Design, Analysis, Optimization and Control of Rotor Tip Flows

Developments in turbomachinery focus on efficiency and reliability enhancements, while reducing the production costs. In spite of the many noteworthy experimental and numerical investigations over the past decades, the turbine tip design presents numerous challenges to the engine manufacturers, and remains the primary factor defining the machine durability for the periodic removal of the turbine components during overhaul. Due to the hot gases coming from the upstream combustion chamber, the turbine blades are subjected to temperatures far above the metal creep temperature, combined with severe thermal stresses induced within the blade material. Inadequate designs cause early tip burnouts leading to considerable performance degradations, or even a catastrophic turbine failure. Moreover, the leakage spillage, nowadays often exceeding the transonic regime, generates large aerodynamic penalties which are responsible for about one third of the turbine losses. In this view, the current doctoral research exploits the potential through the modification and optimization of the blade tip shape as a means to control the tip leakage flow aerodynamics and manage the heat load distribution over the blade profile to improve the turbine efficiency and durability

Thematic clusters in the field of gas turbine thermal management: a co-word analysis during a century

The research aims to visualize and analyze the co-word network and thematic clusters of the intellectual structure in gas turbine thermal management during 1919-2020. The study is applied research in terms of the purpose, which is conducted with a descriptive approach, scientometrics indicators, techniques of co-word, and social network analysis. Data analysis and visualization of the co-word network were represented by VoS­Viewer, SPSS, UCINet, and python Software. The top scientific products in the last century were related to engineering subject area and published by the USA country. Seven main clusters were identified for the index keywords, and 20 main clusters were recognized for the author keywords in Scopus regarding the network structure and thematic clusters based on the co-occurrences. Moreover, 38 clusters were identified based on the hierarchical clusters. The clusters, namely heat flux calculations and radiation effects, thermal performance optimization, and operational considerations, have central and major positions in this field and have more potential to maintain and develop themselves in the future. The future of Research and Development (R&D) activities in the area will be focused on novel cycles, heat map development, and Techno-Economic and Risk Analysis (TERA) by utilizing systematic approaches for the identification of heat sinks and sources, fluid modeling, and environmental considerations. In addition, the emerging contributors in the field will be advanced manufacturing and material considerations

Secondary flow reduction techniques in linear turbine cascades

This thesis investigates a novel secondary flow reduction method. The inlet boundary layer to a linear turbine cascade is skewed by injection of air through an upstream slot to oppose regular generated negative stream wise vorticity. Other methods from the pertinent literature are reviewed on a broad basis. Detailed measurements of the flowfield in the Durham Linear Cascade facility have shown that substantial reductions in secondary flows and losses are possible. If the kinetic energy required for the blowing is taken into account by means of an availability analysis, no net gain in loss is achieved. Tests are performed at two different angles, of which the higher is typical for film cooling applications, and at a wide range of injection ratios. Calculation of the mixed-out losses show the tangential rather than spanwise momentum of the injected air is more effective in countering the generation of secondary flows. Computations using a state-of-the-art Navier-Stokes solver indicated shortcomings in modelling a flow governed by complex vortex dynamics. Improvements in the turbulence model and injection geometry could remedy this. The evaluation of turbulent and laminar production rates obtained without injection helps to explain total pressure loss generation mechanisms. The comparison of calculated and experimental eddy viscosities reveals the inadequacy of the Boussinesq assumption for high turning flows. The results obtained in this work are relevant to endwall film cooling applications. The tangential injection of air in front of the leading edge provides coolant in an optimum manner whilst possibly reducing secondary losses to a large extent. Disc cooling air, present in a real engine to prevent the ingestion of hot air from the mainstream, could be used to supply the injection

Gas Turbines

This book is intended to provide valuable information for the analysis and design of various gas turbine engines for different applications. The target audience for this book is design, maintenance, materials, aerospace and mechanical engineers. The design and maintenance engineers in the gas turbine and aircraft industry will benefit immensely from the integration and system discussions in the book. The chapters are of high relevance and interest to manufacturers, researchers and academicians as well

Aeronautical engineering: A continuing bibliography with indexes (supplement 271)

This bibliography lists 666 reports, articles, and other documents introduced into the NASA scientific and technical information system in October, 1991. 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

Aeronautical engineering, a continuing bibliography with indexes

This bibliography lists 823 reports, articles, and other documents introduced into the NASA scientific and technical information system in November 1984

Aeronautical Engineering: A continuing bibliography, 1982 cumulative index

This bibliography is a cumulative index to the abstracts contained in NASA SP-7037 (145) through NASA SP-7037 (156) 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, contract, and report number indexes

Aeronautical Engineering: A special bibliography with indexes, supplement 56

This bibliography lists 439 reports, articles, and other documents introduced into the NASA scientific and technical information system in March 1975

Energy: A continuing bibliography with indexes

This bibliography lists 1096 reports, articles, and other documents introduced into the NASA Scientific and Technical Information System from April 1, 1979 through June 30, 1979

Bibliography of Lewis Research Center technical publications announced in 1987

This compilation of abstracts describes and indexes the technical reporting that resulted from the scientific and engineering work performed and managed by the Lewis Research Center in 1987. All the publications were announced in the 1987 issues of STAR (Scientific and Technical Aerospace Reports) and/or IAA (International Aerospace Abstracts). Included are research reports, journal articles, conference presentations, patents and patent applications, and theses