SoundPLAN International LLC

- Version 7.4 - Aircraft Noise Module

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SoundPLAN is especially excited about two features which we will  highlight in discussions about version 7.4; one is the new developments for industry noise and the other is the data entry from measured radar tracks in the aircraft noise module. Of course, there are improvements throughout the program, but these are especially significant.

For industry noise, there are new developments for the directivity of sources and for the industrial building, and there is now the possibility to calculate the sound power of a source from technical parameters (pipe noise) or to calculate the sound power backwards from measured spectra. As the calculation from technical parameters and the backwards calculation requires Expert System Industry Noise, this module is on sale the second quarter of 2015, with a price reduction of  25%! The graphic above shows calculations using Expert System Industry Noise.

SoundPLAN has spent several years developing the capabilities to make the ever bigger noise maps feasible and practical. The time and energy was well spent demonstrated by SoundPLAN being used successfully for many huge projects, one being the END train noise maps for the entire country of Germany.

Now we turn our focus to further improving industrial noise calculations. We developed new ways to help with handling directivity, to extend the frequency range down to 1 Hz and to improve the industrial building. And there is more to come! Partitioning an industrial building into multiple rooms of different usage and the transmission of noise between them is underway. Plus the new developments such as encapsulated operator cabins and capsulated machines aades with SoundPLAN v8.0

A major step was taken in SoundPLAN 8.1 with the possibility to calculate the sound power from technical formulas. With this new capability it is possible to correctly calculate the noise from pipes in a refinery or chemical plant using the pipe description and data of the medium inside. This capability has been extended in v8.

SoundPLAN 8.1 also helps engineers with backwards calculations of the sound power from measured data in situations where it is not possible to acquire the direct measurement of the sound power.

Full Integration of Indoor Noise, Transmission and Propagation

Industrial buildings have roofs and walls, and often extra weak areas on the facades such as windows and doors. In our sample, there is also an opening where cars drive out of the car wash. The noise level on the inside of the building is the same for the 'normal' walls and for the open door; the difference is the transmission index. For normal walls, the transmission index for concrete walls was chosen. For the open door, a transmission index with 0.0 dB loss was chosen.

The sound power radiated by the building is calculate for each square meter of the facade. The formula is: Lw=Li-6- Transmission loss. The noise level indoors can come from a simulation, or, as in this case, from a measurement.

Depending on the scope of the study and the available data, you can enter the 'stream' at many different locations. If a full simulation of the noise levels indoors is the basis of your investigation, the program will generate receivers 1 meter inside the outer walls and calculate the noise levels for it. The noise levels are hosted in the emissions library.

1): The Facades of an industrial building with the superimposed area sources such as windows and doors. This tree of sub-objects depicts the outer shell of the industrial building. The original areas are the height of the building times the length of the facade.

2): The top view shows all facades, the roof and if the industrial building has the attribute 'floating building' the bottom. When stepping through the list of facades, the active facade is marked in the top view and the right hand side contains the projection along with all inserted sources.

3): The projection of the facade with the inlaid sources. Clicking on one of the inlaid sources opens the parameters for these sources along with the possibility to edit the coordinates.

4): The details of the Facade or inserted source with group definitions and the coordinates.

5): The acoustical source definition with the indoor sound pressure level, the noise transmission and the sound power level, frequencies and time histories. Please note each source can have up to 3 acoustical definitions. For example, a window can be open or closed with totally different transmission loss and directivities, etc..

6): Acoustical definitions for impulse, tonality, geometrical restrictions and maximum noise level.

7) Diagrams depicting the frequency distribution and the time history of the source.

New in 7.4:

  • Multiple definition for the sources (open/closed window)
  • Directivity for the sources
  • Time history and frequencies of the indoor modeling regarded with the environmental propagation
  • Direct entry of point, line and area sources on the facade
  • Industrial building with the possibility to be detached from the ground and noise passing underneath
  • With intermediate update: Industrial buildings radiating noise on all facades and top and also the bottom. This is for machines in boxes on industrial racks.

As regulations in several countries demanded, SoundPLAN extended the frequency range for lower frequencies to 1 Hz. Screening, ground effect and the air absorption have been corrected to exchange the frequency range.

 

SoundPLAN offers two different directivities - 2D and 3D. The values are defined every 10 degrees between 10 and 360. If the values are not entered every 10 degrees, an interpolation allows the values to be evaluated for the directions needed. With the 'Norm' button, the directivity values are assessed so the directivity does not scale the sound power up or down.

