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Non-steady flow simulating method for pipe network system

A non-constant flow, analog method technology, applied in instruments, computing, electrical and digital data processing, etc., can solve the problem of low simulation accuracy, and achieve the effect of simple coding, fast calculation speed, and simplified calculation complexity

Active Publication Date: 2013-12-18
WUHAN UNIV
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  • Description
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  • Application Information

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Problems solved by technology

[0008] Based on the above analysis, the existing simulation methods are used for unsteady flow simulation of complex pipeline systems, and the simulation accuracy is not high

Method used

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  • Non-steady flow simulating method for pipe network system

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0132] In the piping system, non-prismatic pipes are solved by implicit difference method and other pipes are solved by explicit difference method.

[0133] The draft tube is a non-prismatic pipe, and its pressure value is an important adjustment parameter in the transition process of the hydropower station. The draft tube is a flow passage with variable cross-section. Excessive negative pressure in the draft tube of the hydropower station will lead to the instability of the steel lining. , water column separation and other unfavorable phenomena, too low pressure may also lead to the release of gas in the water body, and the resulting impact pressure will cause cavitation and vibration of the turbine runner. The flow and moment characteristics of the turbine are generally determined by the comprehensive characteristic curve of the runner model under stable conditions. These characteristic curves do not include the influence of the inertia of the water flow under the unstable co...

Embodiment 2

[0135] In the piping system, the surge chamber is solved by the implicit difference method, and the other pipes are solved by the explicit difference method.

[0136] Using the method of the present invention to solve the surge in the surge chamber mainly includes two steps: the first step is to jointly solve the problem by using the explicit difference method and the implicit difference method; the second step is to use the implicit dynamic grid to track the free water surface of the surge chamber.

[0137] See Figure 10 The surge chamber and pipeline shown in the figure, the upstream and downstream pipelines of the surge chamber are solved by the characteristic line method, and the surge chamber is solved by using the Preissmann four-point implicit scheme after discretization.

[0138] The surge chamber is divided into n sections, and the end section n is the free water surface. In the case of grid determination, the water head H n It is known that the supplementary equat...

Embodiment 3

[0157] In the pipeline system, the implicit scheme difference method is used to solve the pipeline with full flow, and the explicit scheme difference method is used to solve the pipeline with subflow.

[0158] The basic equations of unsteady flow in open channels can be solved using explicit and implicit difference schemes. The explicit difference scheme is mainly the characteristic line method. First, the solution must satisfy the Courant condition, the time step is limited, and the numerical stability is difficult to guarantee ; Second, interpolation is required, and interpolation errors are unavoidable, especially when the transient process is intense, and special care must be taken when using this calculation method, as errors may sometimes overwhelm the actual results. Therefore, the display differential format is generally less used in bright full-flow calculations.

[0159] for Figure 12 As shown in the hydropower station with a diversion tunnel combined with a tailra...

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Abstract

The invention discloses a non-steady flow simulating method for a pipe network system. The invention provides the non-steady flow simulating method which solves a non-steady flow by combining an obvious format and a hidden format and is suitable for complex pipe network systems. The method is based on a chasing method, three methods of a basic solution, a local iteration solution and a layered solution are provided for meeting the arraying modes of different pipe network systems and the dividing features of obvious and hidden format pipelines, and the hidden pipe network matrix equitation is solved by adopting a simple method. The non-steady flow simulating method for the pipe network system is suitable for the pressure pipeline systems and pressure-free drainage systems in large-scale river network non-steady flows in the transition process of a hydropower station as well as the non-steady flow simulation of an obvious full mixed flow system, and the non-steady flow simulating precision can be improved.

Description

technical field [0001] The invention belongs to the field of unsteady flow calculation of a pipe network system, in particular to a method for simulating unsteady flow of a pipe network system. Background technique [0002] The accuracy of the simulation of the transition process of the hydropower station largely affects the design of the structure and size of the hydroelectric power generation system, and has important guiding significance for the safe and stable operation of the hydropower station. Its numerical simulation involves the mutual coupling of three aspects of water, electromechanical, and the calculation accuracy of one aspect directly affects the calculation results of other aspects. However, for the water system in the water diversion power generation system, it is inevitable to contain pipelines such as draft pipes, gradual transition sections, long connecting pipes, short pipes, and open channels of the surge chamber that are not suitable for calculation by...

Claims

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Application Information

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IPC IPC(8): G06F19/00
Inventor 杨建东王超杨桀彬
Owner WUHAN UNIV
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