Unsteady swirl distortion characteristics for S-ducts using Lattice Boltzmann and time-resolved, stereo PIV methods

The unsteady flowfields generated by convoluted aero engine intakes are major sources of instabilities that can compromise the performance of the downstream turbomachinery components. This highlights theneed for high spatial and temporal resolution measurements that will allow a greater understanding of the aerodynamics but also improvements in our current predictive capability for such complex flows. This paper presents the validation of a modern Lattice Boltzmann method (LBM)to predict the unsteady flow and swirl distortion characteristics within a representative S-duct intake.The numerical results are compared against high spatial and temporal resolutionParticle Image Velocimetry(PIV)data for the same S-duct configuration at an inlet Mach number of0.27.The work demonstrates that LBM is broadly able to capture the flow topologies and temporal characteristics with the exception of the magnitude of the unsteady fluctuations which were found to be notably under-predicted compared to the PIV data. Proper Orthogonal Decomposition analysis shows that LBM is able to provide the key flow modes and their spectral distributions which were found broadly in alignment with the PIV data. A statistical assessment of the unsteady distortionhistoryhighlights that LBM can also provide representative distributions of the main swirl distortion descriptors. Overall the work demonstrates that LBM shows promising potential for S-duct unsteady flow predictions which combined with the minimum computational grid requirements, robustness and fast convergence make it an attractive solution for wider use in thearea of unsteady propulsion system aerodynamics

Aeronautical Engineering: A special bibliography with indexes, supplement 61

This bibliography lists 418 reports, articles, and other documents introduced into the NASA scientific and technical information system in August 1975

Aeronautical engineering: A cumulative index to a continuing bibliography

This bibliography is a cumulative index to the abstracts contained in NASA SP-7037(210) through NASA SP-7037(221) of Aeronautical Engineering: A Continuing Bibliography. NASA SP-7037 and its supplements have been compiled through the cooperative efforts of the American Institute of Aeronautics and Astronautics (AIAA) and the National Aeronautics and Space Administration (NASA). This cumulative index includes subject, personal author, corporate source, foreign technology, contract number, report number, and accession number indexes

Aeronautical engineering: A continuing bibliography with indexes, supplement 140

This bibliography lists 386 reports, articles, and other documents introduced into the NASA scientific and technical information system in September 1981

High performance waterjets: study of an innovative scoop inlet and development of a novel method to design ducted propellers.

In the last decades the diffusion of waterjet systems for commercial applications in the high speed field is on the increase. These marine propulsors show remarkable qualities in terms of fuel consumption, noise, vibrations and manoeuvrability but they have some disadvantages which make their use optimal only for a limited speed range and which limit the overall propulsive efficiency. In the present document is described a way to modify a conventional waterjet with the aim of reducing these problems, increasing the overall efficiency. Many problems are dealt with. In chapter 3 it is shown how the substitution of a conventional flush inlet with a new scoop inlet could be an efficient way to minimise the total pressure losses and the non-uniformity velocity distribution upstream the pump, limiting in this way the influence of the boundary layer ingestion on the machine performance. In chapter 4 a novel method to study and design axial pumps is developed and explained. In chapter 5 a rim driven propeller is designed and tested numerically and experimentally demonstrating the good prediction capabilities of the method

Aeronautical Engineering: A continuing bibliography with indexes, supplement 108

This bibliography lists 517 reports, articles, and other documents introduced into the NASA scientific and technical information system in March 1979

Aeronautical engineering: A continuing bibliography with indexes (supplement 210)

This bibliography lists 409 reports, articles and other documents introduced into the NASA scientific and technical information system in January 1987

Aeronautical engineering: A continuing bibliography with indexes (supplement 237)

This bibliography lists 572 reports, articles, and other documents introduced into the NASA scientific and technical information system in February, 1989. Subject coverage includes: design, construction and testing of aircraft and aircraft engines; aircraft components, equipment and systems; ground support systems; and theoretical and applied aspects of aerodynamics and general fluid dynamics

