Validation setup for the investigation of aeroacoustic and vibroacoustic sound emission of confined turbulent flows

2021 ◽  
Vol 263 (6) ◽  
pp. 519-525
Author(s):  
Paul Maurerlehner ◽  
Stefan Schoder ◽  
Sebastian Floss ◽  
Johannes Tieber ◽  
Helfried Steiner ◽  
...  
Keyword(s):  
Turbulent Flows ◽  
Hybrid Approach ◽  
Internal Flow ◽  
Combustion Noise ◽  
Inlet Section ◽  
Flow Conditions ◽  
System A ◽  
Validation Procedure ◽  
Measurement Object ◽  
Confined Flows

Confined flows induce sound at certain flow conditions, which can be annoying in electric vehicles due to the absence of combustion noise. Noise in internal flow may occur due to unfavorable flow-guiding geometries caused by the complex packaging required in engine compartments of modern vehicles. The flow-induced sound is emitted at duct openings (e.g., ventilation inside the passenger cabin). It also originates from the vibroacoustic emissions of the flow-guiding structure excited by the flow. We propose a modular validation procedure for aeroacoustic simulations of confined flows. The experimental setup includes the vibroacoustic emission of the involved flow-guiding structure. The test rig consists of a sensor system, a high-pressure blower, modular pipe sections, and absorbers, which decouple the system from blower noise and avoid acoustic reflections at the pipe exit. A sufficiently long straight inlet section ensures fully developed flow conditions entering the investigated region. For capturing the vibroacoustic sound radiation of the flow-guiding structure, the measurement object and the surrounding microphones are encapsulated in a wooden box, lined with micro-perforated plates. Measurement results of a straight pipe and a pipe with a half-moon-shaped orifice are presented. Additionally, the sound generation is reproduced by Lighthill's aeroacoustic analogy applying a hybrid approach.

Improvement of Stalling Characteristics of an Axial-Flow Fan by Radial-Vaned Air-Separators

2010 ◽  
Vol 132 (2) ◽  
Author(s):  
Nobuyuki Yamaguchi ◽  
Masayuki Ogata ◽  
Yohei Kato
Keyword(s):  
Solid Wall ◽  
Axial Flow ◽  
Internal Flow ◽  
Rotor Blades ◽  
Relative Location ◽  
Flow Conditions ◽  
Axial Flow Fan ◽  
Light Load ◽  
Stall Prevention ◽  
Air Separator

An improved construction of air-separator device, which has radial-vanes embedded within its inlet circumferential opening with their leading-edges facing the moving tips of the fan rotor-blades so as to scoop the tip flow, was investigated with respect to the stall-prevention effect on a low-speed, single-stage, lightly loaded, axial-flow fan. Stall-prevention effects by the separator layout, relative location of the separator to the rotor-blades, and widths of the openings of the air-separator inlet and exit were parametrically surveyed. As far as the particular fan is concerned, the device together with the best relative location has proved to be able to eliminate effectively the stall zone having existed in the original solid-wall characteristics, which has confirmed the promising potential of the device. Guidelines were obtained from the data for optimizing relative locations of the device to the rotor-blades, maximizing the stall-prevention effect of the device, and minimizing the axial size of the device for a required stall-prevention effect, at least for the particular fan and possibly for fans of similar light-load fans. The data suggest the changing internal flow conditions affected by the device conditions.

scholarly journals Design of Pressurized Metered Dose Inhalers Modeling of Internal Flow and Atomization

2010 ◽  
Vol 4 (2) ◽  
Author(s):  
Henk Versteeg ◽  
Abdul Qaiyum Shaik
Keyword(s):  
Experimental Work ◽  
Equilibrium Model ◽  
Lung Diseases ◽  
Internal Flow ◽  
Flow Conditions ◽  
Metered Dose Inhalers ◽  
Numerical Predictions ◽  
Metered Dose ◽  
Flow Through ◽  
Pressurized Metered Dose Inhalers

Pressurized metered-dose inhalers (pMDIs) have been the most effective therapeutic treatment for controlling lung diseases such as asthma and COPD. The flow through a two-orifice system of pMDI is very complex and poorly understood. Previous experimental work has shown that metastability may play a significant role in determining the flow conditions inside pMDIs. In this paper, we present the findings of a homogeneous equilibrium model with those of a delayed equilibrium model (DEM) accounting for propellant metastability. These results are compared with the available experimental and numerical predictions Further, the DEM was applied with HFA propellants R134A and R227, and the results were compared with traditional propellant R12.

