An attempt to make a reliable assessment of the wet steam flow field in the de Laval nozzle

In the frame of the measurement feasibility study of the liquid phase size distribution structure in steam turbines at intermediate and high pressures, on CTU the interaction of optical probes with the wet steam flow field is investigated. In order to validate and refine the existing knowledge, a new series of CFD simulations were performed, considering turbine flow geometry, water steam characteristics according to IAPWS97 formulation, and improved boundary conditions and quality of the computing mesh. This paper briefly presents the newly obtained results

Download Full-text

The Effects of Water Injections in Wet Steam Flow in Different Regions of a Mini Laval Nozzle

ASME 2008 6th International Conference on Nanochannels, Microchannels, and Minichannels ◽

10.1115/icnmm2008-62252 ◽

2008 ◽

Author(s):

M. R. Mahpeykar ◽

E. Amirirad ◽

E. Lakzian

Keyword(s):

Nucleation Rate ◽

Laval Nozzle ◽

Pressure Rise ◽

Steam Flow ◽

Steam Turbines ◽

Wet Steam ◽

Water Droplets ◽

Two Phase ◽

Condensation Shock ◽

Wet Steam Flow

Progress in the development of the steam turbines brings about a renewal of interest in wetness associated problems. In turbine steam expansion, the vapour first supercools and then condenses spontaneously to become a two phase mixture. The flow initially is single phase but after Wilson point water droplets are developed and there is a non equilibrium two phase flow. The formation and behavior of the liquid create problems that lower the performance of the turbine wet stage and the mechanisms underlying this are insufficiently understood. This growing droplets release their latent heat to the flow and this heat addition to the supersonic flow cause a pressure rise called condensation shock. Because of irreversible heat transfer in this region the entropy will increase tremendously. Removal of condensates from wet steam flow in the last stage of steam turbines significantly promotes stage efficiency and prevents erosion of rotors. The following study investigates the spraying water droplets at inlet and at throat of mini Laval nozzle and their effects on nucleation rate and condensation shock. According to the results, the nucleation rate is considerably suppressed and therefore the condensation shock nearly disappeared. In other words the injecting droplets would decrease the thermodynamic losses or improve the turbine efficiency.

Download Full-text

Investigation of wet steam flow in a 300 MW direct air-cooling steam turbine. Part 2: Flow field and windage

Proceedings of the Institution of Mechanical Engineers Part A Journal of Power and Energy ◽

10.1243/09576509jpe811 ◽

2009 ◽

Vol 224 (1) ◽

pp. 129-137 ◽

Cited By ~ 3

Author(s):

X Cai ◽

F Niu ◽

J Li ◽

M Su ◽

T Ning ◽

...

Keyword(s):

Flow Field ◽

Steam Turbine ◽

Steam Flow ◽

Air Cooling ◽

Wet Steam ◽

Wet Steam Flow

Download Full-text

Wet steam flow and condensation loss in turbine blade cascades

Applied Thermal Engineering ◽

10.1016/j.applthermaleng.2021.116748 ◽

2021 ◽

Vol 189 ◽

pp. 116748

Author(s):

Chuang Wen ◽

Yan Yang ◽

Hongbing Ding ◽

Chunqian Sun ◽

Yuying Yan

Keyword(s):

Turbine Blade ◽

Steam Flow ◽

Wet Steam ◽

Wet Steam Flow

Download Full-text

Some Experiments on Wet Steam Flow Visualization in Large Steam Turbine Blading

Journal of Fluids Engineering ◽

10.1115/1.3448403 ◽

1976 ◽

Vol 98 (3) ◽

pp. 573-577 ◽

Cited By ~ 1

Author(s):

J. Krzyz˙anowski ◽

B. Weigle

Keyword(s):

Steam Turbine ◽

Steam Flow ◽

Light Sources ◽

Phase Flow ◽

Wet Steam ◽

Experimental Conditions ◽

Advantages And Disadvantages ◽

Primary Droplet ◽

Last Stage ◽

Wet Steam Flow

In a series of experiments aimed at the visualization of the wet steam flow in the exhaust part of a 200 MW condensing steam turbine a set of periscopes and light sources was used. The aim of the experiment was: 1 – The investigation of the liquid-phase flow over the last stage stator blading of the turbine mentioned. 2 – The investigation of the gaseous-phase flow through the last stage blading at full and part load. The first part of the program partially failed due to the opaqueness of the wet steam atmosphere for the turbine load higher than 10–20 MW. The detailed experimental conditions will be described. An assessment of the primary droplet size will also be given. The preliminary results of the second part of the program will be outlined. The advantages and disadvantages of the equipment used will be discussed.

Download Full-text