STABILITY OF TURBINE BLADES, AIRCRAFT WINGS AND THEIR ACOUSTIC RADIATION

Ships and submarines are acoustic hazards to marine life. The rational control of acoustic radiation would be possible at least at low Reynolds numbers if the underlying organization buried in seeming randomness is revealed. We build a novel low-speed propulsor where all blades undergo small-amplitude pitch oscillation while spinning at large pitch angles at transitional chord Reynolds numbers (3.75 × 103 ≤ Rec ≤ 3.75 × 104) and advance ratios (0.51 ≤ J ≤ 4.89). We measure and model time-averaged and temporal thrust. The relationship between the time-averaged and the temporal thrust is observed when the latter is mapped as limit cycle oscillation (LCO), or departure from it. High-thrust coefficients occurring at large (30 deg and 45 deg) angles of amplitude of blade vibration are modeled assuming poststall lift enhancement due to flapping blades when a leading edge vortex (LEV) forms, while the lower thrust coefficients occurring at 20 deg are modeled by its absence. The disorganization in temporal thrust increases with J and Rec. An external orthogonal oscillator, perhaps a vibration, is modeled to couple with the thrust oscillator for temporal control of disorganization. The unfolding disorganization is seen as a departure from LCO, and it is attenuated by smooth-wall boundary-layer fencing, compared to unfenced smooth and rough surfaces. When the fencing properties of the leading edge tubercles of whale fins are recognized, the ratio of the spacing of the fences and chord is found to be similar (0.5–1.0) in both whale flippers and aircraft wings.

Download Full-text

An Investigation of the Flow in Manifolds with Open and Closed Ends

Journal of the Royal Aeronautical Society ◽

10.1017/s0001924000127812 ◽

1956 ◽

Vol 60 (551) ◽

pp. 749-753 ◽

Cited By ~ 9

Author(s):

J. H. Horlock

Keyword(s):

Gas Turbine ◽

Internal Combustion Engines ◽

Turbine Blades ◽

Internal Combustion ◽

Main Stream ◽

Combustion Engines ◽

Aircraft Wings ◽

Gas Turbine Blades ◽

Discharge Velocity ◽

Detailed Nature

The possibility of control of circulation around aircraft wings and gas turbine blades by ejection of air from the aerofoil into the main stream has drawn attention to the manifold problem. Discharge velocity distributions along the length of the wing or blade must be uniform, and it is important that the detailed nature of the flow in the supply manifolds should be understood. The distributions of velocity in manifolds supplying multicylinder internal combustion engines, in gas burners and in manifolds supplying canal locks are other allied problems.

Download Full-text

The Corrosion Properties of EN AW 7075 Aluminium Alloy in Power Industry

Materials Science Forum ◽

10.4028/www.scientific.net/msf.811.83 ◽

2014 ◽

Vol 811 ◽

pp. 83-87

Author(s):

Petra Lacková ◽

Maroš Halama ◽

Lukáš Dragošek ◽

Jana Cervová ◽

Marián Buršák ◽

...

Keyword(s):

Aluminium Alloy ◽

Aluminium Alloys ◽

Polarization Resistance ◽

Corrosion Potential ◽

Turbine Blades ◽

Power Industry ◽

Distilled Water ◽

Corrosion Properties ◽

Aircraft Wings ◽

Fatigue Characteristics

The study in this paper aimed on the corrosion properties of aluminium alloys used in the power industry. The corrosion characteristics were evaluated in the initial and state after severe plastic deformation of aluminium alloy AlZnMgCu. Due to the frequent interaction of fatigue failure accompanied corrosive failure (e.g. aircraft wings, turbine blades etc.) fatigue characteristics of selected alloy were evaluated. Standard corrosion characteristics such as corrosion potential, polarization resistance, corrosion rate and the corrosion products were evaluated for both states of an alloy in distilled water and SARS during exposition reaching 263 520 minutes.

