Influence of Hole-To-Hole Interaction On the Acoustic Behavior of Multi-Orifice Perforated Plates

2021 ◽  
Author(s):  
Alireza Javareshkian ◽  
Alexis Dancelme ◽  
Hongyu Chen ◽  
Thomas Sattelmayer
Keyword(s):  
Resonance Frequency ◽  
Interaction Effect ◽  
Gas Turbines ◽  
Acoustic Radiation ◽  
Three Dimensional ◽  
Perforated Plate ◽  
Optimized Design ◽  
Perforated Plates ◽  
Aero Engines ◽  
Hole Interaction

Abstract The acoustic liner's optimized design is critical for developing low-emission combustion systems in modern gas turbines and aero-engines. Several models are available in the literature for the acoustic impedance of perforated acoustic liners. Most of these models neglect the interaction effect between orifices. Generally, orifices are closely distributed such that the interactions between acoustic radiation from neighboring orifices can affect their acoustical behavior. The hole-to-hole interaction effect may change the resonator's resonance frequency due to the nonplanar wave creation in the vicinity of area jumps. Considering this effect may help to predict the resonator's resonance frequency accurately. In this work, a three-dimensional (3D) analytical approach is developed to consider the nonplanar wave creation in the cavity and orifices on the perforated plate. The proposed 3D analytical method is employed to determine the hole-to-hole interaction end-correction of multi-orifice perforated plates. The hole-to-hole interaction end-correction from a series of perforated plates with different orifice radii and spacings is obtained via the Finite Element Method (FEM). Perforated plates with different center-to-center hole spacing are tested using an impedance tube. Experimental results show a shift in the resonance frequency towards a lower frequency with decreasing holes' spacing. The comparison with the experiments shows that the available end-correction models in the literature cannot capture the hole-to-hole interaction effect observed in experiments. In contrast, the proposed model can reproduce measurements with high quality.

Influence of Hole-to-Hole Interaction on the Acoustic Behavior of Multi-Orifice Perforated Plates

2021 ◽  
Author(s):  
Alireza Javareshkian ◽  
Alexis Dancelme ◽  
Hongyu Chen ◽  
Thomas Sattelmayer
Keyword(s):  
Wave Propagation ◽  
Resonance Frequency ◽  
Interaction Effect ◽  
Gas Turbines ◽  
Perforated Plate ◽  
Wall Region ◽  
Optimized Design ◽  
Perforated Plates ◽  
Proposed Model ◽  
Hole Interaction

Abstract A key factor for developing low-emission combustion systems in modern gas turbines and aero-engines is the acoustic liner’s optimized design. Several models are available in the literature for the acoustic impedance of perforated acoustic liners. Most of these impedance models neglect the interaction effect between the orifices. In practice, the orifices are generally closely distributed such that the interactions between acoustic radiation from neighboring orifices can affect their acoustical behavior. The hole-to-hole interaction effect may change the resonance frequency of the resonator due to the nonplanar wave propagation in the cavity, the orifices in the perforated plate, and the near-wall region in the combustor. Considering this effect may help to predict the resonance frequency of the resonator accurately. In this work, a three-dimensional (3D) analytical approach is developed to account for the nonplanar wave propagation in the cavity and orifices on the perforated plate. The present study employs the proposed 3D analytical method to determine the hole-to-hole interaction end-correction of multi-orifice perforated plates. Additionally, the hole-to-hole interaction end-correction from a series of perforated plates with different orifice radii and spacings is obtained via the Finite Element Method (FEM). Perforated plate specimens with different center-to-center hole spacing are tested using an impedance tube. Experimental results show that the resonance frequency is shifted towards a lower frequency with decreasing holes’ spacing. The resulting model is compared with the experiments and the end-correction models available in the literature. The comparison shows that the available end-correction models cannot capture the hole-to-hole interaction effect, which is observed in experiments. In contrast, the proposed model can reproduce measurements with high quality. The resulting model demonstrates that the acoustic end-correction length for orifices is closely related to the perforated plate’s porosity ratio and orifice radius. The proposed model is readily applicable in the design of multi-orifice perforated plates.

scholarly journals THE STUDY OF ACOUSTIC CHARACTERISTICS OF THE PERFORATED AND HOMOGENOUS PLATES WITH SIMILAR GEOMETRICAL DIMENSIONS

