Analysis of experimental results of the inlet for the NASA hypersonic research engine aerothermodynamic integration model

An aerodynamic engine inlet analysis was performed on the experimental results obtained at nominal Mach numbers of 5, 6, and 7 from the NASA Hypersonic Research Engine (HRE) Aerothermodynamic Integration Model (AIM). Incorporation on the AIM of the mixed-compression inlet design represented the final phase of an inlet development program of the HRE Project. The purpose of this analysis was to compare the AIM inlet experimental results with theoretical results. Experimental performance was based on measured surface pressures used in a one-dimensional force-momentum theorem. Results of the analysis indicate that surface static-pressure measurements agree reasonably well with theoretical predictions except in the regions where the theory predicts large pressure discontinuities. Experimental and theoretical results both based on the one-dimensional force-momentum theorem yielded inlet performance parameters as functions of Mach number that exhibited reasonable agreement. Previous predictions of inlet unstart that resulted from pressure disturbances created by fuel injection and combustion appeared to be pessimistic

The Effect of Inkjet Ink Composition on Rheology And Jetting Behaviour

This work presents recent results on the way linear and non linear viscoelastic properties of the fluids affect the jetting mechanism. Recent progress on quantitative characterising both high frequency linear (LVE) and non-linear (NLVE) viscoelasticity of fluids allows fluids to be assessed for their jettability before using such materials in a DoD print head. In term of linear viscoelastic measurements, the Piezo Axial Vibrator (PAV) was used to probe the rheology of the fluids on a frequency range between 10Hz and 10000Hz. A filament stretching apparatus, called the “Cambridge Trimaster”, was used in combination with high speed cinematography, to characterize the fluids high speed stretching and break-up behaviour. The series of fluids investigated here consist in dilutions of mono disperse polystyrene with different molecular weight (110, 210, 306 and 488 kg/mol respectively) diluted in diethyl phthalate. The choice of polymer weights and concentrations were chosen to match both the complex viscosity and the LVE. However, non linear rheological data experiments exhibit differences in the fluid relaxation time and filament break-up mechanism. Ultra-high speed cinematography of DoD jetting events were correlated with filament break-up experiments and demonstrated that fluid rheology provides valuable information on the jetting quality of the fluids

An inlet analysis for the NASA hypersonic research engine aerothermodynamic integration model

A theoretical analysis for the inlet of the NASA Hypersonic Research Engine (HRE) Aerothermodynamic Integration Model (AIM) has been undertaken by use of a method-of-characteristics computer program. The purpose of the analysis was to obtain pretest information on the full-scale HRE inlet in support of the experimental AIM program (completed May 1974). Mass-flow-ratio and additive-drag-coefficient schedules were obtained that well defined the range effected in the AIM tests. Mass-weighted average inlet total-pressure recovery, kinetic energy efficiency, and throat Mach numbers were obtained

An integrated aerospace requirement setting and risk analysis tool for life cycle cost reduction and system design improvement

In the early conceptual stage of the service orientated model, decisions regarding the design of a new technical product are largely influenced by Service Requirements. Those decisions, therefore, have to merge both technical and business aspects to obtain desired product reliability and reduced Whole Life Cost (WLC). It is, therefore, critical at that phase to define the risk of potential noncompliance of Service Requirements in order to ensure the right design choices; as these decisions have a large impact on the overall product and service development. This paper presents outcome of research project to investigate different approaches used by companies to analyse Service Requirements to achieve reduced Life Cycle Cost (LCC). Analysis using Weibull distribution and Monte Carlo principle have been proposed here; based on the conducted literature review these are considered as the most widely used techniques in product reliability studies. Based on those techniques, a methodology and its software tool for risk evaluation of failure to deliver a new product against Service Requirements are presented in this paper. This is part of the on-going research project which, apart from analysing the gap between the current Service Requirements achievements and the design targets for a new aircraft engine, it also facilitates an optimisation of those requirements at the minimum risk of nonconformity

Enhancing service requirements of technical product-service systems

Due to the integration of product and services as a new business model, product reliability and strategies for cost reduction at the early design stage have become important factors for many manufacturing firms. It is, therefore, critical at this phase to analyse the risk involved with Service Requirements noncompliance in order to help designers make informed decisions; as these decisions have a large impact on the Product Life Cycle (PLC). An investigation has been performed into how Service Requirements are analysed in a service orientated business to achieve reduced Life Cycle Cost (LCC) and improvements of existing Service Requirements. Weibull distribution and Monte Carlo principle have been proposed to do so; as they are considered as the most widely used in product reliability studies in the industry sector. A generic methodology for risk evaluation of failure to deliver a new product against Service Requirements is presented in this paper. This is part of the ongoing research project which aims to, apart from comparing current and targeted Service Requirements, it also facilitates an optimisation of them at the minimum risk of nonconformity

Hypersonic research engine/aerothermodynamic integration model, experimental results. Volume 2: Mach 6 performance

Computer program performance results of a Mach 6 hypersonic research engine during supersonic and subsonic combustion modes were presented. The combustion mode transition was successfully performed, exit surveys made, and effects of altitude, angle of attack, and inlet spike position were determined during these tests