Download Full-text

A porous edge on turbine blades and aircraft wings reduces noise production

Scilight ◽

10.1063/10.0005159 ◽

2021 ◽

Vol 2021 (22) ◽

pp. 221106

Author(s):

Anashe Bandari

Keyword(s):

Turbine Blades ◽

Aircraft Wings ◽

Noise Production

Download Full-text

Pulsation and Vibration Measurement on Stator Side for Turbocharger Turbine Blade Vibration Monitoring

International Journal of Turbomachinery Propulsion and Power ◽

10.3390/ijtpp5020011 ◽

2020 ◽

Vol 5 (2) ◽

pp. 11

Author(s):

Takashi Ando

Keyword(s):

Acoustic Radiation ◽

Measurement Techniques ◽

Turbine Blades ◽

Fuel Oil ◽

Vibration Monitoring ◽

Vibration Measurement ◽

Heavy Fuel Oil ◽

Blade Vibration ◽

Vibration Sensors ◽

Unburned Fuel

Mechanically robust turbine design with respect to blade vibration is challenging when dealing with nozzle-ring fouling and wear. Especially for engines operating with heavy fuel oil (HFO), the nozzle rings of the turbocharger turbines are prone to severe degradation in terms of contamination with unburned fuel deposits. This contamination will lead to an increased excitation of blade resonances in comparison to the nominal design. Due to the statistical character of contamination, long-term monitoring of blade vibration amplitudes would be beneficial. In the harsh environment of HFO operation, however, conventional blade vibration measurement techniques, such as those using strain gauges or blade tip timing, cannot work reliably for a long period. Thus, the objective of this research is to develop a method that enables the monitoring of turbine blades using pulsation or vibration sensors installed on the stator side. Almost a dozen turbines, both radial and axial, have been examined in order to determine a proper measurement chain/position and analytical method. Even though the challenges specific to the turbocharger turbine application—that high-frequency (up to 50 kHz) acoustic radiation from turbine blades has to be detected by a sensor on the stator side—were demanding, in the course of the investigations several clear examples of turbine blades engine-order resonance detection were gathered. Finally, the proposed method has been tested successfully in a power plant for over one year.

Download Full-text

Chemical partitioning of elements in Ni-base MC-carbide reinforced eutetic superalloys

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s042482010007504x ◽

1983 ◽

Vol 41 ◽

pp. 250-251

Author(s):

E. F. Koch ◽

E. L. Hall ◽

S. W. Yang

Keyword(s):

Alloy Composition ◽

Volume Fraction ◽

Lattice Mismatch ◽

Turbine Blades ◽

Eutectic Alloys ◽

Alloy Matrix ◽

X Ray ◽

Gas Turbine Blades ◽

Analytical Electron ◽

Analytical Electron Microscope

The plane-front solidified eutectic alloys consisting of aligned tantalum monocarbide fibers in a nickel alloy matrix are currently under consideration for future aircraft and gas turbine blades. The MC fibers provide exceptional strength at high temperatures. In these alloys, the Ni matrix is strengthened by the precipitation of the coherent γ' phase (ordered L12 structure, nominally Ni3Al). The mechanical strength of these materials can be sensitively affected by overall alloy composition, and these strength variations can be due to several factors, including changes in solid solution strength of the γ matrix, changes in they γ' size or morphology, changes in the γ-γ' lattice mismatch or interfacial energy, or changes in the MC morphology, volume fraction, thermal stability, and stoichiometry. In order to differentiate between these various mechanisms, it is necessary to determine the partitioning of elemental additions between the γ,γ', and MC phases. This paper describes the results of such a study using energy dispersive X-ray spectroscopy in the analytical electron microscope.

