scholarly journals Development of High-Fidelity Numerical Methodology Based on Wavenumber-Frequency Transform for Quantifying Internal Aerodynamic Noise in Critical Nozzle

2019 ◽  
Vol 9 (14) ◽  
pp. 2885
Author(s):  
Garam Ku ◽  
Songjune Lee ◽  
Cheolung Cheong ◽  
Woong Kang ◽  
Kuksu Kim
Keyword(s):  
Surface Pressure ◽  
Numerical Procedure ◽  
Acoustic Power ◽  
High Accuracy ◽  
Piping System ◽  
High Fidelity ◽  
Pressure Relief ◽  
Critical Nozzle ◽  
Eddy Simulation ◽  
Large Eddy

In industrial fields dealing with high-temperature and high-pressure gas such as chemical, petrochemical, and offshore oil production plants, piping systems with valves are frequently used to protect the relevant system and equipment from being damaged by such gases. However, excessive noise is sometimes generated by the valve flow in the piping system, causing so-called acoustic induced vibration in the pipe wall. Therefore, it is of great importance to design the related system to avoid this phenomenon. In this study, a high-fidelity numerical procedure is proposed to assess the acoustic power generated by pressure relief devices in a pipe. The method consists of three sequential steps: high accuracy large eddy simulation, wavenumber-frequency transform, and duct acoustic theory. The critical nozzle is selected as a target system since it is commonly used as a flowmeter and thus there are a lot of relevant data for comparison. First, the steady Reynold-Averaged Navier–Stokes (RANS) solver is used to predict the flow rate of the two-dimensional axisymmetric critical nozzles, and its validity is confirmed by comparing the predicted results with the measured ones. There is good agreement between the two results. Then, a high accuracy Large Eddy Simulation (LES) technique is performed on the three-dimensional critical nozzle, and the steady-state RANS result is used as the initial condition to accelerate the convergence of the unsteady simulation. The validity of the unsteady LES results is also confirmed by comparing them with measured surface pressure data. The wavenumber-frequency transform is taken on the LES results, and the compressible surface pressure components matching the acoustical duct modes are identified in the wavenumber-frequency pressure diagram. The inverse wavenumber-frequency transform taken on the compressible pressure components leads to the acoustic power spectrum. These results reveal that the current numerical procedure can be used to more accurately predict the acoustic power generated by pressure relief device in the piping system.

scholarly journals Numerical study of a control scheme on flow-induced cavity noise

2019 ◽  
Vol 283 ◽  
pp. 09002
Author(s):  
Lulu Liu ◽  
Jin Liu ◽  
Shijin Lyu
Keyword(s):  
Experimental Data ◽  
Cavity Length ◽  
Numerical Study ◽  
Numerical Procedure ◽  
Acoustic Analogy ◽  
Cavity Depth ◽  
Eddy Simulation ◽  
Control Scheme ◽  
Large Eddy ◽  
Flow Induced Noise

A numerical procedure for flow induced cavity noise is established in the paper. The procedure is based on large eddy simulation and FW-H acoustic analogy. The computational scheme is validated by comparing with experimental data. The change of flow induced noise along with cavity length, cavity depth and velocity is studied. A noise control scheme, which includes upright grille and oblique grille, is designed for reducing the flow-induced cavity noise. It turns out that the oblique grille shows superiority in the reduction of cavity noise by modifying the flow structure of the sheat layer.

scholarly journals Towards Massively Parallel Large Eddy Simulation of Turbine Stages

2013 ◽  
Author(s):  
Gaofeng Wang ◽  
Dimitrios Papadogiannis ◽  
Florent Duchaine ◽  
Nicolas Gourdain ◽  
Laurent Y. M. Gicquel
Keyword(s):  
Experimental Data ◽  
Large Eddy Simulation ◽  
Gas Turbine ◽  
High Performance ◽  
Fluid Dynamic ◽  
Rotor Blades ◽  
Massively Parallel ◽  
High Fidelity ◽  
Eddy Simulation ◽  
Large Eddy

