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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  • Claims
  • Application Information

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Problems solved by technology

[0008] Based on the above analysis, the existing simulation methods are used for unstea

Method used

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  • Non-steady flow simulating method for pipe network system
  • Non-steady flow simulating method for pipe network system
  • Non-steady flow simulating method for pipe network system

Examples

Experimental program
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Example Embodiment

[0131] Example 1

[0132] In the pipeline system, the implicit difference method is used to solve non-prismatic pipes, and the explicit difference method is used to solve other pipelines.

[0133] The draft tube is a non-prismatic pipeline whose pressure value is an important adjustment parameter during the transition process of a hydropower station. The draft tube is a variable cross-section flow passage. Excessive negative pressure in the draft tube of a hydropower station will cause the steel lining to instability , 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 shock pressure causes cavitation and vibration of the turbine runner. Turbine flow and torque characteristics are generally determined by the comprehensive characteristic curves of the runner model under stable conditions. These characteristic curves do not include the influence of the inertia of the water flow under the u...

Example Embodiment

[0134] Example 2

[0135] In the pipeline system, the surge tank is solved by the implicit difference method, and other pipelines are solved by the explicit difference method.

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

[0137] see Picture 10 The surge chamber and pipeline shown, the upstream and downstream pipelines of the surge chamber are solved by the characteristic line method, and the surge chamber is solved after being discretized by the Preissmann four-point implicit scheme.

[0138] The surge chamber is divided into n sections, and the last section n is the free water surface. When the grid is determined, the head H n It is known that the supplementary equation for the first section...

Example Embodiment

[0156] Example 3

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

[0158] The basic equation of open channel unsteady flow can be solved using explicit and implicit difference schemes. The explicit difference scheme is mainly the characteristic line method. One of the solutions is to satisfy the Courant condition, the time step is limited, and the numerical stability is difficult to guarantee. ; Second, interpolation is needed, and interpolation errors are difficult to avoid, especially when the transient process is fierce. Use this calculation method with special care, and the errors sometimes overwhelm the actual results. Therefore, the display difference format is generally less used in the calculation of full flow.

[0159] for Picture 12 As shown in the hydropower station with diversion tunnel combined with tailrace tunnel or tailrace tunnel with ...

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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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