Heat conduction controlled combustion for scramjet applications

The use of heat conduction flame generated in a premixed supersonic stream is discussed. It is shown that the flame is controlled initially by heat conduction and then by chemical reaction. Such a flame is shorter than the diffusion type of flame and therefore it requires a much shorter burner. The mixing is obtained by injecting the hydrogen in the inlet. Then the inlet can be cooled by film cooling

Experimental investigation of wall shock cancellation and reduction of wall interference in transonic testing

A series of experiments were performed to evaluate the effectiveness of a three-dimensional land and groove wall geometry and a variable permeability distribution to reduce the interference produced by the porous walls of a supercritical transonic test section. The three-dimensional wall geometry was found to diffuse the pressure perturbations caused by small local mismatches in wall porosity permitting the use of a relatively coarse wall porosity control to reduce or eliminate wall interference effects. The wall porosity distribution required was found to be a sensitive function of Mach number requiring that the Mach number repeatability characteristics of the test apparatus be quite good. The effectiveness of a variable porosity wall is greatest in the upstream region of the test section where the pressure differences across the wall are largest. An effective variable porosity wall in the down stream region of the test section requires the use of a slightly convergent test section geometry

Effect of premixing quality on oxides of nitrogen in gas turbine combustors foi HC

Experiments were conducted to determine the effectiveness of several premixing prevaporizing gas turbine combustor designs in reducing formation of oxides of nitrogen at the supersonic cruise condition. An atomized spray from a single injector mounted on the axis of the mixer tube produced a high initial concentration of fuel near the axis and only moderate premixed conditions entering the combustor. A fuel spray produced by 12 flush-mounted normal injection orifices in the mixer tube wall produced a good initial despersion of fuel and resulted in nearly complete premixing. Oxides of nitrogen emission levels of the order of 0.2 g NO2/kg fuel were obtained at 99 percent combustion efficiency at an equivalence ratio of 0.4. Overall total pressure drop was less than 3 percent through the 1-meter combustor module

Prevaporization and premixing to obtain low oxides of nitrogen in gas turbine combustors

Tests were conducted to determine the effectiveness of prevaporization and premixing in reducing the formation of oxides of nitrogen in a gas turbine type combustor using liquid JP-5 fuel at the supersonic cruise condition. The combustor inlet temperature was 833 K (1500 R) at a pressure of 4 atmospheres and a reference velocity of 46 m/sec (150 ft/sec). An order of magnitude reduction in nitric oxide emissions was achieved. Nitric oxide emission indices as low as 0.6 gm NO2/kg fuel were measured at an equivalence ratio of 0.29 with one percent combustion inefficiency without vitiation of the mixer stream

Analysis and design of three dimensional supersonic nozzles. Volume 4: Similarity laws for nozzle flows

The development of nozzles for hypersonic aircraft is discussed. The simulation of actual nozzle flows with low temperature nonreactive gases is described. Mathematical models of the flow equations nd thermodynamic relations are developed. Cold flow simulation tests were conducted and the results are included

Expectations for a new calorimetric neutrino mass experiment

A large calorimetric neutrino mass experiment using thermal detectors is expected to play a crucial role in the challenge for directly assessing the neutrino mass. We discuss and compare here two approaches to the estimation of the experimental sensitivity of such an experiment. The first method uses an analytic formulation and allows to readily obtain a sensible estimate over a wide range of experimental configurations. The second method is based on a frequentist Montecarlo technique and is more precise and reliable. The Montecarlo approach is then exploited to study the main sources of systematic uncertainties peculiar to calorimetric experiments. Finally, the tools are applied to investigate the optimal experimental configuration for a calorimetric experiment with Rhenium based thermal detectors.Comment: 25 pagers, 16 figure

Statistical Mechanics of Phase-Space Curves

We study the classical statistical mechanics of a phase-space curve. This unveils a mechanism that, via the associated entropic force, provides us with a simple realization of effects such as confinement, hard core, and asymptotic freedom. Additionally, we obtain negative specific heats, a distinctive feature of self-gravitating systems and negative pressures, typical of dark energy.Comment: 24 pages, 15 figure

Open Innovation, ambiguity and technological convergence

Objectives. Current paper aims to provide a fresh conceptual framework on the relationship among open innovation, decision ambiguity, and technological convergence. We argue that there is a curvilinear relationship between open innovation and both technological convergence and ambiguity. Contained level of convergence and ambiguity foster open innovation, whilst an excess of them is an impediment to collaboration. Technological convergence further acts as a moderator for ambiguity, in light of the benefits of isomorphism. Methodology. We propose a conceptual framework for open innovation decisions after accurately reviewing the main literature antecedents. Findings. We suggest an inverse u-shaped relationship between open innovation and either ambiguity or technological convergence. Research limits. In future, the theoretical framework proposed by thus study has to be tested with robust and proper statistical techniques on large scale samples. Practical implications. The model offers a heuristic for open innovation decisions under ambiguity. Originality of the study. To the best of our knowledge, the relationship linking open innovation, technological convergence and ambiguity emerges as a literature gap. This study tackles this issue, proposing an interpretation for the analysis of alliances decision in innovation