Effect of swirl distortion on gas turbine operability

The aerodynamic integration of an aero-engine intake system with the airframe can pose some notable challenges. This is particularly so for many military air- craft and is likely to become a more pressing issue for both new military systems with highly embedded engines as well as for novel civil aircraft configurations. During the late 1960s with the advent of turbo-fan engines, industry became in- creasingly aware of issues which arise due to inlet total pressure distortion. Since then, inlet-engine compatibility assessments have become a key aspect of any new development. In addition to total temperature and total pressure distortions, flow angularity and the associated swirl distortion are also known to be of notable con- cern. The importance of developing a rigorous methodology to understand the effects of swirl distortion on turbo-machinery has also become one of the major concerns of current design programmes. The goal of this doctoral research was to further the current knowledge on swirl distortion, and its adverse effects on engine performance, focusing on the turbo-machinery components (i.e. fans or compressors). This was achieved by looking into appropriate swirl flow descriptors and by correlating them against the compressor performance parameters (e.g loss in stability pressure ratios). To that end, a number of high-fidelity three-dimensional Computational Fluid Dynamics (CFD) models have been developed using two sets of transonic rotors (i.e. NASA Rotor 67 and 37), and a stator (NASA Stator 67B). For the numerical purpose, a boundary condition methodology for the definition of swirl distortion patterns at the inlet has been developed. Various swirl distortion numerical parametric studies have been performed using the modelled rotor configurations. Two types of swirl distortion pattern were investigated in the research, i.e. the pure bulk swirl and the tightly-wound vortex. Numerical simulations suggested that the vortex core location, polarity, size and strength greatly affect the compressor performance. The bulk swirl simula- tions also showed the dependency on swirl strength and polarity. This empha- sized the importance of quantifying these swirl components in the flow distortion descriptors. For this, a methodology have been developed for the inlet-engine compatibility assessment using different types of flow descriptors. A number of correlations have been proposed for the two types of swirl distortion investigated in the study

Effect of swirl distortion on gas turbine operability

The aerodynamic integration of an aero-engine intake system with the airframe can pose some notable challenges. This is particularly so for many military air- craft and is likely to become a more pressing issue for both new military systems with highly embedded engines as well as for novel civil aircraft configurations. During the late 1960s with the advent of turbo-fan engines, industry became in- creasingly aware of issues which arise due to inlet total pressure distortion. Since then, inlet-engine compatibility assessments have become a key aspect of any new development. In addition to total temperature and total pressure distortions, flow angularity and the associated swirl distortion are also known to be of notable con- cern. The importance of developing a rigorous methodology to understand the effects of swirl distortion on turbo-machinery has also become one of the major concerns of current design programmes. The goal of this doctoral research was to further the current knowledge on swirl distortion, and its adverse effects on engine performance, focusing on the turbo-machinery components (i.e. fans or compressors). This was achieved by looking into appropriate swirl flow descriptors and by correlating them against the compressor performance parameters (e.g loss in stability pressure ratios). To that end, a number of high-fidelity three-dimensional Computational Fluid Dynamics (CFD) models have been developed using two sets of transonic rotors (i.e. NASA Rotor 67 and 37), and a stator (NASA Stator 67B). For the numerical purpose, a boundary condition methodology for the definition of swirl distortion patterns at the inlet has been developed. Various swirl distortion numerical parametric studies have been performed using the modelled rotor configurations. Two types of swirl distortion pattern were investigated in the research, i.e. the pure bulk swirl and the tightly-wound vortex. Numerical simulations suggested that the vortex core location, polarity, size and strength greatly affect the compressor performance. The bulk swirl simula- tions also showed the dependency on swirl strength and polarity. This empha- sized the importance of quantifying these swirl components in the flow distortion descriptors. For this, a methodology have been developed for the inlet-engine compatibility assessment using different types of flow descriptors. A number of correlations have been proposed for the two types of swirl distortion investigated in the study