| High gas turbine inlet temperatures can lead to safety problems in gas turbine components,and internal cooling channels are used to ensure that turbine blades operate within safe temperatures.One of the most important ways to improve the heat transfer performance of the cooling channels within the gas turbine blades is to improve the performance of the cooling channels.In the cooling channels,the ribs are the main influencing factor on the performance of the channels.By making effective and reliable design improvements to the ribs,the cooling efficiency of the internal channels can be effectively improved and has a significant potential for development.The paper uses numerical simulations for in the two-pass cooling channel to further improve the heat transfer performance by the innovative rib structure.The channel inlet Re ranges from 10,000 to 60,000,and compares the thermal performance index of the two-pass channel with the smooth channel to efficiently improve the cooling effect of the channel.The paper proposes a new type of petal-shaped rib in the two-pass channel to enhance the heat transfer and flow characteristics of the cooling channel in the turbine blade.The paper further optimizes the design on the basis of the petal-shaped ribs to gradually improve the cooling efficiency of the internal cooling channel.In addition,the paper investigates the heat transfer and flow characteristics of the ribbed channel in both stationary and rotating conditions.A design proposal to enhance the cooling efficiency of the channel in different conditions,aiming to improve the thermal performance of the channel step by step and reduce the turbine temperature to ensure safe engine operation.The paper also considers the influence of Re and analyzes the distribution of the temperature,pressure,turbulent kinetic energy and flow characteristics in cooling channel,and considers the heat transfer and friction coefficients of the channel.The performance of various ribbed channels is evaluated in the paper,and obtain the optimal parameters of the ribbed channel in static and rotating conditions.(1)The SST k-ω model is used to compare the thermal performance of petal-shaped rib,a-quarter-cylinder rib,and square ribs in static states.The results show that petal-shaped rib and a-quarter-cylinder rib have better heat transfer and flow performance than traditional square ribs.Curved surface can effectively increase turbulent kinetic energy and conducive to heat exchange to enhancing heat transfer in the channel.Nu is directly related to turbulent kinetic energy,and the larger turbulent kinetic energy,the larger Nu.The new petal-shaped rib provides the best cooling performance among the three ribbed channels by enhancing heat transfer and having the lowest pressure loss in the channel.The Nu of the petal-shaped rib is compared with that of the square rib,resulting in an increase of up to 21.14%,a decrease in f by 10.04%,and the η as high as 2.02.(2)Suitable pitch can balance the heat transfer and pressure loss of the channel and improve the thermal performance of the channel.Therefore,the study explores the optimal pitch of the petal-shaped rib.The ratio of rib pitch to rib height is studied,and petal-shaped rib channels with three pitches of p/e=5,p/e=8,and p/e=10 are designed.The results show that p/e=8 is the optimal pitch of the petal-shaped rib,and the Nu of p/e=8 is 3.57%-6.09% larger than that of p/e=10,and the f of p/e=8 is 9.72%-13.32% smaller than that of p/e=5.From the perspective of thermal performance,η of p/e=8 is 0.82%-4.22% higher than that of p/e=10.(3)The paper investigates V-shaped arrangements and angle size of the petal-shaped rib in the two-pass channel.The results show that the 60° V-shaped ribs effectively enhance the thermal performance of the two-pass channel and at the expense of less pressure losses.The heat transfer of 90° V-rib is better than 60° V-rib,the flowability of 60° V-rib is better than 90°V-rib and the η of 60° V-rib is better than 90° V-rib.Case 4 has the best thermal performance among the four V-rib arrangements,the η increases 20.56%-24.89% compared to Case2,and the η reaches 1.73-2.04.(4)The paper proposes a composite structure which combining low ribs and V-rib(60°Vshaped rib with p/e=8)to enhance two-pass channel heat transfer of V-shaped rib,and compares the three composite structures.The low ribs including fan-shaped rib,circular-shaped rib and calabash-shaped rib.The thermal performance of the three composite structures is compared with the solely V-shaped rib,aiming to explore the structure with the best thermal performance from the three composite structures to enhance the cooling efficiency of the turbine blade.The paper concludes that the composite structures augment the thermal performance compared the solely V-shaped rib,due to the setting of the low rib in the longitudinal depth of the V-shaped rib.It enhances the turbulent energy and destroyed the boundary layer,which enhances the heat transfer in the longitudinal depth of the V-shaped rib.The best thermal performance is the composite structure of the calabash rib.The composite structure of the calabash rib also has excellent flowability,which reduces pump power and economic cost.The Nu of the calabash rib composite structure increases by 4.33%-6.6% compared to the solely V-shaped rib,the calabash rib composite structure f is larger by 0.04%-4.48% compared to the solely V-shaped rib,and the calabash rib composite structure f reduces by 3.67%-5.21% compared to the fan rib composite structure.It concludes that the thermal performance index(η)of the composite structure is enhanced compared to the channel with solely V-shaped rib.The calabash rib composite structure has the best thermal performance,and the thermal performance index of the calabash rib composite structure improves by 4.16%-5.35% compared the solely V-shaped rib,and the maximum value of η reaches 2.13.(5)A numerical study of the rotating two-pass channel using Standard k-ε model has been carried out in this paper,and investigates the flow and heat transfer in the ribbed channel for 4parameters.The results show that rotation has a significant influence on the heat transfer in the two-pass channel.Rotation has an important influence on the thermal performance of the first channel,while it has a slight influence on the second channel,the heat transfer of the first channel is more augmentable than the second channel.The pitch with the best thermal performance is p/e=10.The 45° angled rib arrangement is preferable to the V layout in heat transfer,where the 45° angled rib enhances heat transfer of the channel and reduces the influence of rotation.p/e=10 petal-shaped rib improves Nu by 6.88%-10.22% compared the Vshaped rib,p/e=10 petal-shaped rib f is 5.62%-41.27% less than square rib channels,and p/e=10petal-shaped ribbed channel improves η over square ribbed channel by 5.48%-13.48%,and ηof the p/e=10 petal-shaped ribbed channel is 1.27-1.37.Hence,the 45° oblique ribbed channel with p/e=10 has the best thermal performance in the rotating channel. |
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