Unsteady end-wall pressure measurements using near-field diy sensors on fouled fan rotor blade

The fouling is identifiable by the presence of dust on rotor and stator blades, and its main origin, in industrial turbomachinery, is the presence of a film of moist or lubricant driven to the trailing edge by the near-wall flow, or centrifuged toward the casing by impeller rotation. Solid particles pile up on them, leading to eccentricity and load unbalance. The formation of build-up results in performance reduction, and the chance of a deposit detachment while the impeller spun, may cause damages due to the impact on the machine parts. In industrial fans, the presence of fouling influences the characteristic curve and could anticipate stall when the flow rate is throttled. Rotating stall is an aerodynamic instability with a typical frequency about half the rotor frequency, acoustically identifiable from the changes in the emitted rotor noise, due to displacement from the stability. This work investigates rotating stall dynamics on an axial fan with fouled blades. The stall is identified with time-resolved pseudo-sound measurements in the end-wall region using DIY sensors. The signals have been analysed in frequency domain, and time domain using a phase space reconstruction technique. It is demonstrated a modification of the dynamic to stall and are identified diverse stall precursors

The Role of Couples\u27 Birth Experiences in Coparenting Dynamics During the Transition to Parenthood

Past research uncovered different antecedents, which influence the coparenting relationship including environmental supports and stressors, individual parent and child characteristics, and the couple relationship, though no prior study to date has investigated the impact of birth narratives on coparenting. The main purpose in the present study was to explore links between partners’ conjointly constructed birth narratives and coparenting dynamics preceding and following the birth of couples’ first child. Fifty-five couples’ coparenting interactions were observed during their last trimester of pregnancy (Prenatal Lausanne Trilogue Play) and at 3- (Postnatal Lausanne Trilogue play) and 12- months postpartum (Triadic play and mealtime interactions). At 3 months, couples were also asked to narrate the story of their child’s birth and of their early postpartum experience. Birth narratives were coded for narrative coherence, verbal and nonverbal emotional expressiveness, quality of coparenting, triadic capacity, and global views of the family and the coparenting relationship. Findings indicated that couples with more supportive prenatal and postpartum coparenting dynamics constructed more cohesive birth narratives at 3 months postpartum. Couples with more supportive prenatal and 3-months coparenting also expressed more positive emotions during their narratives, though these same associations were not found between positive expressiveness during birth stories and 12-months coparenting dynamics. A greater triadic focus during birth narratives was also associated with observed coparenting dynamics, though more commonly during concurrently observed interactions at 3 months rather than during prenatal or 12-months interactions. Findings suggest that birth narratives represent another paradigm which coparenting researchers should further explore to tap into the various contextual influences of coparenting across the transition to parenthood

Stall detection using near-field low frequency pressure modulation in turbomachines

This work investigates on the use of unconventional sensors to measure the near field unsteady pressure on the casing of a fan in a view to detect rotating stall. Rotating stall is an aerodynamic issue with a frequency signature usually half the rotor frequency. In low speed turbomachines, such as industrial fan, this turns in very low frequencies, even lower than 10 Hz. The authors developed and set-up a measurement system able to acquire low frequency pressure signals using dynamic microphones. Traditional methods use piezoelectric sensors, e.g. pressure transducers or microphones respectively in the near and far-field, to detect instability from the signal patterns with broad frequency ranges. Recently electret microphones have been proposed, but with a cut-off frequency of 20 Hz as such not suitable for signal in infrasound region. The sensor used in this work, have a narrower frequency range than more advanced technologies. In this paper the authors developed a measurement chain based on dynamic microphone and pressure transducer in order to create a stall warning system. They tested the system on a low speed axial fan and they validated the work against state of the art acoustic control techniques. For this reason those devices represent candidate solutions for the detection of the patterns typical of rotating stall in turbomachines.This work investigates on the use of unconventional sensors to measure the near field unsteady pressure on the casing of a fan in a view to detect rotating stall. Rotating stall is an aerodynamic issue with a frequency signature usually half the rotor frequency. In low speed turbomachines, such as industrial fan, this turns in very low frequencies, even lower than 10 Hz. The authors developed and set-up a measurement system able to acquire low frequency pressure signals using dynamic microphones. Traditional methods use piezoelectric sensors, e.g. pressure transducers or microphones respectively in the near and far-field, to detect instability from the signal patterns with broad frequency ranges. Recently electret microphones have been proposed, but with a cut-off frequency of 20 Hz as such not suitable for signal in infrasound region. The sensor used in this work, have a narrower frequency range than more advanced technologies. In this paper the authors developed a measurement chai

Stall Detection Using Pseudo-Acoustic Pressure Modulation in Industrial Fans

This work investigates the use of unconventional sensors to measure pressure modulation interpreted as pseudo sound in the near field on the casing of a fan in a view to detect rotating stall. Rotating stall is an aerodynamic issue with a frequency signature usually half the rotor frequency. In low speed turbomachines, such as industrial fans, this turns in very low frequencies, even lower than 10 Hz.Traditional methods use piezoelectric sensors, e.g., pressure transducers or microphones, respectively in the near and far-field, to detect instability from the signal patterns with broad frequency ranges. Recently electret microphones have been proposed, but with a cut-off frequency of 20 Hz as such not suitable for signal in near infrasound region.The sensor used in this work, have a narrower frequency range than more advanced technologies. The authors developed and set-up a measurement system able to acquire low frequency pressure signals using dynamic microphones.In this paper the authors developed a measurement chain based on dynamic microphone and pressure transducer in order to create a stall warning system. They tested the system on a low speed axial fan and they validated the work against state of the art acoustic control techniques. For this reason those devices represent candidate solutions for the detection of the patterns typical of rotating stall in turbomachines

