|
The gas-turbine powers and power plants (GTP) are widely used in diversified industries, such as the power engineering, aircraft and transport. In previous years the main direction of their development was increasing the parameters of a thermodynamic cycle: gas temperature in front of a turbine and pressure ratio. However, in the last few years the possibility of increasing the gas-turbine plant efficiency at the expense of such parameters growth has diminished considerably because the thermodynamic cycle parameters came nearly to their theoretical limit. Most clearly it can be seen on an air gas-turbine engines example, in which the gas temperature level in front of the turbine has reached 1800 C. In these conditions, the main development trend for GTP is to increase the units efficiency in all operational modes. One way out is the complex nonconventional scheme GTP designing. in which there are additional units and channels switching the flow of a propulsive mass in different operational modes. The gas-turbine engines which have a high performance at small subsonic, and at large supersonic flying speeds are developed in aviation. Such GTP is called a variable-cycle engines (VCE). Among them, there are not only electric generator driving GTP, but also steam heating GTP for building heating system, and compressed air generators. Since the load distribution in all these directions can change during the work, such power GTP need to have a rather complicated scheme. As an example, let us consider the project of a variable-cycle engine for a perspective supersonic airplane, a VCE with a common fan turbine. When designing such gas-turbine engines, the significant problem is the compatibility of all the units power characteristics at large quantity of structurally geometrical limitations on them. The units must have not only high efficiency values, but also to be matched with each other on power parameters: power, consumption of a propulsive mass, rotational speeds, and also on design and geometrical parameters -diameters, number of stages etc. For this purpose, the program complex of a computer-assisted design of complex scheme GTP is developed, EACAD. These programs for modeling different engines with the purpose to ensure the compatability of all the units parameters in the most of Designer Bureaues are made anew for each particular scheme or for the several similar schemes. The EACAD developers have given large attention to the possibility to design and to calculate the schemes of gas-turbine engines without any limitations on their structure. EACAD allows to make the GTP scheme, to determine the main GTP parameters (thrust, power, specific ftiel consumption etc.), and also to determine the main geometrical sizes (provisional length, area of cross sections). The engine scheme is injected into a printer.
|
