Effect of Stage Axial Distances on the Aerodynamic Performance of Three-Stage Axial Turbine Using Experimental Measurements and Numerical Simulations

2017 ◽  
Author(s):  
Yang Chen ◽  
Zhuhai Zhong ◽  
Jun Li ◽  
Weijiu Zhou ◽  
Gangyun Zhong ◽  
...  
Keyword(s):  
Flow Field ◽  
Numerical Simulations ◽  
Velocity Ratio ◽  
Aerodynamic Performance ◽  
Navier Stokes ◽  
Experimental Measurements ◽  
Axial Distance ◽  
Axial Turbine ◽  
Air Turbine ◽  
Aerodynamic Parameters

The stage axial distance significantly influences the aerodynamic performance of turbines under some constraints. Experimental measurements and numerical simulations are used to analyze the effect of stage axial distances on the aerodynamic performance of three-stage axial turbine in this work. The aerodynamic performance of three-stage axial turbine with three different stage axial distances is experimentally measured at the air turbine test rig of Dongfang Steam Turbine Co. LTD. Experimental results show that efficiency increases when the stage axial distance decreases for the geometry under study with relative stage distance ranged from 0.14 to 0.35, and the effect of stage axial distance on the optimization velocity ratio here is very limited. In addition, unsteady Reynolds-Averaged Navier-Stokes (RANS) simulations were carried out with nonlinear harmonic method to analyze the detailed flow field of the experimental three-stage axial turbine. The numerical aerodynamic efficiency of three-stage axial turbine is in good agreement with the experimental data. Furthermore, the small stage axial distance is preferred for the higher efficiency. The detailed flow field and aerodynamic parameters of three-stage axial turbine are also illustrated and discussed.

Shock Waves and Plume Prediction of a Rocket Thruster With an Attached Panel

2003 ◽  
Author(s):  
Farhad Davoudzadeh ◽  
Nan-Suey Liu
Keyword(s):  
Supersonic Flow ◽  
Shock Waves ◽  
Flow Field ◽  
Numerical Simulations ◽  
Operating Conditions ◽  
Navier Stokes ◽  
Experimental Measurements ◽  
Pressure Distributions ◽  
Temperature And Pressure ◽  
Reynolds Averaged Navier Stokes

Reynolds-Averaged Navier-stokes (RANS) numerical simulations are performed to predict the supersonic flow field induced by a H2-O2 rocket thruster with an attached panel, under a variety of operating conditions. The simulations have captured physical details of the flow field, such as the plume formation and expansion, formation of a system of shock waves and their effects on the temperature and pressure distributions on the walls. Comparison between the computed results for 2-D and adiabatic walls and the related experimental measurements for 3-D and cooled walls shows that the results of the simulations are consistent with those obtained from the related rig tests.

Unsteady Interaction of Labyrinth Seal Leakage Flow and Downstream Stator Flow in a Shrouded 1.5 Stage Axial Turbine

2005 ◽  
Author(s):  
P. Peters ◽  
J. R. Menter ◽  
H. Pfost ◽  
A. Giboni ◽  
K. Wolter
Keyword(s):  
Flow Field ◽  
Three Dimensional ◽  
Numerical Data ◽  
Labyrinth Seal ◽  
Rotor Blades ◽  
Navier Stokes ◽  
Experimental Program ◽  
Leakage Flow ◽  
Axial Turbine ◽  
Flow Phenomena

This paper presents the results of experimental and numerical investigations into the flow in a 1.5-stage low-speed axial turbine with shrouded rotor blades and a straight through labyrinth seal. The paper focuses on the time dependent influence of the leakage flow on the downstream stator flow field. The experimental program consists of time accurate measurements of the three-dimensional properties of the flow through ten different measurement planes in the stator passage. The measurements were carried out using pneumatic five-hole probes and three dimensional hot-wire probes at the design operating point of the turbine. The measurement planes extend from the shroud to the casing. The complex three-dimensional flow field is mapped in great detail by 4,800 measurement points and 20 time steps per blade passing period. The time-accurate experimental data of the ten measurement planes was compared with the results of unsteady, numerical simulations of the turbine flow. The 3D-Navier-Stokes Solver CFX-TASCflow was used. The experimental and numerical results correspond well and allow detailed analysis of the flow phenomena. Additionally numerical data behind the rotor is used to connect the entry of the leakage flow with the flow phenomena in the downstream stator passage and behind it. The leakage flow causes strong fluctuations of the flow in the downstream stator. Above all, the high number of measurement points reveals both the secondary flow phenomena and the vortex structures within the blade passage. The time-dependence of both the position and the intensity of the vortices influenced by the leakage flow is shown. The paper shows that even at realistic clearance heights the leakage flow influences considerable parts of the downstream stator and gives rise to negative incidence and flow separation. Thus, labyrinth seal leakage flow should be taken properly into account in the design or optimization process of turbines.

