Very Low Thrust Gaseous Oxygen-hydrogen Rocket Engine Ignition Technology

An experimental program was performed to determine the minimum energy per spark for reliable and repeatable ignition of gaseous oxygen (GO2) and gaseous hydrogen (GH2) in very low thrust 0.44 to 2.22-N (0.10 to 0.50-lb sub f) rocket engines or spacecraft and satellite attitude control systems (ACS) application. Initially, the testing was conducted at ambient conditions, with the results subsequently verified under vacuum conditions. An experimental breadboard electrical exciter that delivered 0.2 to 0.3 mj per spark was developed and demonstrated by repeated ignitions of a 2.22-N (0.50-lb sub f) thruster in a vacuum chamber with test durations up to 30 min

Detonation-flame arrester devices for gasoline cargo vapor recovery systems

Empirical data on the deflagration-to-detonation run-up distance for flowing mixtures of gasoline and air in 15.2-cm- (6.0-in.-) diameter piping simulating a vapor recovery system are presented. The quenching capability of eight selected flame control devices subjected to repeated stable detonations was evaluated. The successful detonation-flame arresters were: (1) spiral-wound, crimped aluminum ribbon, (2) foamed nickel-chrome metal, (3) vertically packed bed of aluminum Ballast rings, and (4) water-trap or hydraulic back-pressure valve. Installation configurations for two of the more applicable arresters, the spiral-wound, crimped stainless-steel ribbon and the vertically packed bed of aluminum Ballast rings, were further optimized by a series of parametric tests. The final configuration of these two arresters was demonstrated with repeated detonation tests at conditions that simulated vapor recovery system operation. On these tests, the combustible mixture of gasoline and air continued to flow through the piping for periods up to 120 seconds after the initial detonation had been arrested. There was no indication of continuous burning or reignition occurring on either side of the test arresters

Flashback flame arrester devices for fuel cargo tank vapor vents

The flame quenching capability of four types of flame arresting devices suitable for installation on fuel cargo tank vents of marine transport vessels is evaluated. A single 30 mesh screen, a dual 20 mesh screen, a spiral wound crimped metal ribbon, and a packed bed of ballast rings were tested. Flame speed and flame penetration of the test arresters were determined. Eight fuels representative of bulk cargoes were tested. The test arresters quenched a minimum of three flashback flames from all eight fuels, with one exception: high speed ethylene flames penetrated the dual 20 mesh screen on three tests. The arresters withstood the sustained flame from a propane/air mixture for 30 minutes. None of the arresters withstood the sustained flame from an ethylene/air mixture for more than 7 minutes

Test program to demonstrate the stability of hydrazine in propellant tanks

A 24-month coupon test program to evaluate the decomposition of propellant tanks is reported. The propellant fuel evaluated was monopropellant-grade hydrazine (N2H4), which is normally a colorless, fuming, corrosive, strongly reducing liquid. The degree of hydrazine decomposition was determined by means of chemical analyses of the liquid and evolved gases at the end of the test program. The experimental rates of hydrazine decomposition were determined to be within acceptable limits. The propellant tank materials and material combinations were not degraded by a 2-year exposure to hydrazine propellant. This was verified using change-of-weight determinations and microscopic examination of the specimen surface before and after exposure, and by posttest chemical analyses of hydrazine liquid for residual metal content

Perceived Managerial Functions in the Front-End of Innovation

Purpose: Exploring managerial functions and related activities of inexperienced projectmanagers in the front-end of the innovation process (FEI). Design/methodology/approach: Fifteen student project managers were interviewed while they were engaged in the front-end phase of their respective 8-month projects. 757 interview transcript segments on their perceptions of managerial functions were categorized based on thematic similarity of content.Findings: Four major managerial functions emerged: providing structural support, coordinating and acting as a link, empowering the team, and encouraging and providing social support. Out of these, traditional task-oriented managerial functions were emphasized. Research limitations/implications: Although limited by the small amount of participants in a university setting, the results suggest that task-oriented managerial functions are dominant even in the FEI for inexperienced project managers. More research is needed to understand the antecedents and consequences of such task- dominance, and whether it persists as more experience is accrued. On the other hand, domain knowledge seemed to play a smaller role than indicated by previous research. Practical implications: Project managers should pay attention to creating structure in the uncertain front-end phase. Swift familiarization with the capabilities and practices of each team member cannot be overemphasized, as otherwise the heterogeneity of the team might become a limitation rather than asset. On the other hand, domain experience of the manager may not be necessary in the FEI. Originality/value: The study addresses the gap in previous research on managerial functions specifically in the FEI. Task-oriented managerial functions emerged as way of novice project managers attempting to deal with the fluctuating contingencies in order to foster innovation.Peer reviewe

Handbook of recommended practices for the determination of liquid monopropellant rocket engine performance

The design, installation, and operation of systems to be used for directly measuring quantities of fundamental importance to the determination of monopropellant thruster performance is described. Areas covered include: (1) force and impulse measurement; (2) propellant mass usage and flow measurement; (3) pressure measurement; (4) temperature measurement; (5) exhaust gas composition measurement; and (6) data reduction and performance determination

Handbook for estimating toxic fuel hazards

Computer program predicts, from readily available meteorological data, concentration and dosage fields downwind from ground-level and elevated sources of toxic fuel emissions. Mathematical model is applicable to hot plume rise from industrial stacks and should also be of interest to air pollution meteorologists

An Exact Algorithm for TSP in Degree-3 Graphs via Circuit Procedure and Amortization on Connectivity Structure

The paper presents an O^*(1.2312^n)-time and polynomial-space algorithm for the traveling salesman problem in an n-vertex graph with maximum degree 3. This improves the previous time bounds of O^*(1.251^n) by Iwama and Nakashima and O^*(1.260^n) by Eppstein. Our algorithm is a simple branch-and-search algorithm. The only branch rule is designed on a cut-circuit structure of a graph induced by unprocessed edges. To improve a time bound by a simple analysis on measure and conquer, we introduce an amortization scheme over the cut-circuit structure by defining the measure of an instance to be the sum of not only weights of vertices but also weights of connected components of the induced graph.Comment: 24 pages and 4 figure

Doppler-Free Spectroscopy of Weak Transitions: An Analytical Model Applied to Formaldehyde

Experimental observation of Doppler-free signals for weak transitions can be greatly facilitated by an estimate for their expected amplitudes. We derive an analytical model which allows the Doppler-free amplitude to be estimated for small Doppler-free signals. Application of this model to formaldehyde allows the amplitude of experimentally observed Doppler-free signals to be reproduced to within the experimental error.Comment: 7 pages, 7 figures, 1 table, v2: many small improvements + corrected line assignmen