Turbine Noise Reduction: Axial Spacing and Embedded Design

2015 ◽  
Author(s):  
C. Faustmann ◽  
S. Zerobin ◽  
S. Bauinger ◽  
A. Marn ◽  
F. Heitmeir ◽  
...  
Keyword(s):  
Power Level ◽  
Low Pressure ◽  
Sound Power ◽  
Noise Generation ◽  
Turbine Stage ◽  
Noise Emission ◽  
Low Pressure Turbine ◽  
Sound Power Level ◽  
Embedded Design ◽  
Lp Turbine

This paper deals with the investigation on the acoustics of different turning mid turbine frames (TMTF) in the two-stage two-spool test turbine located at the Institute for Thermal Turbomachinery and Machine Dynamics (ITTM) of Graz University of Technology. The facility is a continuously operating cold-flow open-circuit plant which is driven by pressurized air. The flow path consists of a transonic turbine stage (HP) followed by a low pressure turbine stage made of a turning mid turbine frame (TMTF) and a counter-rotating low pressure rotor. Downstream of the low pressure turbine a measurement section is instrumented with acoustic sensors. Three TMTF setups have been investigated at engine like flow conditions. The first configuration (C1) consists of 16 highly 3D-shaped turning struts. The goal of the second design (C2) was to reduce the length of the TMTF by 10% without increasing the losses and providing comparable inflow to the LP turbine rotor. This was achieved by applying 3D-contoured endwalls at the hub. The third one (C3) is a new embedded concept for the turning mid turbine frame with two zero-lift splitters placed into the strut passages. In total 48 vanes (16 struts plus 32 splitter vanes) guide the flow from the HP rotor to the LP rotor. The comparison in terms of noise generation and propagation of the turbines is done by the microphones signal spectra, the emitted sound pressure and sound power level of each TMTF setup. Therefore the acoustic field is characterized by azimuthal and radial modes by means of a microphone array at the outer casing traversed over 360 degrees. By comparing the first two setups (C1 and C2) in terms of noise generation the propagating modes due to the HP turbine were found to be the same, while a difference of 5 dB in amplitude of the modes related to the LP turbine was found due to the different axial spacing between both setups. In the multi-splitter configuration (C3), the overall sound power level depending on the blade passing frequency (BPF) of the HP turbine is reduced by 7 dB and depending on the BPF of the LP turbine by 4 dB compared to C1, respectively. The overall effect is a reduction of the noise emission for the HP turbine due to the embedded design as well as for the LP turbine due to increasing the axial spacing between the TMTF Vanes and LP Blades on the one hand and considerably due to the embedded design on the other hand.

Experimental Investigation of the Noise Generation and Propagation for Different Turning Mid Turbine Frame Setups in a Two-Stage Two-Spool Test Turbine

2013 ◽  
Author(s):  
C. Faustmann ◽  
D. Lengani ◽  
R. Spataro ◽  
A. Marn ◽  
E. Göttlich ◽  
...  
Keyword(s):  
Microphone Array ◽  
Low Pressure ◽  
Open Circuit ◽  
Noise Generation ◽  
Turbine Stage ◽  
Noise Emission ◽  
Two Stage ◽  
Low Pressure Turbine ◽  
Lp Turbine ◽  
Eu Project

The paper deals with the investigation of the noise generation in the two-stage two-spool test turbine located at the Institute for Thermal Turbomachinery and Machine Dynamics (ITTM) at Graz University of Technology. The rig went into operation within the EU-project DREAM, where the target was to investigate the aerodynamics of interturbine flow ducts. The facility is a continuously operating cold-flow open-circuit plant which is driven by pressurized air. The flow path contains a transonic turbine stage (HP) followed by a low pressure turbine stage consisting of a turning mid turbine frame and a counter-rotating LP-rotor. Downstream of the low pressure turbine a measurement section is instrumented with acoustic sensors. The acquisition system consists of a fully circumferentially traversable microphone array located at the outer casing, while at the hub endwall a stationary flush mounted microphone is placed as a reference. Additionally a new embedded concept for the turning mid turbine frame was tested. Here, two zero-lift splitters were located into the vane passage. In order to evaluate the noise emission of the turbine the facility was instrumented with a new acoustic measurement setup which is presented in the paper. Therefore the emitted sound pressure level and the microphones signal spectra are compared for both configurations. The acoustic field was characterized by azimuthal modes by means of a microphone array traversed over 360 degrees. In the multisplitter configuration, the propagating modes due to the HP turbine are found suppressed by 5 dB, while the increase in amplitude of the modes related to the LP turbine is negligible. The overall effect is a reduction of the acoustic emission for the turning mid turbine frame with embedded design.