The 2D directivity comes in multiple variants - the usual horizontal directivity and the rotational symmetrical vertical directivity. The vertical directivity only uses the values in the 'eastern' half of the diagram, i.e. the values between 270°-0°- 90°. This vertical directivity is used for smoke stacks and openings that have a rotational symmetry. The rotation axis is always vertical.

The direction 0° of the 2D horizontal directivity is the main direction of the equipment. When digitizing the source, the main direction needs to be set under the 'additional' tab of the source definition.

If the directivity is more complex (the source is not only directive in the horizontal plane such as when using loud speakers), a full 3D directivity is available where the directivity is entered for 18 lines of latitude and for 36 values representing the entire 'globe' in steps of 10 degrees.

Not all equipment has the same directivity for all frequencies, so the directivity definition in the source has a checkbox to allow the directivity to be frequency dependant. Different directivity patterns can be assigned to a single frequency or groups of frequencies.

For highly directive sources such as signal horns and speakers, the directivity data can be imported from a standard format and a new 3D visualization presents the spherical directivity.

The handling of the directivity has been re-designed. Orienting the source is now done graphically in the GeoDatabase with windows of the XY plane and other projections.

Standard industry noise simulations use point, line and area sources. SoundPLAN exceeds this with two key features. The industrial building contains all facilities to simulate the noise breakout from an industrial building and users can attach additional point, line and area sources to the outer walls. The module to calculate noise from technical parameters also extends the standard capabilities. Here it is not the geometry but the calculation of the sound power.

In the upper left picture you see a pipeline with the internal noise levels decaying for each frequency at a constant rate of 0.02 dB per meter of length in the pipeline. As a result, the noise levels in the vicinity of the pipe drop from nearly 100 dB to 50 dB over 1.5 km.

For a single element, the sound power is defined with formulas in the library, by arithmetic expressions, and by using if / then / else program parts. User defined variables augment variables from the system such as the length of a line or the distance from the beginning of the line or the size of an area. The parameters of user defined variables are set in the source definition in the GeoDatabase. Variables can be single real numbers, integer, Boolean or spectral variables that are an array of real numbers.

The sources not only deliver the sound power used in the noise calculation, but they also deliver output variables of internal sound power where the output of one element is used as the input of another element. 

The noise calculation module is a general purpose module that allows users to define and calculate the noise from electrical motors, the noise from fans and compressors and the noise from pipes in accordance to ISO 15443/15665. As users can implement their own formulas, it is possible for companies to implement their own formulas and regulations into the library and use them with regular point and line sources.

For this feature the Expert Industry module is required.

Industry noise requires input of the sound power over frequency. These values can only come from simulations (see above) or from measurements. It is often very difficult to measure the sound power because the source (such as a flare on a high stack) is inaccessible or there are other strong sources in the vicinity and it is impossible to measure the sound power level from a source without employing intensity measurement techniques.

One example of this is a power house of a power plant. The building radiates noise, but the level per square meter is relatively low. Because the source is so big, it is still a relevant source and should be included in the model.

With SoundPLAN v7.4 Industry Expert, it is possible to assess the sound power level for multiple sources with multiple measurements. The influence of 'known' sources is evaluated for the measurement location, and when subtracted from the measured noise levels, the remaining noise levels reflect the noise caused by the 'unknown' sources. Using the least square error method, SoundPLAN finds the most likely sound power level for the 'unknown' sources. After defining these sources, they can be used in the calculation for noise maps for the outside of the plant area.

The top left picture shows the entry of measurement points with spectral information. There have to be at least as many measured spectra as there are unknown sources in the system. The bottom picture shows the results of the sound power calculation for one of the sources. The top of the box shows the list of all simulated sources, the sum Lw, mean deviation and the contributions frequency by frequency.

For industrial noise calculations, SoundPLAN offers point, line and area sources and an industrial building. Sources can be mid-frequency, octave bands or third octave bands. The ranges can be between 25 Hz and 20 kHz. The industrial building allows for the simulation inside as well as the transmission through the outside walls.

New in SoundPLAN 7.4: dedicated Wind Turbine with entry and calculation in accordance to ISO 9613, ÖNORM ISO 9613-2 and the UK-Institute of Acoustics model for wind turbines. The library now contains standard wind turbines with their acoustical data and the height of the hub and the rotor diameter. As the sources can be placed directly on top of a DGM with the attribute 'terrain referenced', it is very easy to make a model for wind turbines.

