scholarly journals A study of the coarse water droplets formation in the nozzle

2019 ◽  
Vol 213 ◽  
pp. 02058
Author(s):  
Lucie Měšťanová ◽  
Ondřej Bartoš
Keyword(s):  
Wind Tunnel ◽  
Aqueous Solutions ◽  
High Speed ◽  
Liquid Films ◽  
Diameter Distribution ◽  
Settling Chamber ◽  
Steam Turbines ◽  
Water Droplets ◽  
Speed Flow ◽  
Negative Effect

The paper introduces the experimental results of the droplets formation for three different aqueous solutions. The new wind tunnel was built to study water droplets atomization from liquid films at high speed flow similar to that found in steam turbines. Liquid atomization is a widely studied problem for sprays and generally in the field of aerosol research. A similar phenomenon occurs in steam turbines but mainly with undesirable effects, the formed droplets from the film (coarse droplets) have a negative effect on the reliability and efficiency of the turbines due to the erosion and corrosion by the droplets impact on the leading edges of the blades. The new wind tunnel is equipped with classical pressure and temperature measurement systems for the determination of the initial condition in the settling chamber and measurement of the static pressure along the nozzle with a known profile. The photogrammetric method and light scattering are used to measure the diameter distribution of the droplets. The liquid film is made with an aqueous solution supplied on the symmetrical aerofoil NACA 0008. Different aqueous solutions were studied for different liquid surface tension effects.

scholarly journals AN EXPERIMENTAL STUDY OF THE COARSE DROPLETS FORMATION

2018 ◽  
Vol 20 ◽  
pp. 10-15
Author(s):  
Ondřej Bartoš ◽  
Lucie Měšťanová
Keyword(s):  
Experimental Study ◽  
Light Scattering ◽  
Wind Tunnel ◽  
Liquid Films ◽  
Diameter Distribution ◽  
Steam Turbines ◽  
Flow Conditions ◽  
Testing Facility ◽  
First Results ◽  
Negative Effect

The paper introduces the first results from a new steam/air wind tunnel built in order to study the coarse water droplets in steam turbines and their formation. The wind tunnel was designed with the aim to have a testing facility with similar flow conditions for the study of liquid films as found in steam turbines. The tunnel is equipped with common devices for the measurement of the flow and for the analysis of the diameter distribution of the droplets. Two measurements methods were used for the measurement of the droplets size, photogrammetry and light scattering. The liquid film is artificially produced on an airfoil placed in the nozzle and liquid is pumped by a dosing pump on the surface of the airfoil. Coarse droplets formed from the liquid films have a negative effect on the reliability and efficiency of the turbines due to the erosion and corrosion by the droplets impact on the leading edges of the blades.

scholarly journals AN ANALYSIS OF THE LIQUID FILMS BREAK-UP USING THE COMPUTER VISION TECHNIQUE

2021 ◽  
Vol 61 (1) ◽  
pp. 253-269
Author(s):  
Lucie Měšťanová ◽  
Ondřej Bartoš
Keyword(s):  
Image Processing ◽  
Wind Tunnel ◽  
High Speed ◽  
Optical Measurement ◽  
Liquid Films ◽  
Light Extinction ◽  
Steam Turbines ◽  
Droplet Distribution ◽  
Novel Approach ◽  
Unfavourable Effect

The aim of this paper is to introduce a novel approach for analysing the droplet formation in a transonic flow. The method suggested in this work is based on the combination of the measured data from the wind tunnel by an optical measurement and image processing. A new wind tunnel was developed for the study of the liquid film atomization at high speed flows similar to ones that can be found in steam turbines. The coarse droplets in steam turbines are formed from the liquid films on the blades and inner casings. The coarse droplets formed on the stator blades don´t follow the bulk flow and collide with the following moving blades. These collisions cause erosion and corrosion processes, which have an unfavourable effect on the reliability and the efficiency of the low pressure stages of steam turbines. The tunnel is equipped with a standard instrumentation for the measurement of the flow properties and for the analysis of the size distribution of the droplets. Two measurement methods were used for the measurement of the size of the droplets, photogrammetry and light scattering. In this paper, the image processing of the captured images is discussed. The images were taken by a camera with a telecentric lens. The paper contains an assessment of three image processing methods used for the measurement of the droplet distribution by the light extinction. Moreover, the formation of the droplets is captured on the trailing edge of the profile in the flow. The results bring a new view on the formation of droplets at high speeds.

