Chamber pressure

About: Chamber pressure is a research topic. Over the lifetime, 2988 publications have been published within this topic receiving 30725 citations.

Mixing Characteristics of Underexpanded Elliptic Sonic Jets from Orifice and Nozzle

Abstract: The mixing characteristics of elliptical sonic jets issuing from an orifice and a convergent nozzle with an identical elliptical exit of aspect ratio of two were studied experimentally in the presence of favorable pressure gradients corresponding to nozzle pressure ratios of two to five, in steps of one. To quantify the aerodynamic mixing of the free jets with the fluid entrained from the surrounding environment, the jet centerline pitot pressure distribution and radial pitot pressure profiles along the major and minor axes directions of the jet were measured. The centerline pitot pressure variation of the orifice and nozzle jets shows that the decay of the jet from the nozzle is faster than the jet from the orifice at nozzle pressure ratios more than two. But at a nozzle pressure ratio of two, the decay of both the jets are close to each other. The pressure profiles demonstrate that the axis-switching location shifts upstream with an increase of nozzle pressure ratio for both the jets, implying that the ...

Large Eddy Simulation of Combustion and Heat Transfer in a Single Element GCH4/GOx Rocket Combustor

Abstract: The single element GCH4/GOx rocket combustion chamber developed at the Technische Universitat Munchen has been computed using Large Eddy Simulation. The aim of this work is to analyze the flow and combustion features at high pressure, with a particular focus on the prediction of wall heat flux, a key point for the development of reusable engines. The impact of the flow and flame, as well as of the model used, on thermal loads is investigated. Longitudinal distribution of wall heat flux, as well as chamber pressure, have been plotted against experimental data, showing a good agreement. The link between the heat released by the flame, the heat losses and the chamber pressure has been explained by performing an energetic balance of the combustion chamber. A thermally chained numerical simulation of the combustor structure has been used to validate the hypothesis used in the LES.

Effect of deposition pressure on the properties of magnetron-sputter-deposited molybdenum back contacts for CIGS solar cells

Abstract: Molybdenum (Mo) thin films were deposited onto soda-lime glass substrates by DC magnetron sputtering of a Mo target at various chamber pressures ranging from 1.5 × 10−3 to 7.5 × 10−3 mbar. The film properties were analysed with regards to their application as back electrode in copper indium gallium diselenide (CIGS) solar cells. It is observed that the resulting film morphology and microstructure were strongly affected by deposition pressure. Mo films deposited at a low pressure possess a high density and a low sheet resistance. These films also have a compact microstructure and a compressive strain, which lead to poor adhesion. The adhesion can be improved by increasing the chamber pressure, which has negative effects on the sheet resistance, optical reflection and porosity of the films. On the basis of these results, a method has been established to fabricate low-resistivity Mo films on soda-lime glass with very good adhesion for CIGS solar cell applications.

Gap Adjustable Molten Metal DoD Inkjet System With Cone-Shaped Piston Head

Abstract: In this paper, we present the design, fabrication, and performance test of a gap adjustable molten metal drop-on-demand (DoD) inkjet system with a cone-shaped piston head, which can eject a droplet of lead-free molten solder at high temperature. The gap adjustable mechanism with the cone-shaped piston head is proposed for optimizing the gap distance between the chamber wall and piston head. The droplet diameter and velocity can be controlled in a wide range by moving the initial gap distance and minutely by controlling the chamber pressure. Stability and satellite can be partly adjusted by controlling the initial gap distance and the chamber pressure, respectively. The working temperature is improved by locating the piezoelectric actuator at the outside of the furnace and by inserting the insulation block between the print head and the actuator. From a practical point of view, the molten metal DoD inkjet system presents a simple structure for easily interchangeable nozzle parts, even though the nozzle is choked. The gap adjustable molten metal DoD inkjet system with cone-shaped piston head has great potential as a manufacturing tool for direct printing a viscous material at various temperatures. It is expected to be applicable in many industrial fields including semiconductor packaging, electrode bonding, printed electronics, information, and display industry.