scholarly journals A simulation of traffic noise emissions at a roundabout based on a cellular automaton model

Acta Acustica ◽  
2021 ◽  
Vol 5 ◽  
pp. 42
Author(s):  
Canyi Du ◽  
Xinfa Qiu ◽  
Feng Li ◽  
Ming Cai
Keyword(s):  
Cellular Automaton ◽  
Road Traffic ◽  
Power Level ◽  
Traffic Noise ◽  
Traffic Volume ◽  
Sound Power ◽  
Noise Emission ◽  
Urban Road ◽  
Speed Distribution ◽  
Sound Power Level

The calculation and evaluation of traffic noise is an important task in urban road design. Roundabouts are a common form of urban road intersection. The complexity of traffic operations makes the calculation of traffic noise near a roundabout challenging. To explore traffic noise at roundabouts, a cellular automaton traffic flow model for a two-lane roundabout is established. Based on this model, a dynamic simulation method for traffic noise at roundabouts is proposed. The traffic operation and noise emissions at a roundabout are simulated. The vehicle speed distribution and traffic noise distribution at the roundabout are analysed, and the relationship between the traffic volume and sound power level of the cells is discussed. Finally, the proposed method is compared with existing traffic noise models, and the accuracy and efficiency of the proposed method are verified. The results of this paper show that the speed distribution and noise emission distribution at the roundabout are not uniform. When the traffic volume increases to saturation, the noise emission on the ring road will not keep increasing, and the sound power level of the cells on the inner ring is approximately 2 dBA higher than that of the outer ring. The methods and results in this paper may be valuable for road traffic design and noise control.

scholarly journals Trailing Edge Thickness Effect on Tonal Noise Emission Characteristics from Wind Turbine Blades

2021 ◽  
Vol 13 (4) ◽  
pp. 99-111
Author(s):  
Satya Prasad MADDULA ◽  
Vasishta Bhargava NUKALA ◽  
Venkata Swamy Naidu NEIGAPULA
Keyword(s):  
Wind Turbine ◽  
Power Level ◽  
Turbine Blades ◽  
Broadband Noise ◽  
Thickness Effect ◽  
Sound Power ◽  
Noise Generation ◽  
Wind Turbine Blades ◽  
Trailing Edge ◽  
Sound Power Level

Broadband noise generation from wind turbine blades is one of the fundamental aspects of flow-induced noise. Besides the turbulent boundary layer flow over the blades, factors such as the angle of attack, the turbulence intensity, the trailing edge thickness of the blade and their shapes strongly influence the overall sound power levels at high frequencies, i.e. f > 8 kHz. In large operating wind farms, a trade-off between noise generation and power production is considered by power utility firms to maximize the return on investment (ROI) and minimize the fatigue damage on wind turbine components. The present work deals with the analysis of the thickness effect on trailing edge bluntness noise level at hub height average wind speeds of 7 m/s, 10 m/s. A semi-empirical BPM model was used to predict the sound pressure levels from the 37 m blade length of a 2MW wind turbine. The receiver configuration was fixed at a distance of 120 m from the source height of 80 m. The results demonstrated that as the trailing edge height increased from 0.1 % to 0.5 % of the local chord, the sound power level increased by ~ 17 dB for frequencies > 200 Hz, but decreased by 16 dB when the thickness is 0.1 % local chord. The computed results of the sound power level using the BPM model have been validated using experimental data and showed a good agreement for the tonal frequencies, f ~ 10 kHz, where the trailing edge bluntness noise becomes dominant.

Analysis of the Sound Power Level Emitted by Portable Electric Generators (Outdoor Powered Equipment) Depending on Location and Measuring Surface

2013 ◽  
Vol 430 ◽  
pp. 266-275 ◽  
Author(s):  
Elena Postelnicu ◽  
Valentin Vladut ◽  
Cristian Sorica ◽  
Petru Cardei ◽  
Ion Grigore
Keyword(s):  
Noise Source ◽  
Power Level ◽  
Acoustic Power ◽  
Sound Power ◽  
Noise Emission ◽  
Sound Power Level ◽  
Measuring Surface ◽  
Measurement Surface ◽  
Electric Generators

Acoustic power is a measure which must be specified on the outdoor used equipments and its determination depends on several factors: the place where the equipment works (indoor or outdoor), the placement of the microphones for its determination (the distance less or greater from the noise source), the shape of the measurement surface (parallelepiped or hemispherical). This paper aims to analyze the values obtained in these situations and interpret the data to determine the influence that each factor has on the acoustic power compared with the values obtained (permissible) according to Directive regarding noise emission D 2000/14/EC.