Coupled and Uncoupled CFD Prediction of the Characteristics of Jets From Combustor Air Admission Ports

2000 ◽  
Author(s):  
J. J. McGuirk ◽  
A. Spencer
Keyword(s):  
Internal Flow ◽  
Flow Conditions ◽  
Empirical Correlations ◽  
Weakly Coupled ◽  
Primary Zone ◽  
Annular Combustor ◽  
Alternative Approaches ◽  
Jet Characteristics ◽  
Fully Coupled ◽  
Core Flows

The paper focusses attention on alternative approaches for treating the coupling between the flow in the annulus supply ducts and the jets which enter combustor primary and dilution zones through air admission ports. Traditionally CFD predictions of combustor flows have modeled this in a very weakly-coupled manner, with the port flow conditions being derived from 1D empirical correlations and used as boundary conditions for an internal-flow-only combustor CFD prediction. Recent work by the authors and others has introduced the viewpoint that fully-coupled external-annulus/internal-combustor predictions is the way forward. Experimental data is gathered in the present work to quantify the strength of the interaction between annulus and core flows, which ultimately determines the jet characteristics at port exit. These data are then used to illustrate the improvement in the prediction of port exit jet characteristics which is obtained by adopting fully-coupled calculations compared to the internal-flow-only approach. As a final demonstration of the importance of a fully coupled approach, isothermal calculations are presented for a single sector generic annular combustor. These show that quite different primary zone flow patterns are obtained from the two approaches, leading to considerable differences in the overall mixing pattern at combustor exit.

scholarly journals 1H NMR Metabolic Profile to Discriminate Pasture Based Alpine Asiago PDO Cheeses

Animals ◽  
2019 ◽  
Vol 9 (10) ◽  
pp. 722 ◽  
Author(s):  
Severino Segato ◽  
Augusta Caligiani ◽  
Barbara Contiero ◽  
Gianni Galaverna ◽  
Vittoria Bisutti ◽  
...  
Keyword(s):  
1H Nmr ◽  
Raw Milk ◽  
Water Soluble ◽  
Proton Nuclear Magnetic Resonance ◽  
Feeding System ◽  
System A ◽  
North Eastern ◽  
Dairy Plant ◽  
Validation Procedure ◽  
Upland Pasture

The study was carried out in an alpine area of North-Eastern Italy to assess the reliability of proton nuclear magnetic resonance 1H NMR to fingerprint and discriminate Asiago PDO cheeses processed in the same dairy plant from upland pasture-based milk or from upland hay-based milk. Six experimental types of Asiago cheese were made from raw milk considering 2 cows’ feeding systems (pasture- vs. hay-based milk) and 3 ripening times (2 months, Pressato vs. 4 months, Allevo_4 vs. 6 months, Allevo_6). Samples (n = 55) were submitted to chemical analysis and to 1H NMR coupled with multivariate canonical discriminant analysis. Choline, 2,3-butanediol, lysine, tyrosine, and some signals of sugar-like compounds were suggested as the main water-soluble metabolites useful to discriminate cheese according to cows’ feeding system. A wider pool of polar biomarkers explained the variation due to ripening time. The validation procedure based on a predictive set suggested that 1H NMR based metabolomics was an effective fingerprinting tool to identify pasture-based cheese samples with the shortest ripening period (Pressato). The classification to the actual feeding system of more aged cheese samples was less accurate likely due to their chemical and biochemical changes induced by a prolonged maturation process.

scholarly journals 1D-3D coupling investigation of hydraulic transient for power-supply failure of centrifugal pump-pipe system

2019 ◽  
Vol 21 (5) ◽  
pp. 708-726 ◽  
Author(s):  
Xiaoqin Li ◽  
Xuelin Tang ◽  
Min Zhu ◽  
Xiaoyan Shi
Keyword(s):  
Turbulent Flows ◽  
Flow Rate ◽  
Power Supply ◽  
Nuclear Power ◽  
Transient Flow ◽  
Internal Flow ◽  
Transition Process ◽  
Pipeline System ◽  
Pipe System ◽  
Rotating Speed

