Research On Characteristiscs Of Temperature Reduction And Flow Resistanceof Pre-swirl System

With the cycle parameter of aeroengine goes high, the condition of hot section parts is getting extremely crucial, which becomes a hugh burden of secondary air system and cooling technology, and cooling air temperature rises as pressure ratio of compressor goes up, which meant the hot section need more coolant to cool down, that will decrease thrust weight ratio or power weight ratio. Under this condition, it is necessary to do research on pre-swirl technology to improve the quality of coolant. Air is forced to expand through the pre-swirl nozzle to achieve greater circumferential velocity and to turn its flow direction identical with rotor downstream, the velocity relative to rotor will be lower and temperature will get down, then the relative total temperature of air will be lower, which makes the quality of coolant improved.The thesis presents investigation on three aspects:Researches have been carried out on characteristics of temperature reduction and flow resistance of 3 kind of pre-swirl system. By means of model experiment on axial direct-transfer pre-swirl system, the rules of influences of non-dimensional flow rate and rotational reynolds number on cooling air temperature reduction and flow resistance were achieved. flowfield inside pre-swirl system was analyzed. Numerical simulations were carried out on simplified cover-plate pre-swirl system, flowfield was analyzed and influences of flow parameters versus pre-swirl temperature reduction and flow losses were achieved. Flow features in rotor-stator cavity, receiver hole and rotating cavity were summarized. Model experiments and computational research were carried out on radial pre-swirl system in various operating conditions, Each argument’s changement inside the path was summarized. Significant structure parameters, such as radial location of pre-swirl nozzle, pre-swirl angle and receiver hole area, effects on pre-swirl of coolant were acquired. The rules of influences of non-dimensional flow rate and rotational reynolds number on cooling air temperature reduction and flow resistance performance were achieved. Based on these researches, influences of structure parameters of pre-swirl nozzle and receiver hole on temperature reduction and flow resistance performances were investigated.Receiver hole is an important component of cover-plate pre-swirl system. To definite influences of receiver hole structure parameters on temperature reduction and flow resistance performances, under specified operating condition, various structure parameters of the receiver hole were investigated, and flow pattern inside and nearby the receiver holes were obtained. Physical interpretation of influences of receiver hole on pre-swirl effects was discussed. To improve the accuracy of one-dimension calculation, circumferential velocity ratio model of receiver hole was constructed and fixed in one-dimension calculation program. Compared with original method, calculation accuracy was improved by utilization of this model.Explorations on improvement of axial direct-transfer pre-swirl system and radial pre-swirl system were also achieved. In order to enhance heat transfer in low-radii of rotor, a direct-transfer pre-swirl system with two rows of nozzles was investigated, results show that the heat transfer is enhanced for the very arrangement, it is lower the the average temperature of rotor surface near the low-radii. Based on radial pre-swirl system, deflector vanes were fixed in co-rotating cavity, which makes a new radial pre-swirl system, and characteristics of temperature reduction and flow loss were studied. Numerical simulations were carried out both original and with vanes models, flow field were obtained, reasons of gaining more temperature reduction for new model were summed up. Geometrical parameters of deflector vanes, such as number, length, location, etc, were investigated. The experimental result shows that the model with vanes get more temperature reduction indeed under the same circumstance.