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Ejectors and Jet Pumps

Ejectors and jet pumps: computer program for design and performance for compressible gas flow. (92042)

ESDU 92042 introduces a Fortran program (available as ESDUpac A9242) for the design or performance assessment of ejectors (or jet pumps) in which the primary and secondary flows may be of the same or of different gases. It uses two approaches to design. The quick design method is based on an analysis of experimental data for single-nozzle designs and, given a minimum of input (selection of entry and required exit pressures, temperatures, mass flow rate and dimensions), will calculate primary nozzle and exit dimensions. The detailed design method, based on one-dimensional flow equations that are detailed, applies also to multi- and annular-nozzle designs. In addition to the input for the quick method, it requires loss factors (in the primary and secondary nozzles, mixing duct and contraction or diffuser) and acceptable maximum design values for four parameters, but will calculate flow conditions throughout the ejector. The performance assessment method for an existing design, also based on the one-dimensional flow equations, calculates conditions throughout the ejector and at exit given the geometry, loss factors and a range of entry conditions. The use of the three methods is illustrated in a worked example.

Keywords: COMPRESSIBLE, DESIGN, EJECTOR, FLOW, GAS, JET, OPTIMISATION, OPTIMIZATION, PERFORMANCE, PROGRAM, PUMP

Ejectors and jet pumps: computer program for design and performance for liquid flow. (93022)

ESDU 93022 introduces a Fortran program (ESDUpac A9322) for ejectors in which the primary and secondary flows are of non-reacting miscible liquids. Inlet conditions for both primary and secondary flows can be either constant pressure or provided by a pump. In the latter case it is assumed that the head can be expressed as a quadratic in pump speed and flow rate. Two procedures are provided: a Design Procedure and Performance Prediction. For the first the input is a selection of entry and required exit pressures and flow rates, together with estimates of loss coefficients in the primary and secondary nozzles, mixing duct and diffuser. The program will optimise the ejector, calculating the primary nozzle, secondary inlet and ejector exit dimensions. For the second case, the ejector dimensions are input together with the loss factors again and a range of entry flow conditions and the program will calculate flow conditions throughout the ejector and at exit. The equations on which the program is based are fully specified, the input format required is set out in clear tables, and two worked examples illustrate the use of both procedures. The program is provided in a complied form as ESDUpac A9322 and is incorporated into VIEWpac 9322A.

Keywords: DESIGN, EJECTOR, JET, LIQUID, OPTIMISATION, OPTIMIZATION, PERFORMANCE, PROGRAM, PUMP

Ejectors and jet pumps. Design and performance for incompressible liquid flow. (85032)

ESDU 85032 provides procedures for the design and performance prediction of ejectors and jet pumps where both the primary and secondary streams are liquid.The first procedure obtains an optimum design for a required duty, and the second predicts performance of an existing ejector so as to study the effect of minor changes. The methods are based on one-dimensional flow theory, supplemented by empirical correlations for the losses within the nozzles and mixing duct, and the equations are detailed. Extensive design charts are included, and flowcharts guide the user through the simple step-by-step procedures which are illustrated by three detailed practical worked examples. Guidance is provided on the use of annular- or multi-nozzle arrangements, various mechanical aspects, and on the performance prediction of ejectors for gas flow, and on the avoidance of cavitation.See ESDU 93022 for a Fortran program of the calculation methods.

Keywords: DESIGN, EJECTOR, JET, LIQUID, OPTIMISATION, OPTIMIZATION, PERFORMANCE, PUMP

Ejectors and jet pumps. Design for steam driven flow. (86030)

ESDU 86030 gives step-by-step calculation procedures, based on performance charts, for the optimum design of steam/liquid and steam/gas ejectors. For steam/gas ejectors the data are derived from a wide range of experimental results, but for steam/liquid ejectors there were insufficient data and a theoretical analysis was used. For steam/liquid ejectors a performance prediction method is included that allows off-design behaviour to be estimated. Practical examples using the methods illustrate their application. Mechanical design considerations for the components (primary nozzle, mixing chamber, contraction or diffuser) are described, and the use of annular or multi-nozzle arrangements is considered. Application by multi-staging is discussed. Operating problems in start-up or shut-down are introduced, together with consideration of instability and noise. Limits imposed by the onset of cavitation and vapour binding are outlined for steam/liquid use. ESDU 94046 introduces a program, ESDUpac A9446, that implements the method outlined here.

Keywords: DESIGN, EJECTOR, GAS, JET, LIQUID, OPTIMISATION, OPTIMIZATION, PERFORMANCE, PUMP, STEAM

Ejectors and jet pumps: computer program for design and performance for steam/gas flow. (94046)

ESDU 94046 introduces a Fortran program (ESDUpac A9446) for ejectors in which the primary and secondary flows are non-reacting gases that can be modelled as real. Three procedures are provided: a Quick Design Procedure, a Detailed Design Procedure and Performance Prediction. The first is based on experimental data obtained for steam ejectors pumping air at 20 degrees C. If other gases are handled the secondary mass flow rate is converted by the program to an equivalent rate based on the molar mass of the secondary gas. For the second the input is a selection of entry and required exit pressures and flow rates, together with estimates of loss coefficients in the primary and secondary nozzles, mixing duct and diffuser. The program will optimise the ejector, calculating the primary nozzle and exit dimensions, and flow conditions throughout. For the third case, the ejector dimensions are input together with the loss factors again and a range of entry flow conditions and the program will calculate flow conditions throughout the ejector and at exit. The equations on which the program is based are fully specified, the input format required is set out in clear tables, and three worked examples illustrate the use of the procedures. Notes are provided on the mechanical design of steam/gas ejectors including the use of multi-stage units and annular- or multi-nozzles. Possible operating problems are discussed.

Keywords: DESIGN, EJECTOR, GAS, JET, OPTIMISATION, OPTIMIZATION, PERFORMANCE, PROGRAM, PUMP, STEAM