The intent of this article is to describe recent experimental findings relative supersonic nozzle mixer ejector performance. Such ejectors are a candidate means reduce jet noise commercial aircraft during takeoff and landing. concept involves the introduction an array large-scale, low-intensity streamwise vortices into downstream mixing duct, which enhances through inviscid stirring process. This results in increased pumping performance more completely mixed flows exiting shroud. Past...

The broad range applications of Ultra-Fine Grained metals is substantially limited by the lack a welding method that allows them to be joined without losing strong refinement structure.From this point view, solid state processes are privileged.Friction tests were carried out on UFG 316L stainless steel.A joining process at high temperature activates recrystallization, therefore friction parameters selected according criterion lowest degree weakness due recrystallization in heat affected...

Forced mixer lobes in augmentor primary ejectors obtain a 100-percent increase pumping over conventional design, together with nearly complete mixing very short ducts, through the generation of large scale axial vorticity duct. The causes rapid and secondary flows low losses; since length is minimized, wall friction losses are reduced, allowing more flow to be pumped for given total pressure flow. Analytical results presented that judged have significant implications future ejector test work.

where power is either added (e.g., for propulsion) or extracted wind/water turbines.) The formulation first principles based, free of empiricisms, overcomes past limitations, and uncovers heretofore unknown high performance potential such systems. For shrouded props, these new control-volume based predictions are shown to agree well with both independent experimental computational data, as other analytical empirical models. Solutions generally involve simple polynomials a single input...

Older commercial aircraft often exceed FAA (Federal Aviation Administration) sideline noise regulations. The major problem is the jet associated with high exhaust velocities of low bypass ratio engines on such aircraft. Mixer/ejector systems can provide a simple means reducing these by mixing cool ambient air velocity engine gases before they are exhausted to ambient. This paper presents new information thrust performance predictions, and augmentation capabilities mixer/ejectors. Results...

In dies for cold extrusion permissible internal pressure may be increased by the use of one or two shrink rings. Such design creates tensile stresses in ring and compressive insert. The essentially boils down to define diametrical interference fit attained during assembly. Interference determines properties die must carefully selected. There are basically methods design: based on Lame’s solution FEM. None these include roughness interface surfaces ring. pre-stressed micro-die shows that...

Etude de la reduction trainee forme due au decollement couche limite dans les regions bord fuite. Application aux profil aerodynamiques des conditions grande portance

The use of ultrasonic assistance in microforming is becoming more and popular. Mainly due to the beneficial effect vibrations on flow plastic deformation reported already 50s last century. influence two types: surface volume. mainly reduction friction forces, volumetric impact dislocation movement even phase transitions. work focuses dynamic aspect vibration assisted microforming. at a frequency 20 kHz an amplitude 16 µm, micro-upsetting process aluminum sample resulted high concentration...

Permissible internal pressure in dies for cold extrusion may be increased by the use of one or two shrink rings. The design essentially boils down to defining diametrical interference fit die/ring assembly. There are methods design: analytical based on Lame's solution and numerical finite element modelling (FEM). None these includes roughness interface surfaces die insert ring. However, when designing pre-stressed micro-dies, cannot disregarded classical diameter must corrected. In this...

Views Icon Article contents Figures & tables Video Audio Supplementary Data Peer Review Share Twitter Facebook Reddit LinkedIn Tools Reprints and Permissions Cite Search Site Citation Wojciech Presz, Robert Cacko; Influence of Micro‐Rivet Manufacturing Process on Quality Micro‐Joint. AIP Conf. Proc. 4 May 2011; 1353 (1): 541–546. https://doi.org/10.1063/1.3589571 Download citation file: Ris (Zotero) Reference Manager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search...

The electrical connectors mostly have silver contacts joined by riveting. In order to reduce costs, the core of contact rivet can be replaced with cheaper material, e.g. copper. There is a wide range commercially available bimetallic (silver-copper) rivets on market for production contacts. Following that, new conditions in riveting process are created because bi-metal object riveted. analyzed example, it small size object, which placed border microforming. Based FEM modeling load different...

Miniaturisation generates necessity of micro‐parts production. Micro‐scale means closer tolerances and better surface roughness. These requirements can be achieved with metal forming processes but under high pressure sufficient relative sliding distance between tool workpiece surface. It makes such process galling prove. This tendency increases diminishing component dimensions. Literature search previous investigations shows that implementation vibrations might a solution for limitation in...

The demand for very small metal parts is growing rapidly due to the development of micromechanisms. In microtechnology, dimensions scale are below 1 + c mm, where varies based on process type. “classic” processes usually cannot be simply scaled down, and tools require thorough structural changes. Microforming has been isolated from area forming governed by modified laws. proposed new technological ultrasonic orbital microforming (UOM) its related phenomena possible only a microscale. UOM...

Rapid development of micro-machines, which partly needs metallic micro-parts, is nowadays a fact.A very promising way micro-parts manufacturing micro-blanking.For quite complicated 2D shapes, like micro-gears, dies might be rather easy manufactured by wire-cutting.Production micro-punches seems to much more difficult.In this article solution consisting two components: punch body based on standard and mechanically joined end -bimetallic micro-punch -is proposed.Joining process the extrusion,...

In recent years, there has been a clear change towards the replacement of devices using different types energy with electrical devices. These devices, for most part, have simpler construction than other which predisposes them to miniaturization. An important element is micro-contacts successfully riveted by means planetary riveting. Recently, monolithic contacts are replaced bimetallic contacts. their case, use processes leads delamination materials at various stages riveting or...