URANS Simulation of an Appended Hull During Steady Turn With Propeller Represented by an Actuator Disk Model

2011 ◽  
Author(s):  
Charles M. Dai ◽  
Ronald W. Miller
Keyword(s):  
Flow Field ◽  
Cross Flow ◽  
Field Measurements ◽  
Navier Stokes ◽  
Experimental Measurements ◽  
Complex Flow ◽  
Ship Maneuvering ◽  
Disk Model ◽  
Actuator Disk ◽  
Propeller Wake

This paper reports on the comparison between computational simulations and experimental measurements of a surface vessel in steady turning conditions. The primary purpose of these efforts is to support the development of physics-based high fidelity maneuvering simulation tools by providing accurate and reliable hydrodynamic data with relevance to maneuvering performances. Reynolds Averaged Unsteady Navier Stokes Solver (URANS): CFDSHIPIOWA was used to perform simulations for validation purposes and for better understanding of the fundamental flow physics of a hull under maneuvering conditions. The Propeller effects were simulated using the actuator disk model included in CFDShip-Iowa. The actuator disk model prescribes a circumferential averaged body force with axial and tangential components. No propeller generated side forces are accounted for in the model. This paper examines the effects of actuator disk model on the overall fidelity of a RANS based ship maneuvering simulations. Both experiments and simulations provide physical insights into the complex flow interactions between the hull and various appendages, the rudders and the propellers. The experimental effort consists of flow field measurements using Stereo Particle-Image Velocimetry (SPIV) in the stern region of the model and force and moment measurements on the whole ship and on ship components such as the bilge keels, the rudders, and the propellers. Comparisons between simulations and experimental measurements were made for velocity distributions at different transverse planes along the ship axis and different forces components for hull, appendages and rudders. The actuator disk model does not predict any propeller generated side forces in the code and they need to be taken into account when comparing hull and appendages generated side forces in the simulations. The simulations were compared with experimental results and they both demonstrate the cross flow effect on the transverse forces and the propeller slip streams generated by the propellers during steady turning conditions. The hull forces (include hull, bilge keels, skeg, shafting and strut) predictions were better for large turning circle case as compared with smaller turning circle. Despite flow field simulations appear to capture gross flow features qualitatively; detailed examinations of flow distributions reveal discrepancies in predictions of propeller wake locations and secondary flow structures. The qualitative comparisons for the rudders forces also reveal large discrepancies and it was shown that the primary cause of discrepancies is due to poor predictions of velocity inflow at the rudder plane.

Simulation of Three-Dimensional Viscous Flow Within a Multistage Turbine

1990 ◽  
Vol 112 (3) ◽  
pp. 370-376 ◽  
Author(s):  
J. J. Adamczyk ◽  
M. L. Celestina ◽  
T. A. Beach ◽  
M. Barnett
Keyword(s):  
Aspect Ratio ◽  
Flow Field ◽  
Three Dimensional ◽  
Equation System ◽  
Aerodynamic Performance ◽  
Experimental Measurements ◽  
Low Aspect Ratio ◽  
Blade Row ◽  
Multistage Turbine ◽  
Secondary Flow Field

This work outlines a procedure for simulating the flow field within multistage turbomachinery, which includes the effects of unsteadiness, compressibility, and viscosity. The associated modeling equations are the average passage equation system, which governs the time-averaged flow field within a typical passage of a blade row embedded within a multistage configuration. The results from a simulation of a low aspect ratio stage and one-half turbine will be presented and compared with experimental measurements. It will be shown that the secondary flow field generated by the rotor causes the aerodynamic performance of the downstream vane to be significantly different from that of an isolated blade row.

scholarly journals Tandem-wing interactions on aerodynamic performance inspired by dragonfly hovering

2021 ◽  
Vol 8 (8) ◽  
pp. 202275
Author(s):  
Liansong Peng ◽  
Mengzong Zheng ◽  
Tianyu Pan ◽  
Guanting Su ◽  
Qiushi Li
Keyword(s):  
Body Weight ◽  
Flow Field ◽  
Numerical Simulations ◽  
Phase Difference ◽  
High Efficiency ◽  
Lift Coefficient ◽  
Aerodynamic Performance ◽  
The Body ◽  
Wing Surface ◽  
Phase Differences

