Research On Flow Mechanism And Blade Design Technology Of The Novel Low Solidity Tip-turbine

Research group proposed a novel additional ducted fan structure can solve SSMI (Spool-Speed Mismatching Issue) well, and the core components tip-turbine of the novel power system has the double characteristics of low solidity and low aspect ratio, solidity can be as low as 0.6, aspect ratio as low as 0.4. The flow mechanism and the design technology of the tip-turbine did not form relatively perfect theory system. The novel additional ducted fan structure principle prototype based on the numerical simulation method was adopted to carry out the research of low solidity tip-turbine flow characteristic and its design technology, and laid the theoretical foundation for the subsequent development of new high bypass ratio propulsion vehicle. The main work is as follows:1?Based on the propulsion power concept of the novel additional ducted fan, the technical characteristics of additional ducted fan were analyzed, and the numerical research was carried out on the core component of tip turbine, further analyzing the aerodynamic characteristics and work mechanism of low solidity tip-turbine. As a result of that, The reduction of solidity will cause the throat position to migrate, which leads to a substantial decrease in the flow deflection and the acceleration of the expansion; The gap leakage loss caused by the low aspect ratio is 2 times larger than that of the original, and the influence of leakage vortex is gradually extended to the vicinity of the root of the blade, which reduce the effective extraction of energy area and the energy extraction rate greatly; For the novel power system, effective extraction of energy region and energy extraction rate is proposed to measure the specific work of tip-turbine qualitatively and quantitatively.2?Researching on low solidity forward-loading blade design technology, and the maximum displacement curve in leaf type and leaf root diameter in front of two factors to analyze the cascade throat position and radial pressure change on the flow field and performance of tip-turbine. The results reflects, when the maximum displacement curve in leaf type is located on the front leading edge, the throat can be trapped in the flow passage, which greatly improve the ability of airflow expansion and acceleration; when the leading edge diameter is suitable, the radial pressure difference can be reduced ,which can relieve mixing of tip leakage vortex and root uplifting low energy vortex to reduce flow loss. Finally, when the maximum displacement curve in leaf type is 10% axial position and the front blade root diameter is 1.5mm, low solidity tip-turbine performance best, compared to the original leaf type, the efficiency increased by about 3%.3?To explore the application effect of tandem cascade technology in the low solidity tip-turbine and focus on the research of energy extraction and influence work performance by changing the tandem cascade circumferential position and axial coincidence degree. The tandem cascade circumferential offset is 0.8t and the axial coincidence degree is 0, which is the best performance.Compared with the single row low solidity cascade, the best scheme of energy extraction rate increased by 8%, the extraction rate of reference value reaches 0.92, and the outlet section can effectively improve the area proportion increased to more than 90%. The best scheme can achieve a low solidity tip-turbine performance comparable to conventional turbines.