Rail Vehicle Sand Spreading Nozzle Design
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Solution Overview
Problem
Existing sand spreading devices for rail-bound vehicles are inefficient in using compressed air, as they require a large amount of air to suck in and blow out sand, especially with heavier grains, due to suboptimal nozzle designs that lead to turbulence and increased air resistance.
Innovation Solution
The design features a cylindrical bore suction nozzle with a length equal to or greater than its diameter, a short distance between the nozzle inlet and outlet, and a conically widened section to reduce turbulence, along with additional air supply at the nozzle end and an annular gap for uniform air distribution, enhancing the flow properties and suction efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If conventional nozzle designs are used, then sand can be conveyed, but compressed air consumption is high due to turbulence and increased air resistance
Solution Approach 1:
The suction nozzle parameters are optimized by setting the length L to be between 0.5d to 2d (where d is the diameter), and the distance a from the inlet opening to the compressed air inlet is set to less than twice the inner diameter. These parameter changes reduce turbulence and air resistance, thereby reducing compressed air consumption while maintaining sand conveyance efficiency.
Solution Approach 2:
The suction nozzle is designed with a cylindrical bore rather than sharp edges or abrupt transitions. This curved, cylindrical geometry reduces turbulence and improves flow properties, leading to lower compressed air consumption while maintaining effective sand conveyance.
2Stability of the object's composition
If the suction nozzle protrudes far into the mixing space, then sand staircase formation improves, but the nozzle may interfere with sand flow
Solution Approach 1:
The protrusion distance of the suction nozzle into the mixing space is optimized to form a sand staircase while avoiding interference with sand flow. The cylindrical bore design with specific length-to-diameter ratio allows the nozzle to extend into the mixing space sufficiently to create the staircase effect without creating harmful flow interference.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This configuration improves the flow properties and suction efficiency, allowing for a larger amount of sand to be sucked and blown out with the same compressed air consumption or requiring less air for the same amount of sand, ensuring a uniform sand distribution between the wheel and rail.
Implementation Method 1
air and sand are usually sucked in from a storage container by means of compressed air-operated jet pumps
Implementation Method 2
The jet pump consists of a nozzle (driving nozzle), an injection space (mixing space) and an arrangement called a 'Venturi tube'
Implementation Method 3
The length of the cylindrical bore within the suction nozzle is at least equal to the size of the diameter of the cylindrical bore in the suction nozzle... This design significantly improves the flow properties inside and outside the suction nozzle
Implementation Method 4
a mixing device adjoining the outlet with a mixing space provided for whirling up the bulk material using compressed air
Implementation Method 5
a conically widened section at the nozzle end for reducing flow resistance and enhancing sand acceleration
Data Source
Figure 1
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AI summary
A scattering device (1) for spreading bulk material, in particular braking sand, at railborne vehicles, with a storage container, an outlet on the storage container, a mixing device (3) which adjoins the outlet and has a mixing space (4), an inlet (5) for the supply of compressed air, and an outlet (10), leading to a discharge device (9), in the mixing device (3), wherein a suction nozzle (11) to which the discharge device (9) is connected is provided at the outlet (10), wherein the nozzle duct (12) of the suction nozzle (11) is formed by a cylindrical bore (14), wherein the length (L) of the cylindrical bore (14) within the suction nozzle (11) is at least equal to the size of the diameter (d) of the cylindrical bore (14) in the suction nozzle (11), wherein the distance (a) of the suction nozzle (11) or of the inlet opening (16) in the suction nozzle (11) to the outlet opening (7) of the inlet (5) for the supply of compressed air in the mixing device (3) is smaller than twice the size of the inside diameter (d) of the cylindrical bore (14), and wherein, in order to form a sand stairway in the mixing space (4), the suction nozzle (11) projects at the end (15) thereof that faces away from the discharge device (9) into the mixing space (4) to an extent such that that end (15) of the suction nozzle (11) which faces away from the discharge device (9) is arranged in the mixing space (4) above the outlet opening (17) of the outlet.