Study of Coupling Numerical Flow Field Simulation of Low-Pressure Last Stage Exhaust Passage in Steam Turbine

2014 ◽  
Vol 672-674 ◽  
pp. 1626-1632
Author(s):  
Zhen Song ◽  
Jian Qun Xu ◽  
Li Peng Sun ◽  
Ming Tao Liu
Keyword(s):  
Flow Field ◽  
Steam Turbine ◽  
Turbulence Model ◽  
Pressure Loss ◽  
Total Pressure ◽  
Exhaust Hood ◽  
Coupled Models ◽  
Field Simulation ◽  
Inlet Swirl ◽  
Last Stage

The model of coupled exhaust hood with condenser throat and the model of coupled exhaust hood, condenser throat with last stage were simulated based on the turbulence model Realizable k-ε. Calculated results show that due to the ignoring of the inlet swirl in the model coupled exhaust hood with condenser throat, the flow field is symmetrical and the pressure loss is small. Due to the influence of last stage, in the model of coupled exhaust hood, condenser throat with last stage, the flow field of the inlet of the exhaust hood is uneven, and the vortexes changed more complex, resulting in the increase of the pressure loss of each part and a greater influence in the diffuser pipe. The proportion of pressure loss of diffuser pipe in total pressure loss increases from 0.086 to 0.358, and there is a 70% decline of proportion of pressure loss in volute and condenser throat. In addition, the proportion of the pressure loss in volute is the largest one in these two coupled models. So more attention should be paid in the influence of the last stage, and weaken the vortexes in the volute when designing or optimizing the exhaust passage of steam turbine.

Influence of a Cylindrical Exhaust Hood Installation on the Last Stage Rotor Blades of a Low Pressure Model Steam Turbine

2017 ◽  
Author(s):  
Fabian F. Müller ◽  
Markus Schatz ◽  
Damian M. Vogt ◽  
Jens Aschenbruck
Keyword(s):  
Flow Field ◽  
Steam Turbine ◽  
Operating Conditions ◽  
Rotor Blades ◽  
Pressure Measurements ◽  
Exhaust Hood ◽  
Blade Vibration ◽  
Time Resolved ◽  
Vibration Behavior ◽  
Last Stage

The influence of a cylindrical strut shortly downstream of the bladerow on the vibration behavior of the last stage rotor blades of a single stage LP model steam turbine was investigated in the present study. Steam turbine retrofits often result in an increase of turbine size, aiming for more power and higher efficiency. As the existing LP steam turbine exhaust hoods are generally not modified, the last stage rotor blades frequently move closer to installations within the exhaust hood. To capture the influence of such an installation on the flow field characteristics, extensive flow field measurements using pneumatic probes were conducted at the turbine outlet plane. In addition, time-resolved pressure measurements along the casing contour of the diffuser and on the surface of the cylinder were made, aiming for the identification of pressure fluctuations induced by the flow around the installation. Blade vibration behavior was measured at three different operating conditions by means of a tip timing system. Despite the considerable changes in the flow field and its frequency content, no significant impact on blade vibration amplitudes were observed for the investigated case and considered operating conditions. Nevertheless, time-resolved pressure measurements suggest that notable pressure oscillations induced by the vortex shedding can reach the upstream bladerow.

Unsteady Wet Steam Flow Field Measurements in the Last Stage of Low Pressure Steam Turbine

2015 ◽  
Author(s):  
Ilias Bosdas ◽  
Michel Mansour ◽  
Anestis I. Kalfas ◽  
Reza S. Abhari ◽  
Shigeki Senoo
Keyword(s):  
Flow Field ◽  
Steam Turbine ◽  
Total Pressure ◽  
Low Pressure ◽  
Operating Conditions ◽  
Test Facility ◽  
Flow Structures ◽  
Wet Steam ◽  
Operating Condition ◽  
Last Stage

