Investigation of flow through multi-stage restricting orifices

2017 ◽  
Vol 104 ◽  
pp. 75-90 ◽  
Author(s):  
Abdulrazaq A. Araoye ◽  
Hasan M. Badr ◽  
Wael H. Ahmed
Keyword(s):  
Multi Stage ◽  
Flow Through

Influence of Open and Closed Shroud Cavities on the Flowfield in a 2-Stage Turbine With Shrouded Blades

2003 ◽  
Author(s):  
Dieter E. Bohn ◽  
Ingo Balkowski ◽  
Hongwei Ma ◽  
Christian Tu¨mmers ◽  
Michael Sell
Keyword(s):  
Flow Field ◽  
Gas Turbines ◽  
Pressure Ratio ◽  
Axial Flow ◽  
Leading Edge ◽  
Operating Conditions ◽  
Complex Flow ◽  
Multi Stage ◽  
Flow Through ◽  
Insight Into

An important goal of the development of turbine bladings is to increase the efficiency for an optimized use of energy resources. This necessitates the most possible insight into the complex flow phenomena in multi-stage turbine bladings. This paper presents a combined numerical and experimental investigation of the flow field in a 2-stage axial turbine with shrouded blades, where the axial gap between the shroud and the endwall is varied between 1mm (closed cavities) and 5 mm (opened cavities). In the experimental setup at the Institute of Steam and Gas Turbines, Aachen University, the turbine is operated at a low pressure ratio of 1.4 with an inlet pressure of 3.2 bar. The rotating speed is adjusted by a water brake, which is integrated into a swing frame running in hydrostatic bearings. The rotor power dissipates in the water brake, which enables a very accurate angular momentum determination. The mass flow is measured through a calibrated nozzle installed upstream of the turbine inlet at an accuracy of better than 1%, from which stage efficiencies can be derived. For both geometric configurations (open and closed shroud cavities), the flow field at both inlet and outlet is measured using 5-hole probes as well as temperature probes at three operating conditions. The test rig is especially designed to investigate the influence of the cavity size. Therefore, the radial gaps between shroud and casing is held near zero in order to prevent an axial flow through the cavities. The experimental results are used as boundary conditions for corresponding numerical multi-stage calculations of the 3D flow through the 2-stage turbine, using the highly accurate steady Navier-Stokes inhouse computer code, CHT-Flow. The flow field measurements and the numerical simulations give deeper insight into some of the cavity-related flow field phenomena. The measurement results as well as the simulations indicate that the stator leading edge has little influence on the inlet flow field. The flow through the shroud cavities has a significant influence on the field and therefore on the machine’s performance.

Secondary Flow in Repeating Stages of Axial Turbomachines

1995 ◽  
Vol 209 (2) ◽  
pp. 101-110 ◽  
Author(s):  
J H Horlock
Keyword(s):  
Experimental Data ◽  
Secondary Flow ◽  
Flow Analysis ◽  
Axial Flow ◽  
Streamwise Vorticity ◽  
Flow Phenomenon ◽  
Multi Stage ◽  
Axial Velocity Profile ◽  
Flow Through ◽  
Flow Compressor

In a well-designed multi-stage axial flow compressor, the flow settles down to a repeating condition, in which the axial velocity profile does not deteriorate further; it is more or less unchanged between the entry and the exit of a deeply embedded stage. However, experimental data also show that the flow angles repeat, and it is this flow phenomenon that is discussed in the paper. Secondary flow analysis, coupled with empirical data on clearance flows, is used to give a description of the flow in such a repeating stage. The secondary flow at exit from a row involves both the streamwise vorticity generated in that row and the vorticity that exists at entry—the so-called ‘skew’ vorticity due to a non-uniform velocity from a stator being received by a moving rotor (and a similar effect from the rotor to the stator). However, clearance vorticity—shed from the rotor tip (casing) section and the stator root (hub) section—is also present and can be taken into account. Calculations made using the analyses are compared with some limited experimental data drawn from the published literature. Predicted underturning at rotor tip (casing) sections is confirmed by experiments; similarly, predicted underturning at stator tip (casing) sections accords with observations in one compressor but not in another. However, no universal conclusion (on whether underturning or overturning usually occurs) can be drawn for the flow through the rotor and stator root (hub) sections, as either entry or generated secondary vorticity may dominate.

Aerodynamics analysis of superheated steam flow through multi-stage perforated plates

2019 ◽  
Vol 141 ◽  
pp. 48-57 ◽  
Author(s):  
Jin-yuan Qian ◽  
Cong-wei Hou ◽  
Jia-yi Wu ◽  
Zhi-xin Gao ◽  
Zhi-jiang Jin
Keyword(s):  
Superheated Steam ◽  
Steam Flow ◽  
Perforated Plates ◽  
Multi Stage ◽  
Flow Through

Eulerian-Lagrangian Numerical Simulation of Wet Steam Flow Through Multi-Stage Steam Turbine

2013 ◽  
Author(s):  
Yasuhiro Sasao ◽  
Satoshi Miyake ◽  
Kenji Okazaki ◽  
Satoru Yamamoto ◽  
Hiroharu Ooyama
Keyword(s):  
Steam Turbine ◽  
Turbine Blades ◽  
Steam Flow ◽  
Droplet Growth ◽  
Computational Domain ◽  
Steam Turbines ◽  
Wet Steam ◽  
Multi Stage ◽  
Flow Through ◽  
Wet Steam Flow