Akustika ◽  
2019 ◽  
Vol 32 ◽  
pp. 79-82
Author(s):  
Valery Kirpichnikov ◽  
Lyudmila Drozdova ◽  
Alexei Koscheev ◽  
Ernst Myshinsky
Keyword(s):  
Resonant Frequency ◽  
Acoustic Radiation ◽  
Perforated Plate ◽  
Acoustic Characteristics ◽  
Resonant Frequencies ◽  
Perforated Plates ◽  
Resonance Frequencies ◽  
Flexural Vibrations ◽  
Geometrical Dimensions

The resonance frequencies of the flexural vibrations, input vibration excitability and acoustic radiation of the homogeneous and perforated plates were investigated. It is established that the average reduction range of the lower resonant frequency of flexural vibrations of the tested plates with the holes virtually coincides with the predictive estimate. The levels of the input vibration excitability of the perforated plate at the lower resonant frequencies exceeded the levels at the corresponding frequencies of the homogeneous plates greater than the calculated value. The levels of resonance acoustic radiation of the perforated plate were significantly less than of the homogeneous one.

Innovative Shallow Sump Customizations for Aero-Engine Bearing Chambers

2016 ◽  
Author(s):  
Budi Chandra ◽  
Kathy Simmons
Keyword(s):  
Air Flow ◽  
Three Dimensional ◽  
Perforated Plate ◽  
Test Facility ◽  
Stepped Spillway ◽  
Porous Insert ◽  
Excessive Heat ◽  
Wall Film ◽  
Aero Engines ◽  
And Function

Aero-engines incorporate various bearing chambers and these typically contain bearings, seals, rotating shafts, stationary walls and struts, and sometimes gears. Oil is supplied for lubrication and cooling and is removed (scavenged) from the sump region of the chamber (note that in some parts of the world the entire bearing chamber is referred to as the sump). Depending on the location and function of the bearing chamber, the sump region may be deep or shallow. Effective oil removal is essential as unnecessary working of the oil can lead to excessive heat generation and reduced overall efficiency. Therefore the design of the scavenge region in a bearing chamber, as well as the ability to assess its performance is very important. Previous work, much of which was conducted at the University of Nottingham Technology Centre in Gas Turbine Transmission Systems (UTC) suggests that oil often does not flow cleanly into the off-take due to a combination of several factors: oil momentum, windage, three-dimensional air flow that blocks the off-take flow or transports oil away from the off-take, and pooling because of separated air flow that acts on the oil once oil momentum is dissipated. Experimental research at the UTC found that scavenge performance is highly affected by the sump geometry, especially its depth. Variations of shallow sumps, although some are better than the others, cannot offer the same level of performance as a deep one. However space limitation in an engine often only allows for a shallow sump. This paper presents some experimental exploration on new design ideas. They are in the form of various inserts and attachments that were designed to improve scavenge performance of a shallow sump. These “custom” sumps were tested on the UTC’s scavenge test facility at various flow settings (wall film/flying droplets, liquid flow rates, scavenge ratios, shaft speeds). The residence volumes were measured and compared to a baseline configuration with reduction in residence volume desirable. The inserts tested were a Grille Cover, a Stepped Spillway, a Perforated Plate and a Porous Insert. Both the Porous Insert and the Perforated Plate showed reduced residence volumes in the demanding droplet/windage dominated flow condition with the Perforated Plate offering the best improvement over baseline.

An Experimental Verification of a New Design for Cantilevered Stators With Large Hub Clearances

2012 ◽  
Author(s):  
Martin Lange ◽  
Konrad Vogeler ◽  
Ronald Mailach ◽  
Sergio Elorza-Gomez
Keyword(s):  
Flow Field ◽  
Experimental Verification ◽  
Gas Turbines ◽  
Three Dimensional ◽  
Performance Data ◽  
Axial Compressors ◽  
The Third ◽  
Overall Performance ◽  
Overall Efficiency ◽  
Aero Engines

Proportionally large relative radial clearances can be found within the rear stages of multistage axial compressors of gas turbines and aero engines, with significant impact on their efficiency. A new three-dimensional design for cantilevered stators in axial compressors is presented, with the aim of improving the overall efficiency and losses of rear stage vanes with large relative hub clearances. The new vane design comprises an unconventional dihedral, with special consideration to reduce the losses caused by the hub clearance vortex. The design was tested in a 4-stage low speed axial research compressor under rear stage conditions. The results are compared to the nominal design to validate the reduction of hub clearance losses and blockage. For both designs, the hub clearances over the third and fourth stator were varied from 1.5% up to 6.0% of span. Overall performance data and flow field traverses upstream and downstream of stator 3 and rotor 4 will be presented in this article in comparison with 3D CFD results.

