(xué)位級別】：博士
【學(xué)位授予年份】：2015
【分類號】：V235.1

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