A Critical Review of Stall Control Techniques in Industrial Fans

This paper reviews modelling and interpretation advances of industrial fan stall phenomena, related stall detection methods, and control technologies. Competing theories have helped engineers refine fan stability and control technology. With the development of these theories, three major issues have emerged. In this paper, we first consider the interplay between aerodynamic perturbations and instability inception. An understanding of the key physical phenomena that occurs with stall inception is critical to alleviate stall by design or through active or passive control methods. We then review the use of passive and active control strategies to improve fan stability. Whilst historically compressor design engineers have used passive control techniques, recent technologies have prompted them to install high-response stall detection and control systems that provide industrial fan designers with new insight into how they may detect and control stall. Finally, the paper reviews the methods and prospects for early stall detection to complement control systems with a warning capability. Engineers may use an effective real-time stall warning system to extend a fan's operating range by allowing it to operate safely at a reduced stall margin. This may also enable the fan to operate in service at a more efficient point on its characteristic

The alkaline transition of cytochrome c revisited: Effects of electrostatic interactions and tyrosine nitration on the reaction dynamics

Here we investigated the effect of electrostatic interactions and of protein tyrosine nitration of mammalian cytochrome c on the dynamics of the so-called alkaline transition, a pH- and redox-triggered conformational change that implies replacement of the axial ligand Met80 by a Lys residue. Using a combination of electrochemical, time-resolved SERR spectroelectrochemical experiments and molecular dynamics simulations we showed that in all cases the reaction can be described in terms of a two steps minimal reaction mechanism consisting of deprotonation of a triggering group followed by ligand exchange. The pK a alk values of the transition are strongly modulated by these perturbations, with a drastic downshift upon nitration and an important upshift upon establishing electrostatic interactions with a negatively charged model surface. The value of pK a alk is determined by the interplay between the acidity of a triggering group and the kinetic constants for the forward and backward ligand exchange processes. Nitration of Tyr74 results in a change of the triggering group from Lys73 in WT Cyt to Tyr74 in the nitrated protein, which dominates the pK a alk downshift towards physiological values. Electrostatic interactions, on the other hand, result in strong acceleration of the backward ligand exchange reaction, which dominates the pK a alk upshift. The different physicochemical conditions found here to influence pK a alk are expected to vary depending on cellular conditions and subcellular localization of the protein, thus determining the existence of alternative conformations of Cyt in vivo.Fil: Oviedo Rouco, Santiago. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Química, Física de los Materiales, Medioambiente y Energía. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Química, Física de los Materiales, Medioambiente y Energía; ArgentinaFil: Castro, Maria Ana. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Química, Física de los Materiales, Medioambiente y Energía. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Química, Física de los Materiales, Medioambiente y Energía; ArgentinaFil: Álvarez Paggi, Damián Jorge. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Química, Física de los Materiales, Medioambiente y Energía. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Química, Física de los Materiales, Medioambiente y Energía; ArgentinaFil: Spedalieri, Ana Cecilia. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Química, Física de los Materiales, Medioambiente y Energía. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Química, Física de los Materiales, Medioambiente y Energía; ArgentinaFil: Tortora, Verónica. Universidad de la República; UruguayFil: Tomasina, Florencia. Universidad de la República; UruguayFil: Radi, Rafael. Universidad de la República; UruguayFil: Murgida, Daniel Horacio. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Química, Física de los Materiales, Medioambiente y Energía. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Química, Física de los Materiales, Medioambiente y Energía; Argentin

Electron transfer and conformational transitions of cytochrome c are modulated by the same dynamical features

Cytochrome c is a prototypical multifunctional protein that is implicated in a variety of processes that are essential both for sustaining and for terminating cellular life. Typically, alternative functions other than canonical electron transport in the respiratory chain are associated to alternative conformations. In this work we apply a combined experimental and computational study of Cyt c variants to assess whether the parameters that regulate the canonical electron transport function of Cyt c are correlated with those that determine the transition to alternative conformations, using the alkaline transition as a model conformational change. The results show that pKa values of the alkaline transition correlate with the activation energies of the frictionally-controlled electron transfer reaction, and that both parameters are mainly modulated by the flexibility of the Ω-loop 70–85. Reduction potentials and non-adiabatic ET reorganization energies, on the other hand, are both modulated by the flexibilities of the Ω-loops 40–57 and 70–85. Finally, all the measured thermodynamic and kinetic parameters that characterize both types of processes exhibit systematic variations with the dynamics of the hydrogen bond between the axial ligand Met80 and the second sphere ligand Tyr67, thus highlighting the critical role of Tyr67 in controlling canonical and alternative functions of Cyt c.Fil: Oviedo Rouco, Santiago. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Química, Física de los Materiales, Medioambiente y Energía. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Química, Física de los Materiales, Medioambiente y Energía; ArgentinaFil: Perez Bertoldi, Juan Manuel. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Química, Física de los Materiales, Medioambiente y Energía. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Química, Física de los Materiales, Medioambiente y Energía; ArgentinaFil: Spedalieri, Ana Cecilia. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Química, Física de los Materiales, Medioambiente y Energía. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Química, Física de los Materiales, Medioambiente y Energía; ArgentinaFil: Castro, Maria Ana. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Química, Física de los Materiales, Medioambiente y Energía. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Química, Física de los Materiales, Medioambiente y Energía; ArgentinaFil: Tomasina, Florencia. Universidad de la República; UruguayFil: Tortora, Verónica. Universidad de la República; UruguayFil: Radi, Rafael. Universidad de la República; UruguayFil: Murgida, Daniel Horacio. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Química, Física de los Materiales, Medioambiente y Energía. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Química, Física de los Materiales, Medioambiente y Energía; Argentin