Numerical Investigation of Entropy Noise and Its Acoustic Sources in Aero-Engines

2008 ◽  
Author(s):  
Bernd Mu¨hlbauer ◽  
Berthold Noll ◽  
Manfred Aigner
Keyword(s):  
Numerical Investigation ◽  
Gas Turbines ◽  
Pressure Fluctuations ◽  
Three Dimensional ◽  
Power Spectra ◽  
Noise Simulation ◽  
Standard Configuration ◽  
Acoustic Sources ◽  
Aero Engines ◽  
First Time

In the present work, the generation and propagation of entropy noise was simulated applying a compressible three dimensional URANS CFD approach. To this end, a test rig, the so-called Entropy Wave Generator (EWG) was modeled. The EWG implies a non-reactive tube flow where entropy modes are induced to the air flow by a heating module. The generated temperature nonuniformities are accelerated in a convergent-divergent nozzle and excite entropy noise. Simulation results of pressure fluctuations and power spectra in the standard configuration as well as simulations of different operating points of the EWG are in very good agreement with measurements. Additionally, entropy noise was deduced for realistic gas turbine conditions with calculated sound pressure level above 160 dB, which evidences the relevance of entropy noise in gas turbines. The numerical investigation is completed by the analysis of the acoustic sources. For this purpose the acoustic sources caused by the acceleration of density inhomogeneities suggested by Dowling [1] were calculated. Thus, for the first time a method is introduced to locate the acoustic sources of entropy noise in the acceleration region.

Optimization of SCR inflow uniformity based on CFD simulation

Open Physics ◽  
2020 ◽  
Vol 18 (1) ◽  
pp. 1168-1177
Author(s):  
Ke Sun ◽  
Haiyang Zhao ◽  
Kui Zhao ◽  
Da Li ◽  
Shuzhan Bai
Keyword(s):  
Pressure Drop ◽  
Cfd Simulation ◽  
Catalytic Reduction ◽  
Perforated Plate ◽  
Optimized Design ◽  
Original Design ◽  
Perforated Plates ◽  
Scr Catalyst ◽  
Catalyst Carrier ◽  
The Cost

Abstract The inflow uniformity before selective catalytic reduction (SCR) catalyst carrier is a major issue for DeNO x capability of diesel engine after-treatment. Through the construction of the numerical model and CFD simulation of six perforated plate variations with different structural and positional characteristics, the influence of perforated plates on the uniformity of the airflow velocity at the inlet of the SCR catalyst carrier was analyzed. Comparison of different perforated plate variations shows that the encircling flow is a major hindrance to achieve higher inflow uniformity. Enclosed flow passage can remove the encircling flow and increase inflow uniformity at the cost of increased pressure drop. Rational layout of the perforated plate can achieve uniformity increase, while decrease pressure drop. High-velocity exhaust coupled with larger holes can improve both uniformity and pressure drop. The uniformity index increased from 97.6% of the original design to 98.7% of the optimized design, while pressure drop increased from 11.20 to 12.09 kPa. Weighing the relationship between inflow uniformity and pressure drop is an issue worthy of attention.

An Experimental Verification of a New Design for Cantilevered Stators With Large Hub Clearances

2013 ◽  
Vol 135 (4) ◽  
Author(s):  
Martin Lange ◽  
Konrad Vogeler ◽  
Ronald Mailach ◽  
Sergio Elorza Gomez
Keyword(s):  
Flow Field ◽  
Experimental Verification ◽  
Gas Turbines ◽  
Three Dimensional ◽  
Performance Data ◽  
Axial Compressors ◽  
The Third ◽  
Overall Performance ◽  
Overall Efficiency ◽  
Aero Engines

Proportionally large relative radial clearances can be found within the rear stages of multistage axial compressors of gas turbines and aero engines, with significant impact on their efficiency. A new three-dimensional design for cantilevered stators in axial compressors is presented, with the aim of improving the overall efficiency and losses of rear stage vanes with large relative hub clearances. The new vane design comprises an unconventional dihedral, with special consideration to reduce the losses caused by the hub clearance vortex. The design was tested in a 4-stage low speed axial research compressor under rear stage conditions. The results are compared to the nominal design to validate the reduction of hub clearance losses and blockage. For both designs, the hub clearances over the third and fourth stator were varied from 1.5% up to 6.0% of span. Overall performance data and flow field traverses upstream and downstream of stator 3 and rotor 4 will be presented in this article in comparison with 3D CFD results.