Dragonflies possess two pairs of wings and the interactions between forewing (FW) and hindwing (HW) play an important role in dragonfly flight. The effects of tandem-wing (TW) interactions on the aerodynamic performance of dragonfly hovering have been investigated. Numerical simulations of single-wing hovering without interactions and TW hovering with interactions are conducted and compared. It is found that the TW interactions reduce the lift coefficient of FW and HW by 7.36% and 20.25% and also decrease the aerodynamic power and efficiency. The above effects are mainly caused by the interaction between the vortex structures of the FW and the HW, which makes the pressure of the wing surface and the flow field near the wings change. During the observations of dragonfly flight, it is found that the phase difference ( γ ) is not fixed. To explore the influence of phase difference on aerodynamic performance, TW hovering with different phase differences is studied. The results show that at γ = 22.5°, dragonflies produce the maximum lift which is more than 20% of the body weight with high efficiency; at γ = 180°, dragonflies generate the same lift as the body weight.

scholarly journals CFD Simulation Study on the Performance of a Modified Ram Air Turbine (RAT) for Power Generation in Aircrafts

Fluids ◽  
2021 ◽  
Vol 6 (11) ◽  
pp. 391
Author(s):  
Magedi Moh M. Saad ◽  
Sofian Mohd ◽  
Mohd Fadhli Zulkafli ◽  
Nor Afzanizam Samiran ◽  
Djamal Hissein Didane
Keyword(s):  
Fossil Fuels ◽  
Cfd Simulation ◽  
Turbulence Modeling ◽  
3D Models ◽  
Navier Stokes ◽  
Axial Distance ◽  
Navier Stokes Equation ◽  
Auxiliary Power Unit ◽  
Auxiliary Power ◽  
Air Turbine

The present paper aims to study the possibility of dispensing an auxiliary power unit (APU) in an aircraft powered by fossil fuels to reduce air pollution. It particularly seeks to evaluate the amount of power generated by the ram air turbine (RAT) using the novel counter-rotating technique while characterizing its optimum axial distance. The ram air turbine (RAT), which is already equipped in aircrafts, was enhanced to generate the amount of energy produced by the APU. The approach was implemented by a CRRAT system. Six airfoil profiles were tested based on 2D models and the best airfoil was chosen for implantation on the RAT and CRRAT systems. The performance of the conventional single-rotor RAT and CRRAT were analyzed using FLUENT software based on 3D models. The adopted numerical scheme was the Navier–Stokes equation with k–ω SST turbulence modeling. The dynamic mesh and user-defined function (UDF) were used to revolve the rotor turbine via wind. The results indicated that the FX63-137 airfoil profile showed a higher performance in terms of the lift-to-drag ratio compared to the other airfoils. The optimum axial distance between the two rotors was 0.087 m of the rotor diameter and the efficiency of the new CRRAT increased to almost 45% compared to the single-rotor RAT.

Numerical Simulations of Wind Effects on an Array of Ground Mounted Solar Panels

2014 ◽  
Author(s):  
Chowdhury Jubayer ◽  
Horia Hangan
Keyword(s):  
Boundary Layer ◽  
Flow Field ◽  
Numerical Simulations ◽  
Solar Panel ◽  
Navier Stokes ◽  
Wind Flow ◽  
Solar Panels ◽  
Array Configuration ◽  
Piv Measurement ◽  
Overturning Moment

In this study, numerical simulations using unsteady Reynolds-Averaged Navier-Stokes (RANS) approach with Shear Stress Transport (SST) k-ω turbulence closure are employed to investigate the wind loads and wind flow field of a ground mounted solar panel array. Atmospheric boundary layer wind profiles for open terrain roughness with Reynolds number of 2.2×106, based on the wind speed at the lower edge and the chord length of a stand-alone system, are employed. Four different wind directions (0°, 45°, 135° and 180°) are considered. The numerical modeling approach employed in this study is validated for a stand-alone solar panel system by comparing the surface pressures with the study by [1] and the velocity field with a Particle Image Velocimetry (PIV) measurement carried out in the Boundary Layer Wind Tunnel I at the Western University, Canada. Analyzing the wind flow field for the array configuration shows that for 0° and 180° wind directions, all trailing rows are in the complete wake of the first windward row. It is also shown that in terms of maximum drag and lift, 0° and 180° wind directions are the critical wind directions with the first windward row being the critical row. On the other hand, in terms of overturning moment, 45° and 135° are the critical wind directions, with similar overturning moment coefficients for each row.