Experimental Study on the Aeroacoustic Behavior of a Forward-Curved Blades Centrifugal Fan

1999 ◽  
Vol 121 (2) ◽  
pp. 276-281 ◽  
Author(s):  
Sandra Velarde-Sua´rez ◽  
Carlos Santolaria-Morros ◽  
Rafael Ballesteros-Tajadura
Keyword(s):  
Flow Rate ◽  
Power Level ◽  
Operating Conditions ◽  
Aerodynamic Noise ◽  
Sound Power ◽  
Noise Generation ◽  
Centrifugal Fan ◽  
Tonal Noise ◽  
Sound Power Level ◽  
Starting Point

In this paper, an aeroacoustic study on a forward-curved blades centrifugal fan has been carried out. As a first step, the fan performance curves, i.e., total pressure, power, efficiency and sound power level versus flow rate were obtained, showing its unstable behavior over a wide operating range. Second, the fan sound power level spectra for several working conditions were determined. For this purpose a normalized installation for testing in laboratory was designed and constructed. Afterwards, the velocity and pressure fields, both at the inlet and outlet planes of the impeller were measured using hot wire probes and pressure transducers, for different operating conditions. Finally, the aeroacoustic behavior of the fan was determined measuring the vorticity field at the impeller outlet, which is known to be related to tonal noise generation. This relation is worked out using the theory of vortex sound, developed by several authors during the second half of this century. The paper shows that the generation of tonal noise is produced at the blade passing frequency and it increases with the flow rate. Although the main contribution to fan noise generation is due to mechanical sources, the bands in which aerodynamic noise is generated by these fans correspond to frequencies especially unpleasant to the human ear. Therefore, the research presented in this paper may be of considerable interest, establishing a starting point for the design of quieter and more efficient fans.

Aerodynamics and Acoustics of Turning Mid Turbine Frames in a Two-Shaft Test Turbine

2014 ◽  
Author(s):  
C. Faustmann ◽  
E. Göttlich
Keyword(s):  
Pressure Loss ◽  
Low Pressure ◽  
Turbine Rotor ◽  
Open Circuit ◽  
Point Of View ◽  
Turbine Stage ◽  
Cold Flow ◽  
Low Pressure Turbine ◽  
University Of Technology ◽  
Lp Turbine

The paper deals with the investigation on the aerodynamics and the acoustics of two different turning mid turbine frames (TMTF) in the two-stage two-spool test turbine located at the Institute for Thermal Turbomachinery and Machine Dynamics (ITTM) of Graz University of Technology. The facility is a continuously operating cold-flow open-circuit plant which is driven by pressurized air. The flow path consists of a transonic turbine stage (HP) followed by a low pressure turbine stage made of a turning mid turbine frame (TMTF) and a counter-rotating low pressure rotor. The two TMTF setups have been investigated at engine like flow conditions. The first configuration consists of 16 highly 3D-shaped turning struts. The goal of the second design was to reduce the length of the TMTF by 10% without increasing the losses and providing comparable inflow to the LP turbine rotor. This was achieved by applying 3D-contoured endwalls at the hub. To estimate the pressure loss over the duct aerodynamic measurements are performed at the inlet and the outlet of both turning mid turbine frames by using 5-hole probes (FHP) and total pressure rakes. The FHP-measurements at the inlet of the TMTF were performed in three different ways to obtain the influence of probe positioning and traversing on the results. While the 5-hole probe was traversed only in a sector the rakes were traversed over the full circumference. The comparison between the two turning mid turbine frame setups shows from an aerodynamic point of view that it is possible to reduce the engine weight by designing a 10% shorter TMTF with endwall contouring providing the same pressure loss and comparable inflow conditions for the LP turbine rotor. Due to the fact that noise becomes more and more an issue additional acoustic measurements were carried out downstream of the low pressure turbine. By comparing the two setups in terms of noise generation the propagating modes due to the HP turbine were found to be the same, while an increase of 10dB in amplitude of the modes related to the LP turbine was found in the 10% shorter setup. This is in good accordance with previous studies, where reducing the distance between stator and rotor increases the emitted sound.