scholarly journals Influence of Holes Manufacture Technology on Perforated Plate Aerodynamics

Materials ◽  
2021 ◽  
Vol 14 (21) ◽  
pp. 6624
Author(s):  
Joanna Grzelak ◽  
Ryszard Szwaba
Keyword(s):  
Gas Turbines ◽  
Perforated Plate ◽  
Flow Characteristics ◽  
Aerodynamic Characteristics ◽  
Physical Models ◽  
Experimental Investigations ◽  
Perforated Plates ◽  
Flow Losses ◽  
Large Numbers

Transpiration flow is a very important and still open subject in many technical applications. Perforated walls are useful for the purpose of “flow control”, as well as for the cooling of walls and blades (effusive cooling) in gas turbines. We are still not able to include large numbers of holes in the numerical calculations and therefore we need physical models. Problems are related also to the quality of the holes in perforated plates. The present transpiration analysis concerns with experimental investigations of the air flow through perforated plates with microholes of 125 and 300 µm diameters. A good accordance of the results with other experiments, simulations and theory was obtained. The received results very clearly show that technology manufacturing of plate holes influences on their aerodynamic characteristics. It turned out that the quality of the plate microholes using laser technology and, consequently, the shape of the hole, can affect the flow losses. Therefore, this effect was investigated and the flow characteristics in both directions were measured, i.e., for two plate settings.

Development and Validation of a Three-Dimensional Multiphase Flow CFD Analysis for Journal Bearings in Steam and Heavy Duty Gas Turbines

2012 ◽  
Author(s):  
Stephan Uhkoetter ◽  
Stefan aus der Wiesche ◽  
Michael Kursch ◽  
Christian Beck
Keyword(s):  
Experimental Data ◽  
Multiphase Flow ◽  
Gas Turbines ◽  
High Speed ◽  
Three Dimensional ◽  
Air Entrainment ◽  
Journal Bearings ◽  
Heavy Duty ◽  
Present Contribution ◽  
Two Phase

The traditional method for hydrodynamic journal bearing analysis usually applies the lubrication theory based on the Reynolds equation and suitable empirical modifications to cover turbulence, heat transfer, and cavitation. In cases of complex bearing geometries for steam and heavy-duty gas turbines this approach has its obvious restrictions in regard to detail flow recirculation, mixing, mass balance, and filling level phenomena. These limitations could be circumvented by applying a computational fluid dynamics (CFD) approach resting closer to the fundamental physical laws. The present contribution reports about the state of the art of such a fully three-dimensional multiphase-flow CFD approach including cavitation and air entrainment for high-speed turbo-machinery journal bearings. It has been developed and validated using experimental data. Due to the high ambient shear rates in bearings, the multiphase-flow model for journal bearings requires substantial modifications in comparison to common two-phase flow simulations. Based on experimental data, it is found, that particular cavitation phenomena are essential for the understanding of steam and heavy-duty type gas turbine journal bearings.

Ship Component in Hull Optimization

2005 ◽  
Vol 39 (2) ◽  
pp. 39-46 ◽  
Author(s):  
Kent Davey
Keyword(s):  
Gas Turbines ◽  
Optimized Design ◽  
Power Train ◽  
Load Demand ◽  
Hull Optimization ◽  
Size Number ◽  
Component Identification ◽  
Electric Ship ◽  
Mission Profile ◽  
System Volume

This document outlines an optimization to define the size of the components in the power train of an electric ship, specifically one appropriate for an 80 MW Destroyer. The objective is to minimize the volume of the system, including the fuel. The size, number and speed of the gas turbines, the electric generators, and the power electronics are considered as unknowns in the analysis. At the heart of the procedure is the power mission profile. The gas turbine is by far the most important component in terms of influence on system volume. Integral to its selection is the specific fuel consumption as a function of power and turbine size. The proposed procedure outlines a nested optimization to define both the best spread of turbines as well as the proper scheduling with load demand. Including fuel in the system volume is the key to meaningful component identification. The optimized design has a system volume 603.5 m3 smaller than the base configuration, assuming both systems employ load scheduling among turbines. An optimized design can save as much as 600 m3.

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