Modern steam turbines need to operate efficiently and safely over a wide range of operating conditions. This paper presents a unique unprecedented set of time-resolved steam flowfield measurements from the exit of the last two stages of a low pressure (LP) steam turbine under various volumetric massflow conditions. The measurements were performed in the steam turbine test facility in Hitachi city in Japan. A newly developed fast response probe equipped with a heated tip to operate in wet steam flows was used. The probe tip is heated through an active control system using a miniature high-power cartridge heater developed in-house. Three different operating points, including two reduced massflow conditions, are compared and a detailed analysis of the unsteady flow structures under various blade loads and wetness mass fractions is presented. The measurements show that at the exit of the second to last stage the flow field is highly three dimensional. The measurements also show that the secondary flow structures at the tip region (shroud leakage and tip passage vortices) are the predominant sources of unsteadiness at 85% span. The high massflow operating condition exhibits the highest level of periodical total pressure fluctuation compared to the reduced massflow conditions at the inlet of the last stage. In contrast at the exit of the last stage, the reduced massflow operating condition exhibits the largest aerodynamic losses near the tip. This is due to the onset of the ventilation process at the exit of the LP steam turbine. This phenomenon results in 3 times larger levels of relative total pressure unsteadiness at 93% span, compared to the high massflow condition. This implies that at low volumetric flow conditions the blades will be subjected to higher dynamic load fluctuations at the tip region.

Experimental and Numerical Investigations of Steam Turbine Exhaust Hood Flow Field With Two Types of Diffusers

2019 ◽  
Author(s):  
Soichiro Tabata ◽  
Hisataka Fukushima ◽  
Kiyoshi Segawa ◽  
Koji Ishibashi ◽  
Yoshihiro Kuwamura ◽  
...  
Keyword(s):  
Flow Field ◽  
Flow Pattern ◽  
Steam Turbine ◽  
Three Dimensional ◽  
Internal Flow ◽  
Exhaust Hood ◽  
Scaled Model ◽  
Last Stage ◽  
Verification Test ◽  
Lp Turbine

Abstract The exhaust hood performance of LP turbine plays an important role in the efficiency of steam turbine. By improving the exhaust performance, the kinetic energy of the last stage rotating blades can be converted to the potential energy and it becomes possible to improve the turbine efficiency. However, the flow field in the diffuser is closely related to the flow pattern of the last stage rotating blade, and the flow field inside the exhaust chamber afterward has a complicated three dimensional flow field. Therefore, in this study, it conducted a scaled model steam turbine test using two types of diffusers and CFD, and evaluated exhaust performance and flow pattern. The verification test was carried out using a test turbine (4 stages) of × 0.33 scale, the velocity field and the pressure field were evaluated by traverse and the wall pressure measurements. The corresponding CFD was calculated by ANSYS CFX. All four stages of blades and seals, exhaust chambers were accurately modeled. Due to the detailed CFD, the internal flow of the exhaust chamber exhibiting complicated three-dimensionality was visualized and the flow pattern was evaluated. The verification test results and the corresponding CFD results were compared and evaluated, and it has been found that the overall performance predicted by CFD is well showing the verification test result. Therefore, it has been found that CFD can help to understand the internal flow of the exhaust chamber exhibiting complex three-dimensional characteristics.

Unsteady Wet Steam Flow Field Measurements in the Last Stage of Low Pressure Steam Turbine

2015 ◽  
Vol 138 (3) ◽  
Author(s):  
Ilias Bosdas ◽  
Michel Mansour ◽  
Anestis I. Kalfas ◽  
Reza S. Abhari ◽  
Shigeki Senoo
Keyword(s):  
Flow Field ◽  
Steam Turbine ◽  
Total Pressure ◽  
Low Pressure ◽  
Operating Conditions ◽  
Test Facility ◽  
Flow Structures ◽  
Wet Steam ◽  
Operating Condition ◽  
Last Stage

