Experimental Results for an Annular Aerospike with Differential Throttling

A) MSFC funded an internal study on Altitude Compensating Nozzles: 1) Develop an ACN design and performance prediction tool. 2) Design, build and test cold flow ACN nozzles. 3) An annular aerospike nozzle was designed and tested. 4) Incorporated differential throttling to assess Thrust Vector Control. B) Objective of the test hardware: 1) Provide design tool verification. 2) Provide benchmark data for CFD calculations. 3) Experimentally measure side force, or TVC, for a differentially throttled annular aerospike

Details of Side Load Test Data and Analysis for a Truncated Ideal Contour Nozzle and a Parabolic Contour Nozzle

Two cold flow subscale nozzles were tested for side load characteristics during simulated nozzle start transients. The two test article contours were a truncated ideal and a parabolic. The current paper is an extension of a 2009 AIAA JPC paper on the test results for the same two nozzle test articles. The side load moments were measured with the strain tube approach in MSFC s Nozzle Test Facility. The processing techniques implemented to convert the strain gage signals into side load moment data are explained. Nozzle wall pressure profiles for separated nozzle flow at many NPRs are presented and discussed in detail. The effect of the test cell diffuser inlet on the parabolic nozzle s wall pressure profiles for separated flow is shown. The maximum measured side load moments for the two contours are compared. The truncated ideal contour s peak side load moment was 45% of that of the parabolic contour. The calculated side load moments, via mean-plus-three-standard-deviations at each nozzle pressure ratio, reproduced the characteristics and absolute values of measured maximums for both contours. The effect of facility vibration on the measured side load moments is quantified and the effect on uncertainty is calculated. The nozzle contour designs are discussed and the impact of a minor fabrication flaw in the nozzle contours is explained

Cold Flow Plume Entrainment Test Final Report NTF Test Number 2456

As part of the Space Shuttle Return to Flight (RTF) program, Marshall Space Flight Center (MSFC) performed computational fluid dynamics (CFD) analysis to define the velocity flowfields around the Shuttle stack at liftoff. These CFD predicted velocity flowfields were used in debris transport analysis (DTA). High speed flows such as plumes induce or 'entrain' mass from the surrounding environment. Previous work had shown that CFD analysis over-predicts plume induced flows. Therefore, the DTA would tend to 1) predict more debris impacts, and 2) the debris velocity (and kinetic energy) of those impacts would be too high. At a November, 2004 peer-review it was recommended that the Liftoff DTA team quantify the uncertainty in the DTA caused by the CFD's over prediction of plume induced flow. To do so, the Liftoff DTA team needed benchmark quality data for plume induced flow to quantify the CFD accuracy and its effect on the DTA. MSFC's Nozzle Test Facility (NTF) conducted the "Nozzle Induced Flows test, P#2456" to obtain experimental data for plume induced flows for nozzle flow exhausting into q quiescent freestream. Planning for the test began in December, 2004 and the experimental data was obtained in February and March of 2005. The funding for this test was provided by MSFC's Space Shuttle Propulsion Systems Integration and Engineering office

Wall Pressure Unsteadiness and Side Loads in Overexpanded Rocket Nozzles

Surveys of both the static and dynamic wall pressure signatures on the interior surface of a sub-scale, cold-flow and thrust optimized parabolic nozzle are conducted during fixed nozzle pressure ratios corresponding to FSS and RSS states. The motive is to develop a better understanding for the sources of off-axis loads during the transient start-up of overexpanded rocket nozzles. During FSS state, pressure spectra reveal frequency content resembling SWTBLI. Presumably, when the internal flow is in RSS state, separation bubbles are trapped by shocks and expansion waves; interactions between the separated flow regions and the waves produce asymmetric pressure distributions. An analysis of the azimuthal modes reveals how the breathing mode encompasses most of the resolved energy and that the side load inducing mode is coherent with the response moment measured by strain gauges mounted upstream of the nozzle on a flexible tube. Finally, the unsteady pressure is locally more energetic during RSS, albeit direct measurements of the response moments indicate higher side load activity when in FSS state. It is postulated that these discrepancies are attributed to cancellation effects between annular separation bubbles

Critical review of existing built environment resilience frameworks: Directions for future research

Resilience, in general, is widely considered as a system's capacity to proactively adapt to external disturbances and recover from them. However, the existing resilience framework research is still quite fragmented and the links behind various studies are not straightforwardly accessible. The paper provides a critical state-of-the-art review of both quantitative and qualitative considerations of resilience, approached from a built environment engineering perspective, with a focus on geo-environmental hazards. A research gap is identified and translated into a holistic and systemic approach to conceptualise resilience, factoring in related concepts such as vulnerability, adaptive capacity and recoverability. A generic built environment resilience framework is proposed informed by a critical and comprehensive review of the related literature. The paper concludes with insights into four key strategic areas requiring further research, namely: (a) risk based cost optimal resilient design and standards of buildings and infrastructures, (b) model based evaluation and optimisation of buildings and infrastructures, (c) integrated risk modelling, inference and forecasting, and (d) heterogeneous disaster data acquisition, integration, security and management

Experimental Results for an Annular Aerospike with Differential Throttling

Marshall Space Flight Center funded an internal study on Altitude Compensating Nozzles (ACN) for aerospike engines. The experimental hardware for the engine test is described in this viewgraph presentation, as well as the results of the experiment. The results include spike wall pressures, nozzle efficiency, and side force for four nozzle configurations

Intratesticular arteriovenous malformation: A rare benign testicular lesion in an adolescent male

We present the clinical course and imaging findings of an intratesticular arteriovenous malformation found in an adolescent patient.The patient presented for evaluation of a possible testicular mass. Evaluation included grayscale and Doppler ultrasound that demonstrated a vascular mass. Serum tumor markers were unremarkable. Magnetic resonance imaging was used to make the diagnosis of intratesticular arteriovenous malformation.Intratesticular arteriovenous malformations are exceedingly rare, with only four other cases noted on literature review. This case presents unique findings including testicular microlithiasis and a history of cryptorchidism. The case was managed conservatively with ultrasound surveillance at six months

Feasibility of Developing a Refrigerant-Based Propulsion System for Small Spacecraft

This paper documents the feasibility of developing a low pressure, low-budget, two-phase refrigerant propulsion system for small spacecraft. The spacecraft design teams at the University of Missouri-Rolla, University of Texas at Austin, and Washington University in St Louis have collaboratively researched and assessed the feasibility of using a refrigerant propellant to provide a safe and practical type of propulsion system for the small spacecraft community. As an alternative to a typical inert cold-gas system, the teams investigated two-phase refrigerant-based systems motivated by the excellent propellant storage advantages and the ease of use and inherent safety. A primary benefit is its ability to be stored as a saturated liquid with inherently lower pressures as the constant volume system maintains self-equilibrium at saturation pressure. The associated laboratory safety of using a refrigerant propellant and ease of constructing cold-gas hardware make the propulsion system an ideal choice for low-budget satellite developers. The safety and performance analysis conducted on a general system indicates that with appropriate precautions and conservative design, test and analysis a refrigerant-based propulsion system can be safely implemented on small spacecraft and is a viable propulsion option. This feasibility study has been used as a guide to design and develop propulsion systems for each of the universities