scholarly journals NUMERICAL INVESTIGATION OF A TONE NOISE OF THE FAN WITH CASING TREATMENT

2021 ◽  
pp. 24-38
Author(s):  
Yaroslav Druzhinin ◽  
◽  
Viktor Mileshin ◽  
Anton Rossikhin ◽  
◽  
...  
Keyword(s):  
Flow Field ◽  
Unsteady Flow ◽  
Numerical Investigation ◽  
Significant Influence ◽  
Aerodynamic Characteristics ◽  
Operational Conditions ◽  
Casing Treatment ◽  
Harmonic Method ◽  
Surge Line ◽  
Bypass Ratio

Numerical investigation of influence of a slot-type casing treatment on acoustic and aerodynamic characteristics of the fan of ultra-high bypass ratio turbofan is presented. The investigation was performed using NUMECA FINE/Turbo solver. NLH harmonic method was used to simulate the effect of casing treatment on unsteady flow field in the turbomachine. Two operational conditions were investigated – “sideline” and “approach”. The attention for the first operational condition was paid for aerodynamic characteristics. Significant influence of casing treatment on them was found especially near the surge line. At the “approach” operational conditions the attention was paid for the proper calculation of tone noise. It was shown that the installation of casing treatment leads to decrease of power of tone noise radiated through the inlet. However the power of the tone noise, radiated through the nozzle, and also the overall power of tone noise increase.

Experimental Investigation of the Steady and Unsteady Flow Field in a Single Stage Low Pressure Axial Compressor With a Circumferential Groove Casing Treatment

2010 ◽  
Author(s):  
N. Van de Wyer ◽  
B. Farkas ◽  
J. Desset ◽  
J. F. Brouckaert ◽  
J.-F. Thomas ◽  
...  
Keyword(s):  
Experimental Investigation ◽  
Flow Field ◽  
Unsteady Flow ◽  
Axial Compressor ◽  
Low Pressure ◽  
Fast Response ◽  
Single Stage ◽  
Compressor Stage ◽  
Casing Treatment ◽  
Circumferential Groove

This paper deals with the experimental investigation of the influence of a circumferential groove casing treatment on the performance and stability margin of a single stage low pressure axial compressor. The design of the compressor stage is representative of a booster stage for the new counter-rotating turbofan engine architecture and is characterized by unusually high loading and flow coefficients. The choice of the circumferential groove is described on the basis of a numerical parametric study on the number of grooves, the axial position, the depth and width of the groove. The experiments were performed at a Reynolds number corresponding to cruise conditions in the von Karman Institute closed loop high speed compressor test rig R4. The detailed performance characterization of the compressor stage with casing treatment was mapped at four operating points from choke to stall at design speed. The compressor stall limit was determined at several other off-design speeds. Detailed steady and unsteady measurements were performed to determine the flow field characteristics of the rotor and of the complete stage. Conventional pressure, temperature and directional probes were used along with fast response pressure sensors in the rotor casing and in the groove. Simultaneous traverses with a fast response total pressure probe were used to map the unsteady flow field at the rotor exit allowing an experimental capture of the tip leakage vortex path and extension through the rotor passage. A comparison of the flow features with and without casing treatment was performed and the results are discussed against 3D viscous computational predictions. The casing treatment did not present any improvement of the compressor stall margin but no significant performance degradation was observed either. The CFD predictions showed a good agreement with the measurements and their analysis supported the experimental results.

Analysis of the Unsteady Flow in an Aspirated Counter-Rotating Compressor Using the Nonlinear Harmonic Method

2009 ◽  
Author(s):  
Emanuele Guidotti ◽  
Mark G. Turner
Keyword(s):  
Flow Field ◽  
Unsteady Flow ◽  
Frequency Domain ◽  
Navier Stokes ◽  
Test Case ◽  
Numerical Accuracy ◽  
Flow Solver ◽  
Harmonic Method ◽  
Flow Change ◽  
Inlet Boundary Condition

A multistage frequency domain (Nonlinear Harmonic) Navier-Stokes unsteady flow solver has been used to analyze the flow field in the MIT (rotor/rotor) aspirated counter-rotating compressor. The numerical accuracy and computational efficiency of the Nonlinear Harmonic method implemented in Numeca’s Fine/Turbo CFD code has been demonstrated by comparing predictions with experimental data and nonlinear time-accurate solutions for the test case. The comparison is good, especially considering the big savings in time with respect to a time accurate simulation. An imposed inlet boundary condition takes into account the flow change due to the IGV (not simulated in the computational model). Details of the flow field are presented and physical explanations are provided. Also, suggestions and recommendations on the use of the Nonlinear Harmonic method are provided. From this work it can be concluded that the development of efficient frequency domain approaches enables routine unsteady flow predictions to be used in the design of modern turbomachinery.

Unsteady Interactions Between Axial Turbine and Nonaxisymmetric Exhaust Hood Under Different Operational Conditions

2011 ◽  
Vol 134 (4) ◽  
Author(s):  
Jing-Lun Fu ◽  
Jian-Jun Liu ◽  
Si-Jing Zhou
Keyword(s):  
Flow Field ◽  
Unsteady Flow ◽  
Rotor Blade ◽  
Exhaust System ◽  
Single Stage ◽  
Exhaust Hood ◽  
Turbine Stage ◽  
Axial Turbine ◽  
Operational Conditions ◽  
Flow Interactions

The exhaust system in condensing steam turbines is used to recover leaving kinetic energy of the last stage turbine, while guiding the flow from turbine to condenser. The flows in the exhaust system and the turbine stage are fully coupled and inherently unsteady. The unsteady flow interactions between the turbine and the exhaust system have a strong impact on the blade loading or blade aerodynamic force. This paper describes the unsteady flow interactions between a single-stage axial turbine and an exhaust system. The experimental and numerical studies on the coupled flow field in the single-stage turbine and the exhaust hood model under different operational conditions have been carried out. Unsteady pressure at the turbine rotor blade, turbine outlet, and exhaust outcasing are measured and compared with the numerical prediction. The details of unsteady flow in the exhaust system with the whole annulus stator and rotor blade rows are simulated by employing the computational fluid dynamics software CFX-5. Results show that for the investigated turbine-exhaust configuration the influence of the flow field in the exhaust system on the unsteady blade force is much stronger than that of the stator and rotor interaction. The flow pattern in the exhaust system changes with the turbine operational condition, which influences the unsteady flow in the turbine stage further.

