Aeronautical engineering: A special bibliography with indexes, supplement 80

This bibliography lists 277 reports, articles, and other documents introduced into the NASA scientific and technical information system in January 1977

CFD investigation of a switched vortex valve for cooling air flow modulation in aeroengine

This thesis is focused on understanding the flow features associated with a Switched Vortex Valve (SVV) using Computational Fluid Dynamics (CFD) methods for application in aero-engines. In this research the major emphasis was put on detailed flow analysis which was limited in experimental studies of SVVs. Considering the complex geometry of the SVV, for simplicity it was decided to divide the SVV device into two parts before studying the device as whole. These parts are the vortex chamber and flow switching device, which together constitute the SVV device. In this research, different turbulence models were evaluated which are mainly Reynolds average Navier-Stokes (RANS) and unsteady Reynolds average NavierStokes (URANS). The different turbulence models are the k- , SA and the RSM, and for a test case LES was also implemented

Electrostatic Sensors – Their Principles and Applications

Over the past three decades electrostatic sensors have been proposed, developed and utilised for the continuous monitoring and measurement of a range of industrial processes, mechanical systems and clinical environments. Electrostatic sensors enjoy simplicity in structure, cost-effectiveness and suitability for a wide range of installation conditions. They either provide unique solutions to some measurement challenges or offer more cost-effective options to the more established sensors such as those based on acoustic, capacitive, optical and electromagnetic principles. The established or potential applications of electrostatic sensors appear wide ranging, but the underlining sensing principle and resultant system characteristics are very similar. This paper presents a comprehensive review of the electrostatic sensors and sensing systems that have been developed for the measurement and monitoring of a range of process variables and conditions. These include the flow measurement of pneumatically conveyed solids, measurement of particulate emissions, monitoring of fluidised beds, on-line particle sizing, burner flame monitoring, speed and radial vibration measurement of mechanical systems, and condition monitoring of power transmission belts, mechanical wear, and human activities. The fundamental sensing principles together with the advantages and limitations of electrostatic sensors for a given area of applications are also introduced. The technology readiness level for each area of applications is identified and commented. Trends and future development of electrostatic sensors, their signal conditioning electronics, signal processing methods as well as possible new applications are also discussed

Aeronautical Engineering: A continuing bibliography, supplement 120

This bibliography contains abstracts for 297 reports, articles, and other documents introduced into the NASA scientific and technical information system in February 1980

Aeronautical engineering: A continuing bibliography with indexes (supplement 119)

This bibliography lists 341 reports, articles, and other documents introduced into the NASA scientific and technical information system in January 1980. Abstracts on the engineering and theoretical aspects of design, construction, evaluation, testing, operation, and performance of aircraft (including aircraft engines) and associated components, equipment, and systems are presented. Research and development in aerodynamics, aeronautics, and ground support equipment for aeronautical vehicles are also presented

Acoustics Division recent accomplishments and research plans

The research program currently being implemented by the Acoustics Division of NASA Langley Research Center is described. The scope, focus, and thrusts of the research are discussed and illustrated for each technical area by examples of recent technical accomplishments. Included is a list of publications for the last two calendar years. The organization, staff, and facilities are also briefly described

Structural Mechanics Division research and technology plans for FY 1990 and accomplishments for FY 1989

The Objectives, FY 1990 Plans, Approach, and FY 1990 Milestones for the Structural Mechanics Division's research programs are presented. FY 1989 Accomplishments are presented where applicable. This information is useful in program coordination with other governmental organizations in areas of mutual interest

The aeroacoustics of jet pipes and cascades

This thesis is concerned with theoretical studies in two areas related to the noise of modern turbofan aeroengines. In the first case, we are concerned with the propagation of internally generated sound though the propulsion nozzle to the farfield, including the effects of diffraction by the jet pipe, refraction and Doppler amplification by the mean flow and the exchange of energy between acoustic and hydrodynamic modes at the nozzle lip. Both low and high frequencies are discussed. In the low frequency case, the essential aim is the derivation of simple analytical expressions and their interpretation in the context of various forms of acoustic analogy, and the analysis is continued to second order in a frequency parameter or Helmholtz number, giving predictions of the farfield directivity and of the magnitude of reflected waves in excellent agreement with experiments, and yet expressible in simple analytical fashion. An essential element of the solution of these problems is the satis¬faction of a Kutta condition at the nozzle lip. In the high frequency case, two approximate theories are formulated, and compared with each other and with exact solutions. The theories we handle are Kirchhoff's approximation and the geometric theory of diffraction. The aim is again to provide a theoretical framework in which as many effects as possible can be handled in a rational manner. The final two chapters are concerned with a particular aspect of compressor noise - the buzzsaw field generated by blading non--uniformities. This field is determined by the variation of shock strength of a non-uniform cascade. This is achieved by a combination of analysis of the detached shock waves ahead of a non-uniform cascade and a linear examination of the outflow from the cascade showing this to depend on area alone, at typical operating conditions, 'The upshot is a relation between the pressure rise across the shock wave ahead of the nth and (n - 1)th blades. This relation is in significantly better agreement with experiment than relations using attached shock waves, and provides a theoretical basis for blade shuffling procedures designed to alleviate buzzsaw noise. The aim throughout the thesis is to take the calculations as far as is possible and sensible by purely analytical means and to provide simple physical insight into the mechanisms involved