Modern steam turbines need to operate efficiently and safely over a wide range of operating conditions. This paper presents a unique unprecedented set of time-resolved steam flowfield measurements from the exit of the last two stages of a low pressure (LP) steam turbine under various volumetric massflow conditions. The measurements were performed in the steam turbine test facility in Hitachi city in Japan. A newly developed fast response probe equipped with a heated tip to operate in wet steam flows was used. The probe tip is heated through an active control system using a miniature high-power cartridge heater developed in-house. Three different operating points (OPs), including two reduced massflow conditions, are compared and a detailed analysis of the unsteady flow structures under various blade loads and wetness mass fractions is presented. The measurements show that at the exit of the second to last stage the flow field is highly three dimensional. The measurements also show that the secondary flow structures at the tip region (shroud leakage and tip passage vortices) are the predominant sources of unsteadiness at 85% span. The high massflow operating condition exhibits the highest level of periodical total pressure fluctuation compared to the reduced massflow conditions at the inlet of the last stage. In contrast at the exit of the last stage, the reduced massflow operating condition exhibits the largest aerodynamic losses near the tip. This is due to the onset of the ventilation process at the exit of the LP steam turbine. This phenomenon results in three times larger levels of relative total pressure unsteadiness at 93% span, compared to the high massflow condition. This implies that at low volumetric flow conditions the blades will be subjected to higher dynamic load fluctuations at the tip region.

A Novel Method of Coupling the Steam Turbine Exhaust Hood and the Last Stage Blades Using the Non-Linear Harmonic Method

2013 ◽  
Author(s):  
Zoe Burton ◽  
Grant Ingram ◽  
Simon Hogg
Keyword(s):  
Steam Turbine ◽  
Turbine Blades ◽  
Computation Time ◽  
Computational Effort ◽  
Alternative Methods ◽  
Test Case ◽  
Exhaust Hood ◽  
Harmonic Method ◽  
Non Linear ◽  
Last Stage

The exhaust hood of a steam turbine is a vital area of turbomachinery research its performance strongly influences the power output of the last stage blades. It is well known that accurate CFD simulations are only achieved when the last stage blades are coupled to the exhaust hood to capture the strong interaction. This however presents challenges as the calculation size grows rapidly when the full annulus is calculated. The size of the simulation means researchers are constantly searching of methods to reduce the computational effort without compromising solution accuracy. This work uses a novel approach, by coupling the last stage blades and exhaust hood by the Non-Linear Harmonic Method, a technique widely used to reduce calculation size in high pressure turbine blades and axial compressors. This has been benchmarked against the widely adopted Mixing Plane method. The test case used is the Generic Geometry, a representative exhaust hood and last stage blade geometry that is free from confidentiality and IP restrictions and for which first calculations were presented at last year’s conference [1]. The results show that the non-uniform exhaust hood inlet flow can be captured using the non-liner harmonic method, an effect not previously achievable with single passage coupled calculations such as the mixing plane approach. This offers a significant computational saving, estimated to be a quarter of the computation time compared with alternative methods of capturing the asymmetry with full annulus frozen rotor calculations.

The Pressure Field at the Output From a Low Pressure Exhaust Hood and Condenser Neck of the 1090 MW Steam Turbine: Experimental and Numerical Research

2018 ◽  
Author(s):  
Michal Hoznedl ◽  
Antonín Živný ◽  
Aleš Macálka ◽  
Robert Kalista ◽  
Kamil Sedlák ◽  
...  
Keyword(s):  
Boundary Condition ◽  
Steam Turbine ◽  
Cross Section ◽  
Static Pressure ◽  
Cooling Water ◽  
Low Pressure ◽  
Maximum Temperature ◽  
Angle Distribution ◽  
Exhaust Hood ◽  
Last Stage

