Electrical time resolved metrology of dust particles growing in low pressure cold plasmas

2011 ◽  
Vol 18 (9) ◽  
pp. 093701 ◽  
Author(s):  
Gaëtan Wattieaux ◽  
Abdelaziz Mezeghrane ◽  
Laïfa Boufendi
Keyword(s):  
Low Pressure ◽  
Dust Particles ◽  
Time Resolved ◽  
Cold Plasmas

Numerical Investigation of Loss Development in a Low-Pressure Turbine Cascade With Unsteady Inflow and Varying Inlet Endwall Boundary Layer

2021 ◽  
Author(s):  
Tobias Schubert ◽  
Reinhard Niehuis
Keyword(s):  
Boundary Layer ◽  
Low Pressure ◽  
Turbine Cascade ◽  
Time Resolved ◽  
Blade Passage ◽  
Low Pressure Turbine ◽  
Wake Interaction ◽  
Spatial Redistribution ◽  
Unsteady Inflow ◽  
Flow Attenuation

Abstract An investigation of endwall loss development is conducted using the T106A low-pressure turbine cascade. (U)RANS simulations are complemented by measurements under engine relevant flow conditions (M2th = 0.59, Re2th = 2·105). The effects of unsteady inflow conditions and varying inlet endwall boundary layer are compared in terms of secondary flow attenuation downstream of the blade passage, analyzing steady, time-averaged, and time-resolved flow fields. While both measures show similar effects in the turbine exit plane, the upstream loss development throughout the blade passage is quite different. A variation of the endwall boundary layer alters the slope of the axial loss generation beginning around the midpoint of the blade passage. Periodically incoming wakes, however, cause a spatial redistribution of the loss generation with a premature loss increase due to wake interaction in the front part of the passage followed by an attenuation of the profile- and secondary loss generation in the aft section of the blade passage. Ultimately, this leads to a convergence of the downstream loss values in the steady and unsteady inflow cases.

Experimental Investigation of Vane Clocking in a One and 1/2 Stage High Pressure Turbine

2004 ◽  
Author(s):  
Charles W. Haldeman ◽  
Michael G. Dunn ◽  
John W. Barter ◽  
Brian R. Green ◽  
Robert F. Bergholz
Keyword(s):  
High Pressure ◽  
Low Pressure ◽  
Test Facility ◽  
Maximum Efficiency ◽  
High Pressure Turbine ◽  
Data Set ◽  
Time Resolved ◽  
Low Pressure Turbine ◽  
Turbine Vane ◽  
Vane Clocking

Aerodynamic measurements were acquired on a modern single-stage, transonic, high-pressure turbine with the adjacent low-pressure turbine vane row (a typical civilian one and one-half stage turbine rig) to observe the effects of low-pressure turbine vane clocking on overall turbine performance. The turbine rig (loosely referred to in this paper as the stage) was operated at design corrected conditions using the Ohio State University Gas Turbine Laboratory Turbine Test Facility (TTF). The research program utilized uncooled hardware in which all three airfoils were heavily instrumented at multiple spans to develop a full clocking dataset. The low-pressure turbine vane row (LPTV) was clocked relative to the high-pressure turbine vane row (HPTV). Various methods were used to evaluate the influence of clocking on the aeroperformance (efficiency) and the aerodynamics (pressure loading) of the LPTV, including time-resolved and time-averaged measurements. A change in overall efficiency of approximately 2–3% due to clocking effects is demonstrated and could be observed using a variety of independent methods. Maximum efficiency is obtained when the time-average surface pressures are highest on the LPTV and the time-resolved surface pressure (both in the time domain and frequency domain) show the least amount of variation. The overall effect is obtained by integrating over the entire airfoil, as the three-dimensional effects on the LPTV surface are significant. This experimental data set validates several computational research efforts that suggested wake migration is the primary reason for the perceived effectiveness of vane clocking. The suggestion that wake migration is the dominate mechanism in generating the clocking effect is also consistent with anecdotal evidence that fully cooled engine rigs do not see a great deal of clocking effect. This is consistent since the additional disturbances induced by the cooling flows and/or the combustor make it extremely difficult to find an alignment for the LPTV given the strong 3D nature of modern high-pressure turbine flows.

Recognition of Structures Leading to Transition in a Low Pressure Turbine Cascade: Effect of Reduced Frequency

2019 ◽  
Author(s):  
D. Lengani ◽  
D. Simoni ◽  
M. Ubaldi ◽  
P. Zunino ◽  
F. Bertini
Keyword(s):  
Boundary Layer ◽  
Suction Side ◽  
Low Pressure ◽  
Turbine Cascade ◽  
Turbulent Structures ◽  
Time Resolved ◽  
Low Pressure Turbine ◽  
Reduced Frequency ◽  
Displacement Thickness ◽  
Wake Passing

Abstract The boundary layer developing over the suction side of a low pressure turbine cascade operating under unsteady inflow conditions has been experimentally investigated. Time-resolved Particle Image Velocimetry (PIV) measurements have been performed in two orthogonal planes, the blade to blade and a wall parallel plane embedded within the boundary layer, for two different wake reduced frequencies. Proper Orthogonal Decomposition (POD) has been used to analyze the data and to provide an interpretation of the most significant flow structures for each phase of the wake passing cycle. To this purpose, a POD based procedure that sorts the data synchronizing the measurements of the two planes has been developed. Phase averaged data are then obtained for both cases. Moreover, once properly sorted, POD has been applied to sub-ensembles of data at the same relative phase within the wake passing cycle. Detailed information on the most energetic turbulent structures at a particular phase are obtained with this procedure (called phased POD), overcoming the limit of classical phase average that just provides a statistical representation of the turbulence field. Furthermore, the synchronization of the measurements in the two planes allows the computation of the characteristic dimension of boundary layer structures that are responsible for transition. These structures are often identified as vortical filaments parallel to the wall, typically referred to as boundary layer streaks. The largest and most energetic structures are observed when the wake centerline passes over the rear part of the suction side, and they appear practically the same for both reduced frequencies. The passing wake forces transition leading to the breakdown of the boundary layer streaks. Otherwise, the largest differences between the low and high reduced frequency are observed in the calmed region. The post-processing of these two planes further allowed us to compute the spacing of the streaks and make it non-dimensional by the boundary layer displacement thickness observed for each phase. The non-dimensional value of the streaks spacing is about constant, irrespective of the reduced frequency.

