Research On The Leading Edge Skewed-Swept Rotor With Meridian Acceleration And Passage Structure

With the development of national economy and the harsh energy and request of the environment, higher and higher performance requests, such as wider operating range, high efficiency, has been put forward to the design of turbomachinery. Use the blade Skewed-Swept rationally can cause redistribution the pressure coefficient and control the development of the secondary flow; reduce the conglomeration of the low-momentum fluid near the wall region, by which we can reach the aim of improving the aerodynamic characteristic of the turbomachinery. The thesis proposes and constructs a new blade design system, which combine the conventional design system with CFD three-dimension flow calculation, based on the former quasi-three-dimensional design method by applying the theory of sweep aerodynamics. This system is used to design a new kind of controlled endwall flow blade. And the new blade is also used in the design and researching of meridian accelerated rotor and stator. At the same time, this thesis takes the three-dimensional viscous CFD analyses and aerodynamic characteristic experiment to investigate the efficient method of improving the stall margin of fans and compressors. With the comparison of aerodynamic characteristic and internal flow field between leading edge skewed-swept rotor and base rotor, the thesis proved the reliability of the design of leading edge skewed-swept blade. The internal flow phenomena of the leading edge skewed-swept blade, which reduced and restrained the endwall boundary, are theoretically analyzed. The thesis put forward the compound design method, including the use and realize of the virtual-equivalent velocity triangle diagram and the one-seventh boundary layer rule. The part of first design utilized NACA profile test data and the Schlichting theoretical correcting methods to modify base rotor. The part of second design is based on the skewed-swept blade-molding of annulus wall boundary layer model and the one-seventh boundary layer rule. It calculated and confirmed the skewed angle and swept angle, used the RBF Neural Network algorithm to reconstruct the blade surface according to velocity distribution and used the rational Bezier method to take the smooth deformation. This article also adapted and modified the relevant program of designing & calculation and of interface program and formed the design system of leading swept axial fan with meridian acceleration -FIDS2004. A new rotor with new blade which was designed by the realized FIDS2004 system, have the following four characteristics: the leading edge is skewed and swept near the hub and casing wall region; Adding a front curve to the leading edge based on the forward-swept; the trailing edge is forward-swept slightly, and taking the skewing at the root of the trailing edge; the direction of the trailing edge camber line is consistent with the routine blade shape, namely the exit metal angle of blade is not changed. The thesis given to innovations on reconstruction of blade, which realized the application of the RBF Neural Network algorithm to the reconstruction of leading edge skewed-swept rotor blade surface. Through the analysis of the result of fitting for the three dimension blade surface shape, it showed that the application of reconstructed three dimension blade surface has the high efficiency and accuracy because of the advantage of high speed of convergence and the access to globally optimal solution of the RBF network. This method provided a new way to solve the reconstruction of three-dimension blade surface. This article uses the rational Bezier curve/surface function in designing of blade molding texturing. By setting the control point of blade molding rationally according to the method of rational Bezier fitting, we ensure the aerodynamic characteristic of the blade's camber line and thickness, est. while realizing the smooth deformation of blade surface. The author developed the test-system for measuring fan performance, which is full automatic and high accurate. This article discussed the auto-controlled and tested system. For the first time it put forward and realized the expert-Fuzzy PID control system, which is applied to the research of fan. Applying the test system controlled by this special system we can make the better result. It has the high stability and swiftness. And it shortens the experiment time by 30% compared with the conventional test system. The system of internal flow field measure is formed by combined the flow rate test system with the system of DPIV speed test. We observed the phenomenon of tip vortex flow phenomenon when we took the internal test work of axial fan, which provide analyses of internal flow phenomena with the test data. By comparing the result of DPIV test and the result of CFD calculation, it showed the consistency of these two. The CFD tools of the research are commercial CFD software, namely Fluent. When we took the numerical analysis of leading edge skewed-swept rotor with meridian acceleration internal flow in design load and low flow rate ,and compared it with base rotor, it showed the flow mechanism of leading skewed-swept rotor: the skewed-swept rotor avoid backflow on base rotor leading edge, of low energy fluid annulus wall was entrain into main flow of blade mid-span,weaken the low energy fluid aggregation on annuluswall,decreased flow loss and blockage. The simulation results show that,the trailing wake of leading edge skewed-swept rotor was smaller than that of the base rotor, the influence of casing and (hub), restrain low energy fluid stack, enlarge the stall margin. The research proved improving internal flow status of fan by using leading skewed-swept and the validity and propriety of the design of the leading edge skewed-swept rotors are confirmed. The numerical simulation and analyses showed the internal flow atlas of blade diffuse and volute, revelation second flow characteristic that low energy flow on annulus wall if cursing blade with an advantageous "C-shape"distribution of static pressure coefficient was involved into main flow and flow rotor downstream. The application that axial spiral volute turn around the flow of rotor exit gives out new design ways of decrease duct resistance loses. It is supported by the National Natural Science Foundation of China (No: 50176012 ) and the Doctorate Foundation of the Ministry of Education(No: 20020487025)...