scholarly journals A study of the electrostatic charge of the coarse water droplets

2021 ◽  
Vol 345 ◽  
pp. 00003
Author(s):  
Ondřej Bartoš ◽  
Václav Peter
Keyword(s):  
Liquid Phase ◽  
Wind Tunnel ◽  
Liquid Film ◽  
Thin Liquid Film ◽  
Electrical Current ◽  
Electrostatic Charge ◽  
Steam Turbines ◽  
Wet Steam ◽  
Water Droplets ◽  
Charging Mechanism

The aim of this paper is introduce the results of a measurement of the electrostatic charge of water droplets during wet steam expansion. The analysis of the charge origin was done. The achieved result shows that there is not a significant charging mechanism for the fine droplets. The dependence between the specific electrical current and the amount of liquid phase collected by the probe was found. Some models were studied to determine the origin of the electrical current. Finally a model was proposed, where the el. current is generated by the disruption of thin liquid film on the surface of the probe. The charging model was later applied for the measurement of the liquid film disruption in the new wind tunnel designed for the simulation of the flow field in the steam turbines. The measurement was performed with the air as a flowing medium and two modal droplets size distribution was found.

Flutter Limits and Behaviors of Flexible Webs Having a Simplified Basic Configuration in High-Speed Flow

2003 ◽  
Vol 125 (2) ◽  
pp. 345-353 ◽  
Author(s):  
Nobuyuki Yamaguchi ◽  
Keisuke Ito ◽  
Masayuki Ogata
Keyword(s):  
Wind Tunnel ◽  
High Speed ◽  
Bending Stiffness ◽  
High Speed Flow ◽  
Limit Values ◽  
Fluid Force ◽  
Reduced Frequency ◽  
Speed Flow ◽  
Trailing Edges ◽  
Basic Configuration

Fluttering conditions were analyzed for webs with a simplified basic configuration with both leading and trailing edges fixed in a uniform flow. The predicted flutter limits are expressed in terms of a ratio of fluid force to tension (σ*), a ratio of tension to bending stiffness (τ*), and a reduced frequency fR. Three characteristic zones of the behavior are seen to appear depending on the magnitude of τ*. For medium τ* of 1×103 to 1×106, flutter-limit values of σ* and fR remain nearly constant, respectively. For low τ*<1×103 effect of bending stiffness becomes significant and buckling-like instabilities tend to occur preceding the flutter. For high τ*>1×106 ripple-like modes tend to occur and σ* falls drastically and fR scatters much. Experimental flutter limits obtained in the wind tunnel were seen on the average to agree with the expected ones for the tested range of 9×102<τ*<4×104.

scholarly journals Aerospace Flight Modeling and Experimental Testing

2021 ◽  
pp. 131-147
Author(s):  
Olivier Chazot
Keyword(s):  
Wind Tunnel ◽  
Uncertainty Quantification ◽  
High Speed ◽  
Experimental Approach ◽  
Experimental Testing ◽  
Flow Conditions ◽  
High Speed Flow ◽  
Flow Physics ◽  
Speed Flow ◽  
Hypersonic Wind Tunnel

AbstractValidation processes for aerospace flight modeling require to articulate uncertainty quantification methods with the experimental approach. On this note, the specific strategies for the reproduction of re-entry flow conditions in ground-based facilities are reviewed. It shows how it combines high-speed flow physics with the hypersonic wind tunnel capabilities.

Visualization of High Speed Flow in a Pipe with Cavity

1997 ◽  
Vol 17 (Supplement2) ◽  
pp. 113-116
Author(s):  
Kenji HOSOI ◽  
Masaaki KAWAHASHI ◽  
Hiroyuki HIRAHARA ◽  
Kouju SHIOZAKI ◽  
Kenichirou SATOH
Keyword(s):  
High Speed ◽  
High Speed Flow ◽  
Speed Flow
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