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Now buildings and industrial buildings can act like floating screens with noise passing underneath. The requirement is to ensure the building has this attribute enabled: 'Building floats above ground.' This also means you can now model stacked buildings with Facade Noise Maps - even for the part with a smaller footprint, as you can see to the left.

Aircraft in the vicinity of an airport are controlled by air traffic control. Especially for the approach into an airport, the path of the aircraft is dominated by the need of air traffic control to separate aircraft coming to an airport at random times and placing them into a chain that has regular spacing. As an aircraft's speed or angle of decent is not widely controllable, the best way to get this constant separation is to have aircraft fly slightly different paths.

The random approach of five aircraft into London Heathrow shows the problem. Of the five aircraft arriving simultaneously, four are flying toward London from the east, but use different flight paths to separate them properly. The actual paths will deviate significantly from the theoretical ones, so the noise levels between the actual and the theoretical paths will also vary .

The random picture of 5 aircraft is not any different than the superimposed view of all approaching and departing aircraft of a period of a day or a week as can be seen in the lower picture. It is easy to see that entering all the different path would be very time consuming, especially as the paths are not entered with coordinates but with elements as straight flight and turns (most of them standard turns) to the left and to the right.

The elevation profile depends on the aircraft type because certain speeds and decent rates are standard for commercial aircraft. For a departing aircraft, the paths are more straightforward, but the climb rate depends on the type of aircraft, the type of engines, and the weight of the aircraft. Entering all these factors for many aircraft is very time consuming, so we developed two different methods to accommodate for variation in the path. The theoretical path is considered a corridor, and for each corridor there are multiple paths which are considered using a standard distribution. For more variation in existing airports, the entry from radar tracks is becoming an increasingly popular tool.

For management and simulations of aircraft noise, a record of the aircraft position and flight status is needed. Most larger airports also measure and document the noise associated with aircraft. SoundPLAN does not need the noise data but does need the position, elevation and speed information, and references to the type of aircraft and the aircraft configuration for noise simulations.

Topsonic is a prime example of a supplier for such a noise monitoring and collection system. More information about Topsonic systems: http://topsonic.aero/en. This noise monitoring system is used throughout Germany and also in Europe and Asia.

The data from the Topsonic Aircraft Noise and Flight Track Monitoring System are recorded in a format SoundPLAN can import and use to calculate all individual flight events or to generate generalized backbones from these databases.

For airport noise control officers, both the noise monitoring and the simulated tracks are very helpful. Noise monitoring shows only noise events; it is not possible to directly assign the noise to a specific aircraft. Only in conjunction with a noise simulation from a noise modeling software like SoundPLAN is it possible to separate noise from the aircraft from noise from the other sources in the environment creating the noise event.

The track data X,Y and Z do not describe the aircraft as a noise source. Instead, SoundPLAN uses the coordinate information, the type information and the speed of the aircraft during import of the track data to identify the acoustical emissions. The vertical flight profile is compared with procedural profiles stored for each aircraft class. These profiles allow the deduction of throttle settings and the flight configuration of the aircraft. Very good agreement has been attained between simulation and noise monitoring by importing the radar tracks for the Frankfurt airport in the framework of the NORAH study.

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All Calculations in SoundPLAN are based on standards. Below is a list of standards implemented in SoundPLAN v7.4 for aircraft noise and helicopter noise.

SoundPLAN is a unique noise modeling software that allows a comprehensive view of noise. This means that for SoundPLAN noise from flying aircraft is not a separate problem disconnected from other noise sources like it is in the software called INM from the United States.

SoundPLAN can produce comprehensive noise maps of flying and taxiing aircraft, engine test facilities, auxiliary power units, baggage handling, air conditioning and all transport related sources around an airport.

Often aircraft noise is not evaluated stand alone but is seen as an addition to the ambient noise levels found in the vicinity of the airport. Evaluations state there is not only a noise limit for aircraft, but also take into account how many dB the aircraft increase the ambient noise levels.

SoundPLAN version 7.4 is ready for you! Every SoundPLAN user with a new license (less than 12 months old) or with Update & Maintenance services will receive a DVD for a free upgrade. The DVDs are sent from our office to your local distributor to dispatch to you, so please be patient during the shipping period. But you can also to our website to download v7.4: www.soundplan.eu/english/demo-versions  The download has less examples and less of the extra information that the DVD, but you can get started using the new features before your DVD arrives. If you need the 64 bit version, you will have to wait for the DVD, though.

Because SoundPLAN 7.4 must be installed as a new version, you do not have to uninstall previous versions. Once installed, additional updates can be downloaded from the SoundPLAN Managers help menu under the Updates&Downloads section.

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