An Experimental and Numerical Investigation of the Aerodynamic Characteristics of a Flameless Combustor

2019 ◽  
Author(s):  
M. P. Huijts ◽  
A. A. V. Perpignan ◽  
A. G. Rao
Keyword(s):  
Flow Field ◽  
Numerical Investigation ◽  
Flow Structure ◽  
Gas Turbines ◽  
Turbulence Models ◽  
Fuel Mixture ◽  
Aerodynamic Characteristics ◽  
Navier Stokes ◽  
Chamber Length ◽  
Image Velocimetry

Abstract The flameless combustion (FC) regime is a promising technology for gas turbines, as it potentially yields lower NOx emissions while maintaining high combustion efficiencies. However, the application of FC to gas turbines is still challenging as required conditions for its occurrence depend on several factors such as reactants mixing, residence times, heat losses, and chemical time-scales. Since the mixing of the reactants and incoming fresh air-fuel mixture plays an important role in FC, the aerodynamic characteristics of the combustor are instrumental in determining the combustor emission performance. Focusing on the aerodynamic characteristics, this paper is dedicated to the visualization and description of the flow inside a jet-based combustor designed to operate under FC. The cylindrical combustor has a FLOX® burner head with 12 concentrically placed nozzles, while an acrylic cylinder allowed full optical access to the flow field. The investigation was performed for non-reactive flow. Using Particle Image Velocimetry and a Reynolds-averaged Navier-Stokes CFD analysis, the flow was visualized and modelled. The simulations were run with the Standard and Realizable k-ε (SKE and RKE, respectively), as well as a Reynolds Stress turbulence model. The effect of modifying the SKE model C1ε constant was also investigated. In the experimental campaign, the influence of combustion chamber length, nozzle diameter, and jet velocity were investigated with respect to flow structure, recirculation ratios and entrainment behavior. The results show that the flow structure is mainly dependent on nozzle diameters, while the jet momentum is the correct parameter to assess the recirculation impact of a certain jet flow. The numerical investigation shows that the turbulence intensity at the boundaries is an important parameter to accurately simulate the jet spreading. None of the used turbulence models fully represented the flow field. Nonetheless, the SKE model with model C1ε = 1.44 was the best at representing the jets penetration and vortex core positions, and the recirculation ratio values predicted by it were in good agreement.

Numerical Investigation of a Lean Premixed Swirl-Stabilized Hydrogen Combustor and Operational Conditions Close to Flashback

2018 ◽  
Author(s):  
D. Mira ◽  
O. Lehmkuhl ◽  
P. Stathopoulos ◽  
T. Tanneberger ◽  
T. G. Reichel ◽  
...  
Keyword(s):  
Flow Field ◽  
Numerical Investigation ◽  
Operating Conditions ◽  
Combustion Model ◽  
Reacting Flow ◽  
Operational Conditions ◽  
Air Jet ◽  
Large Eddy ◽  
Burner Design ◽  
The Eu

The current study presents a numerical investigation of the flow field of a swirl-stabilized burner featuring a non-swirling axial air jet on the central axis of the mixing tube. The system has been designed and optimized to burn hydrogen at the Technische Universität Berlin over the last 6 years in the context of the EU-funded projects GREENEST and AHEAD. As the burner design was based on experimental work, high-fidelity large-eddy simulations (LES) are used to provide deeper understanding on the non-reacting and reacting flow fields to elucidate the occurrence of flashback under certain operating conditions. The experimental measurements suggest that flashback is produced by a velocity deficit at the mixing tube outlet and these conditions are analyzed here using LES. The work includes code validation for non-reacting and reacting conditions by comparison to water tunnel and combustion test rig data, and aims to evaluate the accuracy of LES with a combustion model based on premixed flamelets to predict the reacting flow field under conditions close to flashback.

Analysis of Stator-Stator Clocking in a Transonic Turbine

2007 ◽  
Author(s):  
N. Billiard ◽  
V. Jerez Fidalgo ◽  
R. De´nos ◽  
G. Paniagua
Keyword(s):  
Flow Field ◽  
Unsteady Flow ◽  
Numerical Investigation ◽  
Time Resolved ◽  
Relative Pitch ◽  
Shock System ◽  
Transonic Turbine ◽  
Mechanisms Of Migration

Clocking, i.e. the relative pitch-wise positioning between two successive vanes with the same amount of airfoils, has been demonstrated to bring potential aero-thermal benefits in several recent studies. Indeed, across a vane pitch, a variation of both time-averaged and time-resolved quantities is induced. In order to advance the knowledge on clocking, this 2D numerical investigation proposes a complete description of the unsteady flow field at midspan in a one and half stage turbine at four clocking positions. Mechanisms of migration across the rotor of the first vane wake and its interaction with the second vane has been put into evidence. Additionally, the behavior of the shock system between the rotor and the second stator is assessed indicating effects due to the clocking, like the similar the shape of the shock system when rotor/2nd stator are in the same relative positions.

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