Download Full-text

Rationale Abklärung von Lebererkrankungen

Therapeutische Umschau ◽

10.1024/0040-5930/a000889 ◽

2017 ◽

Vol 74 (3) ◽

pp. 79-86

Author(s):

Leona von Köckritz ◽

Andrea De Gottardi

Keyword(s):

Acoustic Radiation ◽

Radiation Force ◽

Acoustic Radiation Force ◽

Acoustic Radiation Force Impulse ◽

Alkalische Phosphatase ◽

Gamma Glutamyltransferase ◽

Alpha 1 Antitrypsin

Zusammenfassung. Im klinischen Alltag werden häufig erhöhte Leberwerte beobachtet. In der Regel erfordern sie weitere Abklärungen bezüglich der möglichen Ätiologie und des Schweregrad einer akuten oder chronischen Lebererkrankung. Die Abklärung sollte dabei neben einer gezielten Anamnese und sorgfältigen klinischen Untersuchung, auch die Bestimmung von laborchemischen Markern für Cholestase und Leberfunktionsstörungen (wie Alkalische Phosphatase, gamma-Glutamyltransferase, Bilirubin, Albumin und Gerinnungsfaktoren) umfassen. Die Bestimmung weiterer Parameter wie Ferritin und Transferrinsättigung, Autoimmunantikörper, Virusserologien, alpha-1 Antitrypsin und Coerulolasmin können weitere Hinweise für die kausalen Zusammenhänge der Leberfunktionsstörung liefern. Bei Patienten mit Lebererkrankungen ist eine sonografische Beurteilung der Leber obligat. Ergänzend zur Sonografie werden heute weitere nicht-invasive Methoden wie Fibroscan, Acoustic Radiation Force Impulse Elastometrie und Magnet-Resonanz-Elastografie zur Beurteilung der Leberfibrose eingesetzt. In ausgewählten Fällen ist eine Leberbiopsie notwendig, um den Grad der Fibrose und die Ätiologie der Lebererkrankung zu eruieren. Mithilfe eines Fallbeispiels, diskutieren die Autoren im Folgenden die rationale Anwendung diagnostischer Tests und deren korrekte Interpretation und schlagen eine Orientierungshilfe zur rationalen Abklärung von Patienten mit Lebererkrankungen vor.

Download Full-text

Neue Horizonte bei der Lebersonographie

Praxis ◽

10.1024/1661-8157/a001112 ◽

2012 ◽

Vol 101 (18) ◽

pp. 1161-1166

Author(s):

Hagara ◽

Schwarzenbach ◽

Cerny

Keyword(s):

Acoustic Radiation ◽

Radiation Force ◽

Acoustic Radiation Force ◽

Acoustic Radiation Force Impulse

Dank technologischer Verbesserungen und einer immer besser werdenden klinischen Evidenzlage wird der diagnostische Ultraschall im Vergleich zu den Röntgen- und Magnetresonanzverfahren vermehrt eingesetzt. Dies nicht nur aus Kostengründen, sondern auch um der Zunahme der Strahlenbelastung der Bevölkerung durch diagnostische ionisierende Strahlen entgegenzuwirken. In der folgenden Übersichtsarbeit versuchen die Autoren die neuesten Entwicklungen im Bereich des Leberultraschalls vorzustellen. Bemerkenswert sind Verfahren, die eine dynamische Untersuchung der Leberdurchblutung mittels Kontrastmittelultraschall (Schwefelhexafluorid SonoVue®) und damit Verbesserungen bei der Charakterisierung von fokalen Leberläsionen wie Metastasen extrahepatischer Tumoren, Regeneratsknoten bei Leberzirrhose, fokaler nodulärer Hyperplasie, hepatozellu-lärem Karzinom, Leberhämangiom, Leberadenom sowie fokaler Mehr- oder Minderverfettung ermöglichen. Ebenfalls wichtig sind Techniken, die eine Bestimmung der Gewebekonsistenz mittels transienter Elastographie (Fibroscan), ARFI (Acoustic Radiation Force Impulse) oder Echtzeit-Gewebe-Elastographie erlauben. Die Quantifizierung des Steatosegrads ist für Diagnose und Verlaufsbeurteilung von Leberpathologien unabdingbar.

Download Full-text