PURPOSE AND SCOPE OF ESDUpac A9446 and VIEWpac 9446A Item No. 94046 provides details of a Fortran computer program@ ESDUpac A9446@ for use in the design and performance evaluation of ejectors and jet pumps in which the working fluids are gases. A user-friendly version@ referred to as VIEWpac 9446A@ is also available@ and is described in Section 4 ESDUpac A9446 provides the following design and performance prediction procedures. (i) Quick Design Procedure. Given a selection of entry and required exit pressures@ temperatures@ mass flow rates and dimensions@ the program will calculate primary nozzle and exit dimensions@ using empirical data for steam-air ejectors. Note that the scope of the Quick Design Method is restricted to ejectors with constant area mixing and air as the secondary fluid. (ii) Detailed Design Procedure. Given a selection of entry and required exit pressures@ temperatures@ mass flow rates@ dimensions and loss factors as well as four user defined constraints on the flow conditions@ the program will calculate primary nozzle and exit dimensions and flow conditions throughout the ejector using the procedure outlined in Section A1 of Appendix A. (iii) Performance Prediction Calculation. Given the ejector dimensions@ loss factors and a range of flow conditions at the entry@ the program will calculate the outlet conditions and the flow conditions throughout the ejector@ using the procedure outlined in Section A13 of Appendix A. Section 5 describes the required input data. Section 6 provides notes on the design and operation of steam/gas ejectors. A number of examples that illustrate the use of the program are presented in Section 7. The full analysis for the computer program appears in Appendix A. In many ejectors@ the secondary inlet conditions are set by existing upstream pipework. In the design procedure@ the program optimises for the shortest mixing duct length for complete mixing of the primary and secondary fluids and for the highest efficiency. The program allows a design requirement for a particular pressure and/or mass flow characteristic at the exit of the ejector to be met. The ejector design procedures determine performance at the primary nozzle 'on-design' point. There are a number of situations in which this approach will be inadequate. The ejector may be required to operate over a range of primary pressures or secondary Mach numbers@ in which case estimates of 'off-design' performance must be sought. Performance prediction is also necessary if an existing plant item@ with all physical dimensions known@ needs to be assessed for a particular application. The performance prediction procedure calculates the flow conditions in an ejector of known physical dimensions. The calculation procedure presented in Appendix A is applicable to non-reacting gases that can be modelled as ideal and to ejectors with mixing ducts of circular (either cylindrical or conical) section. The methods are based on the equations of continuity and of momentum and energy conservation.