Heat-barrier coatings for combustion chambers

Arc-plasma-sprayed layered coating of graded Inconel and zirconia protects film-coolant ring below injector plate of rocket engine combustion chamber. Interfacial temperature is designed for minimum buildup of stress and to avoid melting of the metal phase in the graded layers

Granular two-phase insulation systems

Easily prepared system, consisting of matrix of hollow zirconia microspheres containing dispersed tungsten powder, produces minimum-cost, prototype test specimen. Combination represents basic concept of highly reflective dispersed phase in low density insulative matrix and is stable at 2200 K. Other combinations of materials are suggested

Intergranular metal phase increases thermal shock resistance of ceramic coating

Dispersed copper phase increases the thermal shock resistance of a plasma-arc-sprayed coating of zirconia used as a heat barrier on a metal substrate. A small amount of copper is deposited on the granules of the zirconia powder before arc-spraying the resultant powder composite onto the substrate

Ceramics for advanced O2/H2 application

Ceramics are prime candidate materials for advanced rocket engines because they possess high-temperature capability, a tolerance for aggressive environments, and low density. A program was conducted to assess the applicability of structural ceramics to advanced versions of the Space Shuttle main engine (SSME). Operating conditions of ceramic turbine components were defined and each component in the hot-gas path was assessed in regard to materials selection, manufacturing process and feasibility, and relative structural reliability. The conclusion is that ceramic components would be viable in advanced SSME turbopumps

Global behaviour corresponding to the absolute instability of the rotating-disc boundary layer

A study is carried out of the linear global behaviour corresponding to the absolute instability of the rotating-disc boundary layer. It is based on direct numerical simulations of the complete linearized Navier–Stokes equations obtained with the novel velocity–vorticity method described in Davies & Carpenter (2001). As the equations are linear, they become separable with respect to the azimuthal coordinate, $\theta$. This permits us to simulate a single azimuthal mode. Impulse-like excitation is used throughout. This creates disturbances that take the form of wavepackets, initially containing a wide range of frequencies. When the real spatially inhomogeneous flow is approximated by a spatially homogeneous flow (the so-called parallel-flow approximation) the results ofthe simulations are fully in accordance with the theory of Lingwood (1995). If the flow parameters are such that her theory indicates convective behaviour the simulations clearly exhibit the same behaviour. And behaviour fully consistent with absolute instability is always found when the flow parameters lie within the theoretical absolutely unstable region. The numerical simulations of the actual inhomogeneous flow reproduce the behaviour seen in the experimental study of Lingwood (1996). In particular, there is close agreement between simulation and experiment for the ray paths traced out by the leading and trailing edges of the wavepackets. In absolutely unstable regions the short-term behaviour of the simulated disturbances exhibits strong temporal growth and upstream propagation. This is not sustained for longer times, however. The study suggests that convective behaviour eventually dominates at all the Reynolds numbers investigated, even for strongly absolutely unstable regions. Thus the absolute instability of the rotating-disc boundary layer does not produce a linear amplified global mode as observed in many other flows. Instead the absolute instability seems to be associated with transient temporal growth, much like an algebraically growing disturbance. There is no evidence of the absolute instability giving rise to a global oscillator. The maximum growth rates found for the simulated disturbances in the spatially inhomogeneous flow are determined by the convective components and are little different in the absolutely unstable cases from the purely convectively unstable ones. In addition to the study of the global behaviour for the usual rigid-walled rotating disc, we also investigated the effect of replacing an annular region of the disc surface with a compliant wall. It was found that the compliant annulus had the effect of suppressing the transient temporal growth in the inboard (i.e. upstream) absolutely unstable region. As time progressed the upstream influence of the compliant region became more extensive

Survey and Evaluation of Supersonic Base Flow Theories

Survey and evaluation of supersonic base flow theorie

The initial development of the general non-isoenergetic compressible free shear layer

Numerical solution of partial differential equations governing intial development of general nonisoenergetic compressible free shear laye

Good Teaching and Learning in the Academy

This paper is based on original research at five Queensland Universities. It compared the teaching strategies of law, education and science academics in an attempt to discover any relationship between teaching strategies and subject matter. It also examined the teaching policy at each university, specifically university definitions of good teaching and its relationship to use of technology. The purpose of this research was to determine whether or not specific understandings of good teaching in the academy prevailed, and whether or not this (dis)advantaged certain faculties. From an initial case study of QUT, the basic findings from our research were as follows: • good teaching was found to have two central features: it was student centred and technologically innovative, • irrespective of discipline, all lecturers espoused the importance of student centred learning as integral to good teaching, even though, in practice, teaching style appeared to be largely determined by subject matter, • the most innovative and technological units were the least student centred We conclude that what counts as good teaching is both contested and context bound. This has major implications for monolithic definitions of good teaching as espoused by university policy and teaching units. It also has clear ramifications for university measures of effective and innovative teaching and thus standardised procedures for both academic promotion and teaching practices across the university

Technology meets Student Centred Learning: "good practice" in university teaching

In tertiary institutions across Australia, good teaching increasingly means student centred and technological. In this paper, this is demonstrated by a case study of Queensland University of Technology, where recent policy on teaching, promoted by management and supported by teaching and learning services, suggests two things. The first that it is impossible for QUT academics to educate their students without using inclusive and dialogical methods of instruction. The second, that at QUT, effective use of technology is paramount to the success of such student centred learning. This relationship, given legitimacy through the QUT focus on flexible delivery, raises larger questions about the dominant assumptions regarding ‘good practice’ within the university setting. In this context, the dominant assumption is the superiority of progressive education and this in itself assumes further a humanistic notion of the self. This paper will suggest three things. First that such assumptions should be challenged within tertiary teaching theory and practice, as they have been within the wider domain of social and cultural theory. Second that the new valorised practices of progressive education actually depend upon old derogated practices, but that this reliance is either downplayed or disregarded. Third, that the resulting unified policy on good teaching, needs rethinking

A flight-rated liquid-cooled garment for use within a full-pressure suit

A flight rated liquid cooled garment system for use inside a full pressure suit has been designed, fabricated, and tested. High temperature tests with this system have indicated that heat is absorbed at a rate decreasing from 224 kg-cal/hr to 143 kg-cal/hr over a 40-min period. The first 30 min are very comfortable; thereafter a gradual heat load builds that results in mild sweating at the end of the 40-min period. In flight tests during hot weather when this cooling system was worn under a regulation flight suit, the pilot reported that temperatures were comfortable and that the garment prevented sweating