Determination of Unsteady Heat Release Distribution in Unstable Combustor from Acoustic Pressure Measurements

1999 ◽  
Vol 15 (4) ◽  
pp. 613-616 ◽  
Author(s):  
Timothy C. Lieuwen ◽  
Yedidia Neumeier ◽  
Ben T. Zinn
Keyword(s):  
Heat Release ◽  
Acoustic Pressure ◽  
Pressure Measurements

Experimental Determination of the Tonal Noise Sources in a Centrifugal Fan

2003 ◽  
Author(s):  
Sandra Velarde-Sua´rez ◽  
Rafael Ballesteros-Tajadura ◽  
Carlos Santolaria-Morros ◽  
Juan Pablo Hurtado-Cruz
Keyword(s):  
Acoustic Pressure ◽  
Acoustic Radiation ◽  
Strong Dependence ◽  
Meridional Plane ◽  
Centrifugal Fan ◽  
Pressure Measurements ◽  
Tonal Noise ◽  
Noise Sources ◽  
Flow Rates

In this work, an experimental study about the aerodynamic tonal noise sources in an industrial centrifugal fan with backward-curved blades has been carried out. Acoustic pressure measurements at the fan exit duct and pressure fluctuation measurements on the volute surface (specially in the vicinity of the volute tongue) have been made for different flow rates. The correlation of both pressure signals can lead to determine the zone of effective acoustic radiation. As was expected, the tonal noise generation is concentrated on the meridional plane of the impeller discharge, near the volute tongue and presents a strong dependence with the flow rate.

Zur Thermodynamik der hydrophoben Wechselwirkung; die Systeme Wasser + Glycin+ Harnstoff und Wasser + Alanin+ Harnstoff bei 25 °C / Thermodynamics of Hydrophobie Interaction in the Systems Water + Glycin + Urea and Water + Alanin + Urea at 25 °C

1973 ◽  
Vol 28 (9-10) ◽  
pp. 533-554 ◽  
Author(s):  
Lothar Rafflenbeul ◽  
Wa-Ming Pang ◽  
Hansjürgen Schönert ◽  
Klaus Haberle
Keyword(s):  
Amino Acid ◽  
Magnetic Resonance ◽  
Proton Magnetic Resonance ◽  
Pressure Measurements ◽  
Free Enthalpy ◽  
Heat Of Dilution ◽  
Ternary Solutions ◽  
Vapor Pressure Measurements ◽  
Calorimetric Determination

Abstract Isopiestic vapor pressure measurements and calorimetric determination of the heat of dilution have been performed and evaluated with respect to enthalpy, entropy and free enthalpy in the ternary solutions water+ glycin+ urea and water+ alanin + urea. The free enthalpy of transfer for the process: Amino acid from water to water+ urea, which can be derived from these measurements, does not agree with the value calculated from solubility measurements. The reason for this discrepancy and the values of entropy and enthalpy in terms of hydrophobic interaction are discussed. Supplementary measurements of the proton magnetic resonance in these solutions are included.

Thermisches Verhalten von festem LaAlCl6 und chemischer Transport von LaCl3 mit AlCl3/Thermical Behaviour of Solid LaAlCl6 and Chemical Transport of LaCl3 with AlCl3

1999 ◽  
Vol 54 (11) ◽  
pp. 1410-1416 ◽  
Author(s):  
H. Oppermann ◽  
H. Dao Quoc ◽  
A. Morgenstern
Keyword(s):  
Total Pressure ◽  
Chemical Transport ◽  
Lanthanum Chloride ◽  
Pressure Measurements ◽  
Melting Diagram

The thermodynamical data of solid aluminium lanthanum chloride LaAlCl6 have been obtained by determination of the decomposition equilibria from total pressure measurements. The melting diagram was determined by DTA. The chemical transport of LaCl3 with AlCl3 is suggesting the existence of the gaseous complex LaAl3Cl12. The data are:ΔH(LaAlCl6f,298) =-427,1 ±2,5 kcal/mol, S°(LaAlCl6,f,298) = 61 ±2,5 cal/K-mol,Δ(LaAl3Cl12,g ,298) =-712 ± 7 kcal/mol, S°(LaAl3Cl12,g,298) = 205 ± 3 cal/K-mol.

Determination of in-plane permeability of fiber preforms by the gas flow method using pressure measurements

2003 ◽  
Vol 24 (1) ◽  
pp. 34-44 ◽  
Author(s):  
Sun K. Kim ◽  
Jeremy G. Opperer ◽  
Dae-Hwan Kim ◽  
Isaac M. Daniel
Keyword(s):  
Gas Flow ◽  
Pressure Measurements ◽  
Flow Method ◽  
Fiber Preforms

scholarly journals Flame Dynamics Intermittency in the Bi-Stable Region Near a Subcritical Hopf Bifurcation

2017 ◽  
Author(s):  
D. Ebi ◽  
A. Denisov ◽  
G. Bonciolini ◽  
E. Boujo ◽  
N. Noiray
Keyword(s):  
Heat Release ◽  
Heat Release Rate ◽  
Release Rate ◽  
Acoustic Pressure ◽  
Oscillation Amplitude ◽  
Stable Region ◽  
Describing Function ◽  
Acoustic Damping ◽  
Intermittent Behavior ◽  
Flame Describing Function

We report experimental evidence of thermoacoustic bi-stability in a lab-scale turbulent combustor over a well-defined range of fuel-air equivalence ratios. Pressure oscillations are characterized by an intermittent behavior with “bursts”, i.e. sudden jumps between low and high amplitudes occurring at random time instants. The corresponding probability density functions of the acoustic pressure signal show clearly separated maxima when the burner is operated in the bi-stable region. A flame describing function, which links acoustic pressure to heat release rate fluctuations, is estimated at the modal frequency from simultaneously recorded flame chemiluminescence and acoustic pressure. The representation of its statistics is new and particularly informative. It shows that this describing function is characterized, in average, by a nearly constant gain and by a significant drift of the phase as function of the oscillation amplitude. This finding suggests that the bi-stability does not result from an amplitude-dependent balance between flame gain and acoustic damping, but rather from the non-constant phase difference between the acoustic pressure and the coherent fluctuations of heat release rate.

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