MEE-DBD Plasma Actuator Effect on Aerodynamics of a NACA0015 Aerofoil: Separation and 3D Wake

© 2020, Springer Nature Switzerland AG. Dielectric barrier discharge (DBD) plasma actuators have received considerable attention by many researchers for various flow control applications. Having no moving parts, being light-weight, easily manufacturable, and their ability to respond almost instantly are amongst the advantages which has made them a popular flow control device especially for application on aircraft wings. The new configuration of DBDs which uses multiple encapsulated electrodes (MEE) has been shown to produce a superior and more desirable performance over the standard actuator design. The objective of the current study is to examine the effect of this new actuator configuration on the aerodynamic performance of an aerofoil under leading edge separation and wake interaction conditions. The plasma actuator is placed at the leading edge of a symmetric NACA 0015 aerofoil which corresponds to the location of the leading edge slat. The aerofoil is operated in a chord Reynolds number of 0.2×106. Surface pressure measurements along with the mean velocity profile of the wake using pitot measurements are used to determine the lift and drag coefficients, respectively. Particle image velocimetry (PIV) is also utilised to visualise and quantify the induced flow field. The results show improvement in aerodynamic performances of aerofoil under leading edge separation and also facing the wake region

Active flow control at a 1.5-stage low-speed research compressor with varying rotor tip clearance

The stable operating range of axial compressors is limited by the onset of rotating stall and surge. Mass injection upstream of the tip of an axial compressor rotor is a stability enhancement approach which can be effective in suppressing stall in tip-critical rotors, and thus increasing the operating range of compressors. In this article, investigations on active flow control related to the rotor tip gap sensitivity are discussed. The experiments were performed in a 1.5-stage low-speed research compressor. Measurements at part speed (80 per cent) and full speed (100 per cent) with varying injection rates are discussed. These tests were performed for two rotor tip clearances of 1.3 per cent and 4.3 per cent of rotor blade tip chord. Results on the compressor map, the flow field as well as transient measurements to identify the stall inception are discussed. Supplementary, the numerical results are compared to the experiments based on the configuration with the greatest benefit in operating range enhancement

Modal decomposition for the analysis of the rotor-stator interactions in multistage compressors

International audienc

Verbesserung von Stroemungsstabilitaet und Betriebssicherheit, Laermreduktion. Teilvorhaben 1.243: Frueherkennung rotierender Instabilitaeten Abschlussbericht

The performance of compressors of stationary gas turbines and aircraft gas turbines is reduced near the stability limit due to compressor instabilities. This may lead to low performance and even to blade damage, so that a stall margin is maintained in general which reduces the working potential of the compressor. Early detection of aerodynamic instabilities and return to a stable flow state is the basis for extending the operating range of compressors. The project intends to provide a better understanding of the mechanisms leading to the development of compressor instabilities, so that criteria for early detection of rotary stall can be developedDas Betriebsverhalten von Verdichtern von stationaeren Gasturbinen und Flugtriebwerken wird bei Annaeherung des Betriebsregimes an die Stabilitaetsgrenze durch Verdichterinstabilitaeten eingeschraenkt. Diese instationaere Stroemungszustaende gefaehrden die Betriebsweise entscheidend und koennen aufgrund angeregter Schwingungen zu Schaeden an der Beschauflung fuehren. Aus diesem Grund wird beim Betrieb von Verdichtern ein Abstand zwischen dessen Arbeitslinie und der Stabilitaetsgrenze eingehalten (Pumpgrenzabstand, stall margin), der das Arbeitspotential des Verdichters verringert. Die Frueherkennung aerodynamischer Instabilitaeten und die Rueckfuehrung des Betriebsregimes in einen stabilen Stroemungszustand bildet die Grundlage fuer eine kuenftige Erweiterung des Arbeitsbereiches von Verdichtern. Ziel dieses Vorhabens ist die Verbesserung des Verstaendnisses der Entstehnungsmechanismen von Verdichterinstabilitaeten. Daraus koennen Kriterien entwickelt werden, die zur Frueherkennung von Rotierender Abloesung dienen. Dadurch wird ein Beitrag zur Erweiterung des Betriebsbereiches und zur Verbesserung der Betriebssicherheit von Turbomaschinen moeglich. (orig.)SIGLEAvailable from TIB Hannover: F00B367 / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekBundesministerium fuer Bildung und Forschung (BMBF), Bonn (Germany)DEGerman

Effect of clocking on unsteady rotor blade loading in a low-speed axial compressor at design and off-design operating conditions

This paper presents the results of stator clocking investigations at a design point and an operating point near the stability limit in a low-speed research compressor (LSRC). The unsteady flow field of the LSRC at several clocking configurations was investigated using a three-dimensional unsteady, viscous solver. The unsteady pressure on the rotor blades at midspan (MS) was measured using time-resolving piezoresistive miniature pressure transducers. The effect of clocking on the unsteady pressure fluctuation at MS on the rotor blades is discussed for different operating points. Based on the unsteady profile pressures, the blade pressure forces were calculated. The peak-to-peak amplitudes of the unsteady blade pressure forces are presented and analysed for different clocking positions at both the design point and the operating point near the stability limit of the compressor