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51.
离心泵叶轮参数对进口回流的影响 总被引:3,自引:0,他引:3
本文对不同叶片进口角、叶片数、不同叶顶间隙的开式和闭式离心叶轮共12种叶轮的进口流场和回流发生情况进行了探针的动态测试和可视化观察.弄清了上述叶轮参数对进口回流初始流量和进口流场的影响. 相似文献
52.
Effects of multiple blade interaction on the containment of blade fragments during a rotor failure 总被引:12,自引:0,他引:12
A finite element analysis is used to study the impact and the containment aspects of rotor blade fragments that are produced during a aircraft jet engine rotor failure. The impact and containment studies are performed on a ring-type containment structure and various fragment types are considered in this study. For each type of fragment, the ring thickness is varied incrementally and the ring response, residual kinetic energy level of the fragments, magnitude of impact forces and the overall containment or failure are determined. First, only a single fragment is considered and the rotor is assumed to contain no other blades. Next, the remaining blades are introduced and the effects of multiple collisions with the other blades on the containment are analyzed. The explicit, nonlinear finite element code Dyna3d is used for the numerical computations in this study and the results are compared with the experimental results performed on a T58 rotor at the spin facility of the Naval Air Propulsion Test Center. 相似文献
53.
有扰流柱的复合倾斜式气膜冷却导向叶片换热特性的研究 总被引:1,自引:0,他引:1
本文采用试验方法研究复合倾斜式涡轮导向叶片的内换热特性。针对有无扰流柱、有无气膜孔以及三种不同直径的节流孔的模型进行了试验研究,获得了扰流柱、气膜孔以及180°弯的节流板孔径的变化对其内换热特性的影响,并得到了一些换热准则方程,从而获得了加强叶片内部换热的方法。 相似文献
54.
Erwin Lutwak 《Geometriae Dedicata》1997,66(1):119-124
The aim of this note is to strengthen and generalize an inequality of Sangwine–Yager regarding means of various quantities associated with the simplices circumscribing a convex body. 相似文献
55.
Joshua Cooper Benjamin Doerr Tobias Friedrich Joel Spencer 《Random Structures and Algorithms》2010,37(3):353-366
Jim Propp's rotor–router model is a deterministic analog of a random walk on a graph. Instead of distributing chips randomly, each vertex serves its neighbors in a fixed order. Cooper and Spencer (Comb Probab Comput 15 (2006) 815–822) show a remarkable similarity of both models. If an (almost) arbitrary population of chips is placed on the vertices of a grid ?d and does a simultaneous walk in the Propp model, then at all times and on each vertex, the number of chips on this vertex deviates from the expected number the random walk would have gotten there by at most a constant. This constant is independent of the starting configuration and the order in which each vertex serves its neighbors. This result raises the question if all graphs do have this property. With quite some effort, we are now able to answer this question negatively. For the graph being an infinite k‐ary tree (k ≥ 3), we show that for any deviation D there is an initial configuration of chips such that after running the Propp model for a certain time there is a vertex with at least D more chips than expected in the random walk model. However, to achieve a deviation of D it is necessary that at least exp(Ω(D2)) vertices contribute by being occupied by a number of chips not divisible by k at a certain time. © 2010 Wiley Periodicals, Inc. Random Struct. Alg., 2010 相似文献
56.
Abstract Flow through a blade trailing edge passage has been experimentally investigated in this article. This rectangular passage is divided into two channels by either a straight or a 120° wavy partition. Fluid in the first channel was injected into the second channel via 14 openings (holes) distributed uniformly and in the crests and troughs for the wavy configuration. Particle image velocimetry and a charge coupled device camera were used in experiment, with Reynolds number varying from 1,800 to 6,700. Experimental results show that the wavy configuration produces an oscillation flow in the second channel. The cause for the oscillation may due to the 120° wavy partition causing shear-layer instabilities and the formation of spanwise eddies by the wavy board. Pictures from the charge coupled device camera revealed strong mixing in the trailing edge, and this mixing could enhance heat transfer, which was confirmed in previous research. The amplitude of oscillation depends on Reynolds number and hole positions. It was observed that the injection flow was not symmetric to the openings, and it was skewed to the direction of the first channel main flow. The ratio of flow rate through the outlet and the bleeding holes was from 1:1 to 1:3. 相似文献
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Screw rotors play a crucial role in the performance of compressors. For the large-batch production of small- or medium-sized rotors, continuously rotor hobbing or grinding may be more efficient than form machining. In this study, a general mathematical model was developed for the generating machining of screw rotors with a worm-shaped tool. A two-parameter enveloping theory was applied to simulate the cutting process as the tool conducts polynomial feed motion considering its cutting edge. The normal errors of the generated cutting lines were computed and presented on the rotor tooth surface topologies to show the correctness and practicability of the proposed model. 相似文献