The context of integrated numerical simulations of gas turbine engines by use of high-fidelity Computational Fluid Dynamic (CFD) tools recently emerged as a promising path to improve engines design and understanding. Relying on massively parallel super-computing such propositions still have to prove feasibility to efficiently take advantage of the ever increasing computing power made available worldwide. Although Large Eddy Simulation (LES) has recently proven its superiority in the context of the combustion chamber of gas turbine, methodologies need to be developed and start addressing the problem of the turbomachinery stages, if integrated simulations based on LES are to be foreseen. In the proposed work an in-house code and strategy, called TurboAVBP, is developed for turbomachinery LES thanks to the coupling of multi-copies of the unstructured compressible reacting LES solver AVBP, designed to run efficiently on high performance massively parallel architectures. Aside from the specificity of such wall bounded flows, rotor/stator LES type simulations require specific attention and the interface should not interfere with the numeric scheme to preserve proper representation of the unsteady physics crossing this interface. A tentative LES compliant solution based on moving overset grids method is proposed and evaluated in this work for high-fidelity simulation of the rotor/stator interactions. Simple test cases of increasing difficulty with reference numerical are detailed and prove the solution in handling acoustics, vortices and turbulence. The approach is then applied to the QinetiQ MT1 high-pressure transonic turbine for comparison with experimental data. Two configurations are computed: the first one is composed of 1 scaled stator section and 2 rotors while the second computation considers the geometrically accurate periodic quarter of the machine, i.e. 8 stators and 15 rotors to test scalability issues of such applications. Although under-resolved, the LES pressure profiles on the stator and rotor blades appear to be in good agreement with experimental data and are quite competitive compared to the traditional (Unsteady) Reynolds-Averaged Navier-Stokes (RANS or URANS) modeling approach. Unsteady features inherently present in these LES underline the complexity of the flow in a turbine stage and clearly demand additional diagnostics to be properly validated.

scholarly journals Unsteady Adjoint of Pressure Loss for a Fundamental Transonic Turbine Vane

2016 ◽  
Vol 139 (3) ◽  
Author(s):  
Chaitanya Talnikar ◽  
Qiqi Wang ◽  
Gregory M. Laskowski
Keyword(s):  
Boundary Layer ◽  
Large Eddy Simulation ◽  
Adjoint Equations ◽  
High Fidelity ◽  
Trailing Edge ◽  
Eddy Simulation ◽  
Large Eddy ◽  
High Fidelity Simulations ◽  
Unsteady Adjoint ◽  
Adjoint Solutions

High-fidelity simulations, e.g., large eddy simulation (LES), are often needed for accurately predicting pressure losses due to wake mixing and boundary layer development in turbomachinery applications. An unsteady adjoint of high-fidelity simulations is useful for design optimization in such aerodynamic applications. In this paper, we present unsteady adjoint solutions using a large eddy simulation model for an inlet guide vane from von Karman Institute (VKI) using aerothermal objectives. The unsteady adjoint method is effective in capturing the gradient for a short time interval aerothermal objective, whereas the method provides diverging gradients for long time-averaged thermal objectives. As the boundary layer on the suction side near the trailing edge of the vane is turbulent, it poses a challenge for the adjoint solver. The chaotic dynamics cause the adjoint solution to diverge exponentially from the trailing edge region when solved backward in time. This results in the corruption of the sensitivities obtained from the adjoint solutions. An energy analysis of the unsteady compressible Navier–Stokes adjoint equations indicates that adding artificial viscosity to the adjoint equations can dissipate the adjoint energy while potentially maintaining the accuracy of the adjoint sensitivities. Analyzing the growth term of the adjoint energy provides a metric for identifying the regions in the flow where the adjoint term is diverging. Results for the vane obtained from simulations performed on the Titan supercomputer are demonstrated.

scholarly journals Numerical Investigation of Injection, Mixing and Combustion in Rocket Engines Under High-Pressure Conditions

2020 ◽  
pp. 209-221
Author(s):  
Christoph Traxinger ◽  
Julian Zips ◽  
Christian Stemmer ◽  
Michael Pfitzner
Keyword(s):  
High Pressure ◽  
Large Eddy Simulations ◽  
Experimental Investigations ◽  
High Fidelity ◽  
Rocket Engines ◽  
Eddy Simulation ◽  
Liquid Rocket Engines ◽  
Large Eddy ◽  
Numerical Tools ◽  
Liquid Rocket

