Because the prediction of coolant flow in the full-range performance calculation is an important feature of the present study, the variation of the fractional coolant flow is also plotted in Fig. 7. Note that the material of the air-cooled turbine nozzle is K4648Y, and the
corresponding maximum permissible temperature of 1173 K is used in the coolant requirement prediction. In the operation of a real engine, the coolant flow is automatically set by the matching between compressors, turbines and pressure drops, which varies with the engine load, and the values of the coolant flow must be checked in the design phase of the engine to ensure the temperature limit at both full-load and part-load. In the analysis results, as the engine load varies from 10% to 100%, the inlet temperature of the HP turbine are found to increase from 820 K to 1260 K; thus,cooling air is required at engine loads higher than 80% when the inlet temperature is higher than the maximum permissible temperature,and the amount of cooling air increases rapidly with the engine load. Note that the exact value of coolant flow rate can rarely be measured in an actual engine [30]; therefore, it is impossible to directly validate the predicted coolant flow. Nevertheless, because the amount of cooling air will significant alter the gas temperature and the engine efficiency, the coolant requirement prediction, or the hybrid cooling model in the present method, can be verified indirectly by the accurate prediction of engine efficiency and power-turbine gas temperatures, as in Figs. 8 and 10. In addition the coolant requirement prediction for the design-point condition will be further verified with a full three-dimensional conjugate heat transfer analysis in the following section.
เนื่องจากคาดเดาไหลลแลนท์ในการคำนวณประสิทธิภาพเต็มมีคุณลักษณะสำคัญของการศึกษาปัจจุบัน การเปลี่ยนแปลงของการไหลลแลนท์เศษจะยังลงจุดใน Fig. 7 โปรดสังเกตว่า วัสดุของหัวฉีดกังหัน air-cooled K4648Y และcorresponding maximum permissible temperature of 1173 K is used in the coolant requirement prediction. In the operation of a real engine, the coolant flow is automatically set by the matching between compressors, turbines and pressure drops, which varies with the engine load, and the values of the coolant flow must be checked in the design phase of the engine to ensure the temperature limit at both full-load and part-load. In the analysis results, as the engine load varies from 10% to 100%, the inlet temperature of the HP turbine are found to increase from 820 K to 1260 K; thus,cooling air is required at engine loads higher than 80% when the inlet temperature is higher than the maximum permissible temperature,and the amount of cooling air increases rapidly with the engine load. Note that the exact value of coolant flow rate can rarely be measured in an actual engine [30]; therefore, it is impossible to directly validate the predicted coolant flow. Nevertheless, because the amount of cooling air will significant alter the gas temperature and the engine efficiency, the coolant requirement prediction, or the hybrid cooling model in the present method, can be verified indirectly by the accurate prediction of engine efficiency and power-turbine gas temperatures, as in Figs. 8 and 10. In addition the coolant requirement prediction for the design-point condition will be further verified with a full three-dimensional conjugate heat transfer analysis in the following section.
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