Sound energy diverter to reduce platform noise of railway vehicles

Abstract

The sound energy deflector (1) is composed of three positions; a rectangular frame (1b) of four strips of sheet metal U-profile with two curves or a curved L-profile + position (1a) in the function of a wall when the axial jet hits and for its radial deflection against the wall + a group of sheet metal plates (1c) between (1b) and (1a) whose axial distance is (C) ). The positions are arranged so that the initial part of the air flow channel to the entrance between the sheets from group (1c) is a confuser (with a gradually reduced channel cross-section), and behind it is most of the flow channel parts in the form of a diffuser. It is applied behind a rectangular opening of size axb for the air outlet from the assembly (2), as a sound source, when the sound energy at that opening is the cause of unacceptable noise in prescribed places. One example is a rail vehicle with a fan on the roof of the vehicle, and the maximum noise on the platform, i.e. at a given distance from the center of the rails, is prescribed.The application of the invention is particularly useful in the case where the two horizontal sides of the opening are parallel to the rails, and in addition the sound energy at the opening significantly affects the prescribed platform noise. When the opening of size axb on the fan assembly is the same as the opening (a1xb1) on the rectangular frame (1b) made of two pairs of frame strips (2b1) and (2b2) ​​made of L-profiles, but it is often a more favorable solution with an opening (a1xb1), smaller than the size axb, when a U-profile is used whose smaller radial arm has a rim in the shape of a rectangle of size (a1xb1), i.e. the same as the opening of size axb on assembly 2, and the longer arm of the profile has a rim (A1xB1), which is smaller than the rim (AxB) at position (1a), which has the function of a wall. The simplest first embodiment of the switch (1) is according to patent claim 1, when the longer arm of the profile for four tracks is radial, and position (1a) is a rectangular plate (AxB). Sometimes a more complex second version of the switch (1) according to claim 2 is required.In this case, parts of the radial arms of the four-strip profile (1b1) and (1b2) and part of position (1a) above the beginning of the sheets (1c) need to be bent at angles, for which experiments or flow simulation gives more favorable results. When it is necessary to reduce the sound energy during the impact and deflection of the jet (a1xb1) against the wall, for position (1a), an even more complex third design of the diverter (1) according to patent claim 3 is applied, when a layer of plastic material that absorbs part of the sound energy is fixed to the sheet from (1a). In this solution, position (1a) is therefore of sandwich design. The sound energy diverter (1) is composed of three positions; a rectangular frame (1b) of four strips of U-profile sheet metal with two curves or a curved L-profile + position (1a) in the function of a wall when the axial jet hits and for its radial deflection against the wall + a group of sheet metal plates (1c) between (1b) and (1a) whose axial distance is (C).The positions are arranged so that the initial part of the air flow channel to the entrance between the sheets from group (1c) is a confusor (with a gradually reduced channel cross-section), and most of the flow channel parts in the form of a diffuser is behind it. It is applied behind a rectangular opening of size axb for the air outlet from the assembly (2), as a sound source, when the sound energy at that opening is the cause of unacceptable noise in prescribed places. One example is a rail vehicle with a fan on the roof of the vehicle, and the maximum noise on the platform, i.e., at a given distance from the centre of the rails, is prescribed. The application of the invention is particularly useful in the event that the two horizontal sides of the opening are parallel to the rails, and in addition, the sound energy at the opening significantly affects the prescribed platform noise.When the opening of size axb on the fan assembly is the same as the opening (a1xb1) on the rectangular frame (1b) from two pairs of frame strips (2b1) and (2b2) of the L-profile, but it is often a more favourable solution with the opening (a1xb1), smaller than the size axb, when using a U-profile whose smaller radial arm has a rim in the shape of a rectangle of size (a1xb1), therefore the same as the opening of size axb on assembly 2, and the longer leg of the profile has a rim (A1xB1), which is smaller than the rim (AxB) at position (1a), which has the function of a wall. The simplest first version of the switch (1) is according to patent claim 1, when the longer leg of the four-lane profile is radial, and position (1a) is a rectangular plate (AxB). Sometimes a more complex second version of the switch (1) according to requirement 2 is needed.In this case, the parts of the radial arms of the profile of the four strips (1b1) and (1b2) and the part of the position (1a) above the beginning of the sheets (1c) need to be bent at angles, for which experiments or flow simulation give more favourable results. When it is necessary to reduce the sound energy during the impact and deflection of the jet (a1xb1) against the wall, for position (1a), an even more complex third version of the diverter (1) according to patent claim 3 is applied, when a layer of artificial substance is attached to the sheet metal (1a), which absorbs part of the sound energy. In this solution, therefore, position (1a) is a sandwich design.