Abstract The design and development of future rocket engines severely relies on accurate, efficient and robust numerical tools. Large-Eddy Simulation in combination with high-fidelity thermodynamics and combustion models is a promising candidate for the accurate prediction of the flow field and the investigation and understanding of the on-going processes during mixing and combustion. In the present work, a numerical framework is presented capable of predicting real-gas behavior and nonadiabatic combustion under conditions typically encountered in liquid rocket engines. Results of Large-Eddy Simulations are compared to experimental investigations. Overall, a good agreement is found making the introduced numerical tool suitable for the high-fidelity investigation of high-pressure mixing and combustion.

Noise Prediction of Pressure-Mismatched Jets Using Unstructured Large Eddy Simulation

2011 ◽  
Author(s):  
Yaser Khalighi ◽  
Frank Ham ◽  
Parviz Moin ◽  
Sanjiva K. Lele ◽  
Robert H. Schlinker
Keyword(s):  
Large Eddy Simulation ◽  
Turbulent Flow ◽  
Three Dimensional ◽  
Empirical Models ◽  
Nozzle Geometry ◽  
High Fidelity ◽  
Noise Generation ◽  
Eddy Simulation ◽  
Large Eddy ◽  
Generation Mechanisms

It is our premise that significant new advances in the understanding of noise generation mechanisms for jets and realistic methods for reducing this noise can be developed by exploiting high-fidelity computational fluid dynamics: namely large eddy simulation (LES). In LES, the important energy-containing structures in the flow are resolved explicitly, resulting in a time-dependent, three-dimensional realization of the turbulent flow. In the context of LES, the unsteady flow occurring in the jet plume (and its associated sound) can be accurately predicted without resort to adjustable empirical models. In such a framework, the nozzle geometry can be included to directly influence the turbulent flow including its coherent and fine-scale motions. The effects of propulsion system design choices and issues of integration with the airframe can also be logically addressed.

Numerical Simulations of Thermal-Mixing in T-Junction Piping System Using Large Eddy Simulation Approach

2011 ◽  
Author(s):  
Masaaki Tanaka ◽  
Satoshi Murakami ◽  
Yasuhiro Miyake ◽  
Hiroyuki Ohshima
Keyword(s):  
Numerical Simulations ◽  
Large Scale ◽  
Branch Pipe ◽  
Three Dimensional ◽  
Piping System ◽  
Thermal Mixing ◽  
Eddy Simulation ◽  
Large Eddy ◽  
Thermal Striping ◽  
High Cycle Thermal Fatigue

Thermal striping phenomenon caused by mixing of fluids at different temperatures is one of the most important issues in design of fast breeder reactors (FBRs), because it may cause high-cycle thermal fatigue in structure. Authors have been developed a numerical simulation code MUGTHES to investigate thermal striping phenomena in FBRs and to give transient data of temperature in the fluid and the structure for an evaluation method of the high-cycle thermal fatigue problem. MUGTHES employs the boundary fitted coordinate (BFC) system and deals with three-dimensional transient thermal-hydraulic problems by using the large eddy simulation (LES) approach and artificial wall conditions derived by a wall function law. In this paper, numerical simulations of MUGTHES in T-junction piping system appear. Boundary conditions for the simulations are chosen from an existing water experiment in JAEA, named as WATLON experiment. The wall jet condition in which the branch pipe jet flows away touching main pipe wall on the branch pipe side and the impinging jet condition in which the branch pipe jet impinges on the wall surface on the opposite side of the branch pipe are selected, because significant temperature fluctuation may be induced on the wall surfaces by the branch pipe jet behavior. Numerical results by MUGTHES are validated by comparisons with measured velocity and temperature profiles. Three dimensional large-scale eddies are identified behind of the branch pipe jet in the wall jet case and in front of the branch pipe jet in the impinging jet case, respectively. Through these numerical simulations in the T-pipe, generation mechanism of temperature fluctuation in thermal mixing process is revealed in the relation with the large-scale eddy motion.

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