Sound Intensity Mapping on Single Cylinder Direct Injection Diesel Engine with The Application of Palm Oil Methyl Ester Biodiesel

2021 ◽  
Vol 18 (2) ◽  
pp. 8833-8844
Author(s):  
Mohd Shahrir Mohd Sani ◽  
J.M. Zikri ◽  
A. Abdul Adam
Keyword(s):  
Methyl Ester ◽  
Palm Oil ◽  
Engine Speed ◽  
Power Level ◽  
Sound Intensity ◽  
Sound Power ◽  
Noise Emission ◽  
Emission Analysis ◽  
Intensity Mapping ◽  
Sound Power Level

The utilisation of biodiesel nowadays has become familiar with rapid production types of biodiesel in order to replace the dependency on the fossil fuel parallel to the implementation of green technology that emphasises the products to be more environmental-friendly. Nevertheless, the emerges of various kinds of biodiesel cannot be simply used, despite using the biodiesel does not need any major modification on the engine; it still needs a few analyses that must be done to determine whether it will give advantages or disadvantages. Therefore, this research was carried out to investigate the effect of using palm oil methyl ester (POME) biodiesel on the engine in terms of noise emission. The sound intensity mapping method was used to indicate the effectiveness of the biodiesel by identifying the noise radiation. Along with the mapping, the sound power level (SPL) is also being obtained to provide a clear comparison between the parameters. Generally, switching up the engine speed and load increased the sound power level. Based on the results obtained related to the SPL, the intensity mapping tends to show a higher colour-coded in the noise source image for the higher engine speed and load setup. It was found that the engine speed and load give a significant contribution to noise emission produced by the engine, and it can be inferred that this method can be utilised to accomplish the noise emission analysis.

Measurement and Assessment on Environmental Noise Impact of Electric Vehicles in Accelerating Condition

2021 ◽  
Vol 263 (2) ◽  
pp. 4199-4210
Author(s):  
Katsuya Yamauchi ◽  
Jo Yoshino
Keyword(s):  
Electric Vehicles ◽  
Combustion Engine ◽  
Power Level ◽  
Environmental Noise ◽  
Sound Power ◽  
Vehicle Speed ◽  
Noise Emission ◽  
Sound Power Level ◽  
Noise Impact ◽  
The Difference

Noise emission from the vehicles propelled by electric system (such as pure electric and hybrid electric vehicles, EVs) is usually lower than the conventional internal combustion engine vehicles. Some previous studies have been shown the difference in A-weighted sound power level of EVs from the conventional ones. The difference is not dramatically large, i.e. less than 4 dB when the cars running at constant speed of 20 km/h. In this paper, we present the additional measurement results of sound power level of EVs in accelerating condition. Because when the cars in accelerating condition, the difference of propulsion systems becomes more significant on noise emission. The results are shown as regression model of sound power level depending on the vehicle speed. Moreover, the environmental noise impact of growing population of EVs is assessed through a prediction of at a case of intersection.

Acoustic Mode Analysis: Numerical and Experimental Results of a Turning Mid Turbine Frame

2016 ◽  
Author(s):  
S. Zerobin ◽  
P. Bader ◽  
C. Faustmann ◽  
A. Marn ◽  
E. Göttlich ◽  
...  
Keyword(s):  
Sound Pressure ◽  
Power Level ◽  
Low Pressure ◽  
Acoustic Mode ◽  
Experimental Results ◽  
Mode Analysis ◽  
Noise Generation ◽  
Turbine Stage ◽  
Specific Test ◽  
Frequency Spectra

In the present paper, a comparison of the numeric and experimental results obtained from the acoustic mode analysis for a turning mid turbine frame (TMTF) is presented. The investigated turning mid turbine frame is part of the two-stage two-spool test turbine located at the Institute for Thermal Turbomachinery and Machine Dynamics of Graz University of Technology. In this specific test turbine a transonic turbine stage (HP) is followed by a low pressure turbine stage (LP) consisting of a TMTF with 16 highly 3D-shaped turning struts and a counter-rotating low pressure rotor. The experimental dataset is obtained by a measurement section downstream of the low pressure rotor which is instrumented with acoustic sensors. This microphone array is wall flush mounted in the outer casing which is traversable over 360 degrees in circumferential direction. The numerical setup consists of the whole test turbine including the experimental measurement section downstream of the low pressure rotor. Since the periodicity of the test setup equals 90 degrees the CFD calculations were performed accordingly using the unsteady inhouse Navier-Stokes code LINARS. For both, numerical and experimental datasets the same post-processing tools are used in order to perform the acoustic mode analysis of the unsteady data. At first a comparison in terms of noise generation and propagation of the results is done by the frequency spectra, the emitted sound pressure and sound power level of both rotors independently. Since the emitted sound pressure level rises to a maximum at the first blade passing frequency of the HP rotor as well as the LP rotor the further analysis focuses on these two specific frequencies only. Therefore the acoustic field at those frequencies is characterized by azimuthal and radial modes. For a correct comparison between the numerical and experimental results numeric data taken from the same geometric locations as the microphones’ positions (thus the measurement locations) is processed. Hence, this paper provides a deep insight into the capability of using unsteady CFD calculation in combination with the acoustic mode analysis in order to obtain the noise generation and propagation in turbines.

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