| Pressurized fluid transient systems are often seen in hydraulic and hydropower engineering, water and waste water engineering, hydraulic pressure systems and fluid (water , oil, gas. etc.) transport systems. After the theory of water hammer was present at the beginning of 20* century, the study of pressurized fluid transients (PFT) experienced the stages of rigid water column theory, graphical method and numerical analysis. Now the analysis ability of PFT is very strong. The forward problems in various pressurized fluid transient systems are solvable hi general. But people are not satisfied with these achievements and hope that they can identify, design and control PFT by all means, that is to solve the inverse problems of PFT. A pressurized fluid transient system is considered to work well only If it not only runs safely and reliably, but also completes the change of operating mode quickly and stably. To meet these requests, the system must be identified effectively and be designed and controlled reasonably. This is the strong drive to study the inverse problems of PFT.In this paper, the frame of the theory of inverse problem of PFT is preliminarily formed. In view of the control of PFT, three kinds of the inverse problems of PFT are studied systematically, including inverse problems of whole controllability of system, the control hi a specified time and the control with a specified pressure. The main contents are as follows:1. The definitions of the forward and the inverse problem of PFT are proposed and the latter is classified according to the aim of solution. The main methods to solve the inverse problems of PFT are summarized, forming the frame of the theory of the inverse problems of PFT. In the meantime, it is pointed out that the inverse problems are often improper. To solve the improper problems, it is effective to change the inverse problems into the problems of optimization and optimal control. To solve the inverse problems is to optimize and optimal control the systems essentially.2. The definition of the global controllability of systems and the concept of the "beginning subsystem" are proposed. The method to determine the global controllability of pressurized fluid transient systems is presented. The methods to make globally uncontrollable systems globally controllable are pointed out.3. According to the definition of the inverse problem of control in a specified time, the mathematical model is established. It is pointed out that the attached conditions must be added in the model to make the inverse problem solvable. But this inverse problem is still improper. Adding other control aim (restricted condition) can make the inverse problem proper. The optimal mathematical model, hi which the control aim is to make the peek value of water hammer smallest, is set up for the application in hydraulic and hydropower engineering. For the beginning subsystem of a PFT system, the optimalmethod combining with the method of characteristics(MOC) with calculation proceeding in spatial direction is used to solve the inverse problem. For other pipelines, the MOC with calculation proceeding in spatial direction is used to solve the inverse problem.4. Based on whether the fluid in the system is in steady state immediately after regulating, the control Inverse problem with specified pressure is classified into the first class problem and the second problem.The mathematical model of the first class control inverse problem with specified pressure is established, which is improper. To solve this improper problem, the optimal mathematical model, in which the control aim is to make the regulating time shortest, is set up. Taking into account the complexity of PFT systems and the applicability of solution method, the ideal method is the optimal method combing with the MOC.The mathematical model is set up, based on the definition, for the second class control inverse problem with specified pressure. The optimal mathematical model is established, hi which the control aim is to make the regulating ti...
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