In this paper, we present an inclusive tracking algorithm for water droplets in a wet steam flow through a multi-stage steam turbine. This algorism is based on the Eulerian-Lagrangian coupled solver. The solver continuously computes water droplet growth, kinematic non-equilibrium between vapor and droplets, capture and kinetics of droplets on turbine blades, departure of large droplets from the trailing edge of blades, acceleration and atomization of large droplets, and recollisions between blades and droplets. Our Eulerian-Lagrangian coupled solver is used to predict wetness in unsteady three-dimensional (3D) wet steam flows through three-stage stator rotor cascade channels in a low pressure (LP) steam turbine model which is developed by Mitsubishi Heavy Industries (MHI). Droplet groups tracked by the discrete droplet model (DDM) are placed in the computational domain according to the predicted wetness. Interference from the gas phase on the droplets is considered, to track their kinetic and behavior, until they reach the outlet of the computational domain. The aim of this research is to investigate those multi-physics phenomena that trigger all forms of loss in steam turbines. In addition, this method will also be applied to multi-physics problems such as erosion in future work. This paper is presented as a first step in the research. Overviews of model of current coupling solver and several test calculations are presented.

scholarly journals A Viscous Axisymmetric Throughflow Prediction Method for Multi-Stage Compressors

1992 ◽  
Author(s):  
Ahmet S. Ucer ◽  
Raymond P. Shreeve
Keyword(s):  
Secondary Flow ◽  
Axisymmetric Flow ◽  
Prediction Method ◽  
Computer Code ◽  
Equation Of Motion ◽  
Mixing Coefficient ◽  
Multi Stage ◽  
Multistage Compressors ◽  
Flow Through ◽  
Property Changes

This paper describes a computer code which solves viscous axisymmetric flow through multistage compressors. The code incorporates the modelling of 3-D effects which result from secondary flow and mixing and lead to property changes in the streamwise and spanwise directions. The method requires no extra data for loss, deviation and blockage. The necessary input data are the geometry, upstream stagnation conditions, rotational speed and mass flow rate. Blade wakes and their decay are modelled. The secondary flow component of the mixing coefficient modifies the uniform part and the result is used in the turbulent diffusion terms of the equation of motion. The P&W 3S1 low aspect ratio 3 stage compressor and UTRC 2 stage research compressor are used for validation. Considering the complexity of the flow in the multi-stage environment, it was concluded that the method gives encouraging results at a very economical rate.

Performance Analysis of a Low-Pressure Three-Stage Axial Compressor

2004 ◽  
Author(s):  
Sivakumar Subramanian ◽  
B. V. S. S. S. Prasad ◽  
S. Krishnan ◽  
C. Janakamma
Keyword(s):  
Three Dimensional ◽  
Axial Compressor ◽  
Low Pressure ◽  
Detailed Knowledge ◽  
Rotating Blade ◽  
Multi Stage ◽  
Challenging Tasks ◽  
Flow Features ◽  
Flow Through ◽  
Compressor Performance

Prediction of three-dimensional flow through a multi-stage axial compressor involving multiple frames of reference is one of the challenging tasks in CFD. When the axial gap between the stationary and rotating blade rows is reduced, the blade row interactions become important. Therefore, a detailed knowledge of flow features is essential for the optimum design of multi stage compressor. As the design and conduct of experiments and evaluation of compressor performance is expensive and time consuming, many aerospace industries prefer to obtain the same information by the computational efforts. In this context, a number of CFD codes for modelling and analysis of turbomachinery flows are used. The most exigent aspect of simulating multi-stage compressor is representing the interactions between the rotor and stator. The present work is to find out the best-suited method for the analysis of a low-pressure three-stage compressor that gives reliable results. The motivation for this effort is derived from the inability to consistently compare predicted performance parameters obtained from using the interface models with the experimental results, which is especially true for off-design operation.

Numerical simulation of gas flow through the flow part of a multi-stage turbomolecular vacuum pump

2020 ◽  
pp. 76-78 ◽  
Author(s):  
M.V. Fomin ◽  
O.R. Chernyishev
Keyword(s):  
Monte Carlo ◽  
Monte Carlo Method ◽  
Gas Flow ◽  
Pressure Ratio ◽  
Vacuum Pump ◽  
Maximum Pressure ◽  
Pump Impeller ◽  
Multi Stage ◽  
Turbomolecular Pump ◽  
Flow Through

The modeling of gas flow through a multi-stage flowing part of a turbomolecular vacuum pump to optimize the parameters of rotor and stator impeller wheels is considered. The developed program of statistical modeling by the Monte Carlo method allows us to determine the influence of the geometric parameters of the stages on the pump performance indicators. Keywords turbomolecular pump, impeller wheels, maximum action speed, maximum pressure ratio, Monte Carlo method. [email protected]

Development of Spanwise Velocity Profiles through Cascades and Axial-Flow Turbomachines

1968 ◽  
Vol 183 (1) ◽  
pp. 189-204 ◽  
Author(s):  
M. J. C. Swainston
Keyword(s):  
Velocity Profile ◽  
Family Relationship ◽  
Axial Flow ◽  
Point Of View ◽  
Incompressible Viscous Flow ◽  
Multi Stage ◽  
Flow Through ◽  
Work Done ◽  
Spanwise Velocity ◽  
The Way

The development of the spanwise velocity profile in the incompressible viscous flow through cascades is approached from a new point of view. This approach shows the way in which the cascade loading, the secondary losses, and the inlet-flow conditions interact to produce the downstream profile. The analysis leads to the establishment of a family relationship for experimentally occurring profiles. An empirical velocity-profile shape is determined which has the same properties as the experimental family, and this is used to demonstrate the way in which the mean secondary losses are distributed over the blade height. The profile development is studied in multi-stage machinery, and the formation of an equilibrium state after some few stages is shown. Work-done and blockage factors are computed for 50 per cent reaction compressor stages.

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