Abstract In the pumping station, the main feedwater system and the reactor system of nuclear power plant, power-supply failure causes strong hydraulic transients. One-dimensional method of characteristics (1D-MOC) is used to calculate the transient process in the pipeline system while three-dimensional (3D) computational fluid dynamics is employed to analyze the turbulent flows inside the pump and to obtain the performance parameters of the pump, and the data exchanges on the boundary conditions of the shared interface between 1D and 3D domains are updated based on the MpCCI platform. Based on the equation of motion of the pump motion parts, the relationship between the external characteristics and the internal flow field in the pump is further investigated because the dynamic behavior of the pump and the detailed fluid field evolutions inside the pump are captured during the transition process, and the transient flow rate, rotating speed, and pressure inside the impeller are comprehensively investigated. Meanwhile, compared with the data gained by experiment and traditional 1D-MOC, the relative errors of rotating speed and the flow rate obtained by 1D-3D coupling method are smaller than those by 1D-MOC. Furthermore, the influences of the main coupling parameters and coupling modes on the calculation results are analyzed, and the cause of the deviation is further explained.

Unsteady internal flow conditions of mini-centrifugal pump with splitter blades

2013 ◽  
Vol 22 (1) ◽  
pp. 86-91 ◽  
Author(s):  
T. Shigemitsu ◽  
J. Fukutomi ◽  
K. Kaji ◽  
T. Wada
Keyword(s):  
Centrifugal Pump ◽  
Internal Flow ◽  
Flow Conditions

LATTICE-BOLTZMANN SIMULATIONS OF FLOWS OVER BACKWARD-FACING INCLINED STEPS

2013 ◽  
Vol 25 (01) ◽  
pp. 1340021 ◽  
Author(s):  
RUPESH B. KOTAPATI ◽  
RICHARD SHOCK ◽  
HUDONG CHEN
Keyword(s):  
Turbulent Flows ◽  
Lattice Boltzmann ◽  
Turbulence Modeling ◽  
Laser Doppler Anemometry ◽  
Expansion Ratio ◽  
Outlet Section ◽  
Inlet Section ◽  
Eddy Simulation ◽  
Lattice Boltzmann Simulations ◽  
Inclination Angles

The lattice-Boltzmann method (LBM) is used in conjunction with a very large-eddy simulation (VLES) turbulence modeling approach to compute separated flows over backward-facing steps at different wall inclination angles. The Reynolds number Re H based on the step height H and center-line velocity at the channel inlet ucl is 64 000. The expansion ratio of the outlet section to the inlet section of the channel is 1.48. Wall inclination angles α considered include 10°, 15°, 20°, 25°, 30° and 90°. The computed flow fields for different inclination angles of the step are assessed against the laser Doppler anemometry (LDA) measurements of Makiola [B. Makiola, Ph.D. Thesis, University of Karlsruhe (1992); B. Ruck and B. Makiola, Flow separation over the step with inclined walls, in Near-Wall Turbulent Flows, eds. R. M. C. So, C. G. Speziale and B. E. Launder (Elsevier, 1993), p. 999.]. In addition to validating the lattice-Boltzmann solution with the experiments, this study also investigates the effects of three dimensionality, the proximity of the inlet to the step, and the grid resolution on the quality of the predictions.

Efficient Combustion Noise Simulation of a Gas Turbine Model Combustor Based on Stochastic Sound Sources

2015 ◽  
Author(s):  
Felix Grimm ◽  
Roland Ewert ◽  
Jürgen Dierke ◽  
Gilles Reichling ◽  
Berthold Noll ◽  
...  
Keyword(s):  
Gas Turbine ◽  
Sound Source ◽  
Sound Propagation ◽  
Hybrid Approach ◽  
Particle Method ◽  
Combustion Noise ◽  
Equation Modeling ◽  
Source Modeling ◽  
Sound Sources ◽  
Turbine Model

A gas turbine model combustor is simulated with a hybrid, stochastic and particle-based method for combustion noise prediction with full 3D sound source modeling and sound propagation. Alongside, an incompressible LES simulation of the burner is considered for the investigation of the performance of the hybrid approach. The highly efficient time-domain method consists of a stochastic sound source reconstruction algorithm, the Fast Random Particle Method (FRPM) and sound wave propagation via Linearized Euler Equations (LEEs). In the context of this work, the method is adapted and tested for Combustion Noise (CN) prediction. Monopole sound sources are reconstructed by using an estimation of turbulence statistics from reacting CFD-RANS simulations. First, steady state and unsteady CFD calculations of flow field and combustion of the model combustor are evaluated and compared to experimental results. Two equation modeling for turbulence and the EDM (Eddy Dissipation Model) with FRC (Finite Rate Chemistry) for combustion are employed. In a second step, the acoustics simulation setup for the model combustor is introduced. Selected results are presented and FRPM-CN pressure spectra are compared to experimental levels.

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