The paper presents the results of measurements of flow parameters behind the last stage of a 1090 MW nominal power steam turbine in a nuclear power plant. The results were obtained by traversing a pneumatic probe at a distance of about 100 mm from the trailing edges of the LSB (Last Stage Blade). Furthermore, both side walls as well as the front wall of one flow of the LP (Low Pressure) exhaust hood were fitted with a dense net of static pressure taps at the level of the flange of the turbine. A total of 26 static pressures were measured on the wall at the output from the LP exhaust hood. Another 14 pressures were measured at the output from the condenser neck. The distribution of static pressures in both cross sections for full power and 600 and 800 MW power is shown. Another experiment was measured pressure and angle distribution using a ball pneumatic probe in the condenser neck area in a total of four holes at a distance up to 5 metres from the neck wall. The turbine condenser is two-flow design. In one direction perpendicular to the axis of the turbine cold cooling water comes, it heats partially. It then reverses and it heats to the maximum temperature again. The different temperature of cooling water in the different parts of the output cross section should influence the distribution of the output static pressure. Differences in pressures may cause problems with uneven load of the tube bundles of the condenser as well as problems with defining the influential edge output condition in CFD simulations of the flow of the cold end of the steam turbine Due to these reasons an extensive 3D CFD computation, which includes one stator blade as well as all moving blades of the last stage, a complete diffuser, the exhaust hood and the condenser neck, has been carried out. Geometry includes all reinforcing elements, pipes and heaters which could influence the flow behaviour in the exhaust hood and its pressure loss. Inlet boundary conditions were assumed for the case of both computations from the measurement of the flow field behind the penultimate stage. The outlet boundary condition was defined in the first case by an uneven value of the static pressure determined by the change of the temperature of cooling water. In the second case the boundary condition in accordance with the measurement was defined by a constant value of the static pressure along all the cross section of the output from the condenser neck. Results of both CFD computations are compared with experimental measurement by the distribution of pressures and other parameters behind the last stage.

Numerical Simulation of Cold Swirl Field for Solid Fuel Ramjet with NACA Airfoil

2014 ◽  
Vol 716-717 ◽  
pp. 711-716
Author(s):  
Jie Yu ◽  
Xiong Chen ◽  
Hong Wen Li
Keyword(s):  
Numerical Simulation ◽  
Flow Field ◽  
Radial Velocity ◽  
Solid Fuel ◽  
Velocity Gradient ◽  
Pressure Loss ◽  
Total Pressure ◽  
Swirl Flow ◽  
Total Pressure Loss ◽  
Swirl Number

In order to study the swirl flow characteristics in the solid fuel ramjet chamber, a new type of annular vane swirler with NACA airfoil is designed. The cold swirl flow field in the chamber is numerically simulated with different camber and t attack angle, while the swirl number , swirl flow field structure, total pressure recovery coefficient were studied. According to numerical simulation result, the main factors in swirl number are camber and angle of attack, the greater angle of attack, the greater the camber ,the stronger swirl will be. Results show that the total pressure loss is mainly concentrated in the inlet section, the total pressure loss cause by vane swirler is small. Radial velocity gradient exists in swirling flow, and increases with the swirl number. With the influence of centrifugal force and combustion chamber structure, the radial velocity gradient increases.

Numerical Simulation of Deposition Phenomena on High-Pressure Turbine Vane Using UPACS

2019 ◽  
Author(s):  
Kenta Mizutori ◽  
Koji Fukudome ◽  
Makoto Yamamoto ◽  
Masaya Suzuki
Keyword(s):  
Numerical Simulation ◽  
High Pressure ◽  
Flow Field ◽  
Pressure Loss ◽  
Total Pressure ◽  
Total Pressure Loss ◽  
High Pressure Turbine ◽  
Pressure Loss Coefficient ◽  
Turbine Vane ◽  
Total Pressure Loss Coefficient

Abstract We performed numerical simulation to understand deposition phenomena on high-pressure turbine vane. Several deposition models were compared and the OSU model showed good adaptation to any flow field and material, so it was implemented on UPACS. After the implementation, the simulations of deposition phenomenon in several cases of the flow field were conducted. From the results, particles adhere on the leading edge and the trailing edge side of the pressure surface. Also, the calculation of the total pressure loss coefficient was conducted after computing the flow field after deposition. The total pressure loss coefficient increased after deposition and it was revealed that the deposition deteriorates aerodynamic performance.

Sign in / Sign up

Export Citation Format

Share Document