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Study of Heat Exchange in Cooling Systems of Heat-Stressed Structures

机译：热应力结构冷却系统中热交换的研究

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Increasing working parameters of the cycle of gas-turbine engines, complicating design of gas-turbine plants, as well as growing aerodynamic, thermal, static, and dynamic loads, necessitate the development of promising cooling systems for heat-stressed structures. This work is devoted to an experimental study of heat exchange in ducts equipped with systems of inclined and cross walls (fins). It has been found that an increase in the Reynolds number Re from 3000 to 20000 leads to a decrease in the heat exchange, which is characterized by the relative Nusselt number Nu, by 19-30% at the angle of inclination of the walls φ = 0, 40°, 50°, and 90° if the length of the walls x_w is comparable to the spacing b_s and by 12-15% at φ = 30° and 90° if x_w ≫ b_s. If cross walls are used in cooling ducts, the length of the walls x_w plays the governing role; an increase in this characteristic from 1.22 x l0~(-3) to 3.14 x 10~(-3) m leads to an increase in the intensity of heat exchange by 30-40% and to a decrease in the capacity of the entire system of the walls. It has been shown that, on surfaces with wavy fins, the intensity of heat exchange is closest to that determined in the models under study. For example, values of the Colborne criterion StPr~(2/3) for ducts equipped with wavy fins and for the models under study differ only slightly (by 2-20% depending on the value of the angle φ). However, the difference for surfaces with short plate fins and ducts equipped with inclined walls is high (30-40%). This is due to the design features of these surfaces and to the severe effect of the inlet portion on heat exchange, since the surfaces are characterized by a higher ratio of the duct length to the hydraulic diameter L/d_h at small fin thicknesses ((0.1 -0.15) x 10~(-3) m). The experimental results can be used in developing designs of nozzle and rotor blades of high-temperature gas turbines in gas-turbine engines and plants.
机译：燃气涡轮发动机循环工作参数的增加，燃气涡轮设备设计的复杂化以及空气，热，静态和动态载荷的不断增长，都需要为热应力结构开发有希望的冷却系统。这项工作致力于在装有倾斜和横壁（散热片）系统的管道中进行热交换的实验研究。已经发现，雷诺数Re从3000增加到20000会导致热交换的减少，其特征在于相对努塞尔数Nu在壁的倾角φ＝ 19-30％。如果壁的长度x_w与间距b_s是可比的，则为0、40°，50°和90°；如果φ= 30°，壁的长度x_w可与间距b_s相比较；如果x_w≫ b_s，则在φ= 30°时为12-15％。如果在冷却风道中使用横壁，则壁长x_w起主导作用。此特性从1.22 x l0〜（-3）增加到3.14 x 10〜（-3）m导致热交换强度增加30-40％，并导致整个系统的容量下降的墙壁。已经表明，在具有波浪状翅片的表面上，热交换的强度最接近所研究模型中确定的强度。例如，配备波纹状鳍片的风管和所研究模型的科尔本准则StPr〜（2/3）的值仅略有不同（取决于角度φ的值相差2-20％）。但是，带有短板翅片和带有倾斜壁的管道的表面的差异很大（30-40％）。这是由于这些表面的设计特征以及入口部分对热交换的严重影响所致，因为在较小的翅片厚度下，这些表面的特征是管道长度与水力直径L / d_h的比率更高（（0.1 -0.15）x 10〜（-3）m）。实验结果可用于开发燃气轮机和工厂中的高温燃气轮机的喷嘴和转子叶片的设计。

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