Type line design and check method for impeller meridian plane of radial-axial turbine expander

Abstract

The invention discloses a type line design and check method for an impeller meridian plane of a radial-axial turbine expander. The type line design and check method comprises the following main steps of reading in basic parameters of the impeller meridian plane; selecting a two-dimensional coordinate system of the meridian plane; calculating point coordinates of an input and an exit of a hub and shroud curve; giving an initial equation index value by adopting a generalized elliptic equation according to known parameters and solving a hub and shroud curvilinear equation; solving the arc length of the curve from the input to the output, dividing the arc length of the curve into N equal parts, solving the coordinates of equal diversion points according to the curvilinear equation, thus calculating the through-flow area at constant current contour position, and drawing with the flow line position as a horizontal coordinate and the through-flow area of the flow line position as a longitudinal coordinate; judging whether a flow channel meets the requirement or not, if so, outputting the point coordinates of the hub and shroud curve of the meridian plane, and if not, adjusting curvilinear equation indexes ph and qh or ps and qs and recalculating. According to the method provided by the invention, the design process is simpler, more convenient and quicker; the reference for checking smoothing changes of the flow channel is more visual and reliable; in addition, the processing and the manufacturing of subsequent impellers are facilitated.

Description

technical field [0001] The invention relates to the design of the meridian surface of a turbomachinery impeller, in particular to a design and checking method of the meridian surface of the impeller of a radial-axial flow turboexpander. Background technique [0002] The impeller is the main flow part of the turbomachinery, and its performance has a decisive effect on the performance of the whole machine. The shape of the meridian surface directly affects the flow structure inside the impeller. In the radial and axial flow turboexpander, the traditional method is to The meridian surface curve is regarded as composed of circular arc and straight line segments. On the basis of empirical data, the radius of the circular arc is estimated to construct the meridian surface, and then the flow channel of the meridian surface is expanded with drawing software and checked with a series of enveloping circles. Gradually corrected to a smooth changing flow path. This geometric modeling m...

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Problems solved by technology

This geometric modeling method has three disadvantages: First, the traditional design method is a drawing and trial method. If one of the envelope circles cannot meet the smooth condition, it is necessary to modify the shape of the flow channel and start from the entrance to make the envelope circle again. check, or when there are a large number of candidate impellers, it is necessary to design and check the enveloping circle of these impeller meridians one by one, which makes the workload relatively large; the second is that the check in the traditional design method expands the flow path Whether the tangent line on both sides of the back envelope circle is close to a straight line is used as the basis for smooth change. This method is limited to two-dimensional judgment, and the flow area of ​​the three-dimensional downflow channel has not been calculated. The judgment basis is not convincing enough; the third is The traditional design and verification method needs to be realized by drawing, without digitalization, it is not convenient for follow-up work such as three-dimensional forming and processing of the overall impeller and numerical simulation of the flow channel

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