Simulation of the shielding of dust particles in low pressure glow discharges

1993 ◽  
Vol 62 (18) ◽  
pp. 2197-2199 ◽  
Author(s):  
Seung J. Choi ◽  
Mark J. Kushner
Keyword(s):  
Low Pressure ◽  
Dust Particles ◽  
Glow Discharges

Investigation of Air Ingress Into a Vacuum Vessel Related to Particle Re-Suspension and Distribution for Dust Issues in ITER

2017 ◽  
Author(s):  
Emmanuel Porcheron ◽  
Pascal Lemaitre
Keyword(s):  
Large Scale ◽  
Low Pressure ◽  
Normal Operation ◽  
Vacuum Vessel ◽  
Physical Processes ◽  
Time Resolved ◽  
Loss Of Coolant Accident ◽  
Image Velocimetry ◽  
Loss Of Coolant ◽  
Air Ingress

During normal operation of the ITER tokamak, few hundred kilograms of dust containing beryllium (Be) and tungsten (W) will be produced due to the erosion of the walls of the vacuum chamber by the plasma. During a loss of coolant accident (LOCA) or a loss of vacuum accident by air ingress (LOVA), hydrogen could be produced by dust oxidation with steam. Evaluation of the risk of dust and hydrogen explosion, that may lead to a loss of containment, requires studying the physical processes involved in the dust re-suspension and its distribution in the tokamak chamber. This experimental study is conducted by the Institut de Radioprotection et de Sûreté Nucléaire (IRSN) to simulate dust re-suspension phenomena induced by high velocity jet under low pressure conditions. Tests are conducted in a large scale facility (TOSQAN, 7 m3) able to reproduce primary vacuum conditions (1 mbar). Optical diagnostics such as PIV technique (Particles Image Velocimetry) are implemented on the facility to provide time resolved measurements of the dust re-suspension in terms of phenomenology and velocity. We present in this paper the TOSQAN facility with its configuration for studying dust re-suspension under low pressure conditions and underway experiments showing the mechanism of dust re-suspension by sonic and supersonic flows.

Blade–Row Interactions in a Low Pressure Turbine at Design and Strong Off-Design Operation

2014 ◽  
Vol 136 (11) ◽  
Author(s):  
Martin Lipfert ◽  
Jan Habermann ◽  
Martin G. Rose ◽  
Stephan Staudacher ◽  
Yavuz Guendogdu
Keyword(s):  
Experimental Data ◽  
Flow Field ◽  
Three Dimensional ◽  
Suction Side ◽  
Low Pressure ◽  
Test Facility ◽  
Time Resolved ◽  
Joint Project ◽  
Low Pressure Turbine ◽  
Blade Row

In a joint project between the Institute of Aircraft Propulsion Systems (ILA) and MTU Aero Engines, a two-stage low pressure turbine is tested at design and strong off-design conditions. The experimental data taken in the Altitude Test Facility (ATF) aims to study the effect of positive and negative incidence of the second stator vane. A detailed insight and understanding of the blade row interactions at these regimes is sought. Steady and time-resolved pressure measurements on the airfoil as well as inlet and outlet hot-film traverses at identical Reynolds number are performed for the midspan streamline. The results are compared with unsteady multistage computational fluid dynamics (CFD) predictions. Simulations agree well with the experimental data and allow detailed insights in the time-resolved flow-field. Airfoil pressure field responses are found to increase with positive incidence whereas at negative incidence the magnitude remains unchanged. Different pressure to suction side (SS) phasing is observed for the studied regimes. The assessment of unsteady blade forces reveals that changes in unsteady lift are minor compared to changes in axial force components. These increase with increasing positive incidence. The wake-interactions are predominating the blade responses in all regimes. For the positive incidence conditions, vane 1 passage vortex fluid is involved in the midspan passage interaction, leading to a more distorted three-dimensional (3D) flow field.

NH and CH laser-induced fluorescence in low-pressure flames: Quantum yields from time-resolved measurements

1989 ◽  
Vol 22 (1) ◽  
pp. 1867-1875 ◽  
Author(s):  
Karen J. Rensberger ◽  
Richard A. Copeland ◽  
Michael L. Wise ◽  
David R. Crosley
Keyword(s):  
Low Pressure ◽  
Laser Induced Fluorescence ◽  
Quantum Yields ◽  
Time Resolved ◽  
Time Resolved Measurements

Time-resolved CH (A^2Δ and B^2∑^−) laser-induced fluorescence in low pressure hydrocarbon flames

1988 ◽  
Vol 27 (17) ◽  
pp. 3679 ◽  
Author(s):  
Karen J. Rensberger ◽  
Mark J. Dyer ◽  
Richard A. Copeland
Keyword(s):  
Low Pressure ◽  
Laser Induced Fluorescence ◽  
Time Resolved ◽  
Hydrocarbon Flames
Sign in / Sign up

Export Citation Format

Share Document