NASA's Hypersonic Research Engine Project: A review

The goals of the NASA Hypersonic Research Engine (HRE) Project, which began in 1964, were to design, develop, and construct a high-performance hypersonic research ramjet/scramjet engine for flight tests of the developed concept over the speed range of Mach 4 to 8. The project was planned to be accomplished in three phases: project definition, research engine development, and flight test using the X-15A-2 research airplane, which was modified to carry hydrogen fuel for the research engine. The project goal of an engine flight test was eliminated when the X-15 program was canceled in 1968. Ground tests of full-scale engine models then became the focus of the project. Two axisymmetric full-scale engine models, having 18-inch-diameter cowls, were fabricated and tested: a structural model and combustion/propulsion model. A brief historical review of the project, with salient features, typical data results, and lessons learned, is presented. An extensive number of documents were generated during the HRE Project and are listed

Residence times and mixing of a novel continuous oscillatory flow meso reactor

A novel meso reactor based on oscillatory flow technology (Harvey et al., 2001) has been recently presented in Harvey et al. (2003) as a new technology for reaction engineering and particle suspension applications. Due to the demonstrated enhanced performances for fluid micro mixing and suspension of catalyst beads and to the small volume of the reactor, this novel miniature reactor is suitable for applications at specialist chemical manufacture and high throughput screening. Furthermore, a high control of environment conditions (e.g. mixing intensity, temperature) coupled with an online monitoring turns this reactor suitable for smallscale applications to the bioengineering field, such as for fast parallel bioprocessing tasks. This work concerns with the fluid dynamics characterisation of a novel miniature reactor. Experimental results using state-of-art fibre-optic technology is used in order to demonstrate that an accurate control of the residence time distribution (RTD) of liquid and solid phases can be achieved within this reactor as well as enhanced (oxygen) mass transfer rates. Furthermore, numerical simulations using Fluent ® software will be presented where simulated RTDs agrees with the experimental results. The meso reactor unit consists of 4.4 mm internal diameter and 35 cm long jacketed glass tubes, with a unit volume of 4.5 ml and provided with smooth periodic constrictions (SPCs), with an average baffle spacing of 13 mm. The internal diameter at the constricted zone (baffle internal diameter) is 1.6 mm, leading to a reduction of the baffle free are of 87 %. This unit is able to support batch or continuous operations mode, simply by configuring the tubes in parallel or in series, according to the intended application. Mixing is achieved by oscillating the fluid at the bottom or the top of the reactor by means of a piston pump, using oscillation amplitudes and frequencies ranging from 0 to 4 mm centre-to-peak and 0 to 25 Hz, respectively. Experimental studies using the Particle Image Velocimetry (PIV) technique (Harvey et al., 2003) showed that different fluid mechanics are originated at different oscillation conditions (oscillation amplitudes and frequencies). A plug flow or a stirred tank behaviour can be obtained just by controlling the oscillation conditions. At low oscillatory Reynolds numbers (Reo), e.g. 10 to 100, the formation of axisymmetric eddies detached from the constrictions is coupled with low axial velocities and makes it possible to continuously operate the reactor in a plug flow mode. Increasing the Reo to values higher than 100, the eddy symmetry is broken and a complete mixing state is achieved inside the meso reactor. Low oscillation amplitudes must be used if axial dispersion is intended to be minimized, namely at plug flow setup. Through an overall oscillation cycle, changes of the location of the main flow stream from near the wall to the centre of each cavity and vice-versa was observed and is expected to lead to high mass and heat transfer rates (Perry, 2002). Due to the observed high radial velocities, narrow residence times distributions are expected to be obtained (Perry, 2002). Also high axial circulation rates were also observed at high Reos (above 100) and it was proved to lead to an enhanced performance on catalyst beads suspension. The relation of this fluid mechanics with the real performance of this novel meso reactor will be demonstrated. Tracer injection technique is applied to perform RTD studies inside a single SPC tube of the meso reactor. Spectroscopy UV/VIS technique is used to measure the concentration of a coloured tracer at the inlet and outlet (at continuous mode) or at the bottom and the top of the tube (at batch mode). A fibre optic apparatus is employed in order to obtain highly accurate online measurements of the UV/VIS absorbance. Mixing times are calculated for experiments at batch mode. Different flow rates are used to determine the effect of the flow rate over the RTD at continuous operation and axial dispersion is presented by the Bodenstein number, Bo. Determination of KL.a values is achieved by online measurement of the oxygen concentration using a special fibre optic probe. The working tip of the probe was dip-coated with a ruthenium complex immobilised in a sol-gel matrix. This complex is excited to fluorescence by a blue led (470 nm outpuk peak) and the level of the fluorescence is inversely related to the concentration of the oxygen through the Stern-Volmer equation (Wang et al., 1999), which is measured by the fibre-optic apparatus. Retention of solid phases (e.g. catalyst beads and yeast cells) inside the meso reactor will also be tested. Further studies using the Computation Fluid Dynamics (CFD) technique will be presented where accurate prediction of the distribution of residence times is achieved. The use of the distributionfunctions permits to classify the flow behaviour inside this novel meso reactor patterns and to calculate mixing efficiencies and axial dispersion coefficients (expressed by the Bo number) at different oscillation conditions. A simple 2-D axisymmetric laminar model showed good agreement with flow patterns visualisations using PIV for Reo below 100 but a 3-D model with a very fine mesh was required to simulate breakage of axisymmetry. Consequently, 3-D models based on laminar and Large Eddy Simulations (LES) will be used to maximize the matching of RTD at higher oscillation conditions. Main intended application of CFDs to this novel meso reactor is the design of a meso reactor unit, which could operate at the best oscillation conditions and flow rate for cell cultures and biocatalyst applications