Optimized Shroud Design for Axial Turbine Aerodynamic Performance

2008 ◽  
Vol 130 (3) ◽  
Author(s):  
L. Porreca ◽  
A. I. Kalfas ◽  
R. S. Abhari
Keyword(s):  
Flow Field ◽  
Three Dimensional ◽  
Aerodynamic Performance ◽  
Field Analysis ◽  
Test Cases ◽  
Axial Turbine ◽  
Significant Difference ◽  
Flow Field Analysis ◽  
The Impact ◽  
Partial Shroud

This paper presents a comprehensive study of the effect of shroud design in axial turbine aerodynamics. Experimental measurements and numerical simulations have been conducted on three different test cases with identical blade geometry and tip clearances but different shroud designs. The first and second test cases are representative of a full shroud and a nonaxisymmetric partial shroud geometry while the third test case uses an optimized partial shroud. Partial shrouds are sometimes used in industrial application in order to benefit from the advantage of shrouded configuration, as well as reduce mechanical stress on the blades. However, the optimal compromise between mechanical considerations and aerodynamic performances is still an open issue due to the resulting highly three-dimensional unsteady flow field. Aerodynamic performance is measured in a low-speed axial turbine facility and shows that there are clear differences between the test cases. In addition, steady and time resolved measurements are performed together with computational analysis in order to improve the understanding of the effect of the shroud geometry on the flow field and to quantify the sources of the resultant additional losses. The flow field analysis shows that the effect of the shroud geometry is significant from 60% blade height span to the tip. Tip leakage vortex in the first rotor is originated in the partial shroud test cases while the full shroud case presents only a weak indigenous tip passage vortex. This results in a significant difference in the secondary flow development in the following second stator with associated losses that varies by about 1% in this row. The analysis shows that the modified partial shroud design has improved considerably the aerodynamic efficiency by about 0.6% by keeping almost unchanged the overall weight of this component, and thus blade root stresses. The work, therefore, presents a comprehensive flow field analysis and shows the impact of the shroud geometry in the aerodynamic performance.

Numerical Simulation on Aerodynamic Performance of Ram Air Turbine Based on Mixed Flow Field

2018 ◽  
Author(s):  
Xiangbo Zhang ◽  
Shuiting Ding ◽  
Farong Du ◽  
Fenzhu Ji ◽  
Shengrong Guo
Keyword(s):  
Flow Field ◽  
Pitch Angle ◽  
Aerodynamic Performance ◽  
Power Coefficient ◽  
Blade Surface ◽  
Mixed Flow ◽  
Navier Stokes Equation ◽  
Operation Conditions ◽  
Air Turbine ◽  
Turbine Speed

Ram air turbine (RAT) is an emergency power source to supply power in case of the main engine and auxiliary engine lost power. Which can extract energy from airflow through rotating turbine. So it is important to investigate turbine aerodynamic performances. According to some type of RAT, we established a numerical model based on Navier–Stokes equation in rotating frames of reference. Calculation domain is divided into three fluid domains. All three regions are linked in the form of interface. Aerodynamic performance of RAT is simulated with computational fluid dynamics (CFD) soft. The extracted power and rotor power coefficient are analyzed under different running conditions. Next, we also investigate RAT aerodynamic performance at different pitch angle and turbine speed. The pressure and velocity distribution on the blade surface are studied. Besides, the method of multiple rotation frame (MRF) is used to simulate mixed flow field of the RAT which pitch angle is adjustable. The simulation results show that: turbine output power and rotor power coefficient can meet the needs of aircraft by adjusting the pitch angle under various operation conditions. The optimal operating point could be obtained by calculating RAT aerodynamic performance. The distribution of blade surface pressure and velocity could provide an important reference for the optimization of turbine blade designing. MRF can be used to calculate turbine aerodynamic performance.

The Aerodynamic Performance of a Freely Hinged Door between Two Flows

1978 ◽  
Vol 29 (3) ◽  
pp. 144-160
Author(s):  
B.L. Hunt ◽  
S.A. Bizon ◽  
S.A. Taylor ◽  
D.A. Wilson
Keyword(s):  
Mass Flow ◽  
Pressure Difference ◽  
Velocity Ratio ◽  
Relative Magnitude ◽  
Aerodynamic Performance ◽  
Considerable Influence ◽  
Flow Ratio ◽  
Aerodynamic Parameters ◽  
Different Shapes ◽  
Mass Flow Ratio

SummaryThis paper reports experimental results for the performance of a freely hinged door between two incompressible air flows of different total pressures and different velocities. The apparatus used is a laboratory idealisation of the tertiary door system for an aircraft propulsion nozzle. The governing parameters are identified and the performance is presented in terms of the equilibrium door angle and the relative magnitude of the mass flow admitted. Three doors of different shapes were used and results are also presented for a plain opening. The main aerodynamic parameters are shown to be the velocity ratio and a non-dimensional pressure difference across the door. The shape of the downstream door jamb is found to have a considerable influence on the operation of the door at low angles. Removal of the door results in a lower entry mass flow over most of the operating range. It is shown that the mass flow ratio can be predicted quite well from the measured door angles by means of a simple theory.

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