Introduction
The following descriptions are excerpted from open-literature reports and are intended to provide information to our customers in the user community. No proprietary or critical agency information is disclosed. Specifically, the text for this page is taken from Arthur Glassman's NASA CR-198433.

This page summarizes several NASA Glenn government-owned computer codes used by this organization for determination of design geometry and the prediction of design- and off-design performance of compressors and turbines. Not all such codes available at NASA Glenn are presented, but those included provide conceptual, preliminary design capabilities required for airbreathing propulsion studies. Both axial flow and radial flow configurations can be analyzed.

These are not CFD codes. Velocity diagram energy and continuity computations are performed fore and aft of the blade rows using meanline, spanline, or streamline analysis techniques. Losses are provided by empirical correlations or by simple physics with empirical coefficients. These programs run very fast; answers are obtained in seconds on a Unix workstation, and many of the codes run on a Windows PC. Most of these codes are quite robust in terms of running to completion. They provide good "ballpark" numbers for preliminary analysis and screening.

It must be remembered that these codes are merely tools to be used by the analyst. They cannot differentiate between acceptable and unacceptable design or performance solutions as long as these solutions are mathematically feasible. The user must contribute some knowledge to the process of selecting a best, or even an acceptable, design.

Compressors

CSPAN - Compressor SPANline Design Code
CSPAN is a spanline analysis code that uses isentropic simple radial equilibrium to determine the flowpath and efficiency either for a given number of stages or for a given overall pressure ratio. There is only one calculation station between the blade rows. Hub radius is determined from the inlet radius ratio and the input tip radius distribution; this simplifies the continuity solution. Stage energy addition is controlled by specifying maximum allowable values for several aerodynamic design parameters: rotor-tip and stator-hub diffusion factors, rotor-hub turning, and stator-inlet-hub Mach number. There are two internal loss models: (1) stage and rotor polytropic efficiencies as functions of stage pressure ratio, and (2) blade row pressure loss coefficients as a function of meanline diffusion, endwall clearance, and shocks. Correlations are included for the calculation of endwall blockage (optional) and for the prediction of stall margin.

CSPAN input includes the design requirements of flow rate and overall pressure ratio (or maximum number of stages). First rotor tip speed, inlet radius ratio, tip diameter variation, and aerodynamic design limits can be fixed or varied for parametric studies. Default values are available for the aerodynamic limits are well as for solidities, aspect ratios, and stage reaction distribution. The output includes the hub radii, diagram velocities and angles, blading geometry, stage and overall efficiencies, and stall margin.

CCD - Centrifugal Compressor Design (aka QUIK)
CCD provides a rapid preliminary assessment of design geometry and design point performance of centrifugal compressors with radial or swept rotor blades. The analysis is based on a one-dimensional meanline flow model with correlations for the following losses: inlet guide vane, rotor shock, incidence, clearance, blade loading, skin friction, disk friction, and recirculation, vaneless diffuser skin friction, and vaned diffuser friction loading. Free vortex prewhirl can be specified, and simple radial equilibrium is used to provide the radial gradients at the rotor inlet. Splitter blades are allowed. Design point efficiency and stall margin (determined by the off-design code), whose requirements are usually at odds with each other are largely determined by impeller inlet flow angle and diffuser throat area. Choke margins are used to control these parameters. CCD can operate in design mode with input flow and pressure ratio or in analysis mode with input geometry.

For design mode, the program input includes mass flow rate and pressure ratio. The key design variables are inlet flow angle and velocity, rotor rotational or specific speed, exit blade angle and reaction, and amount of diffusion in the vaned (or pipe) diffuser. The output presents the computed design geometry, efficiency, and local flow parameters. A complete input file for the CCOD off design code can be written by the CCD design code.

CCOD - Centrifugal Compressor Off-Design (aka CCODP)
CCOD is a one-dimensional meanline code for the off design performance of centrifugal compressors with radial or swept rotor blades. The losses are the same as enumerated above for CCD, as are the capabilities to handle inlet prewhirl and splitter blades. Stall prediction is based on pressure recovery from impeller exit to diffuser incidence. Choke may occur at the impeller inducer (i.e., inlet), the impeller exit, or the diffuser throat.

CCOD input includes the flowpath dimensions and the blading angles. The CCD design code can prepare a CCOD input file. Calculations are performed for the desired speeds from low to high flow subject to stall and choke limitations. Each speed line can be run automatically from stall to choke, or just parts of the speed line can be run by specifying inlet velocity ratio limits. Pressure ratio and efficiency are output as functions of flow and speed, and detailed velocity diagram output can be optionally presented. A map file for subsequent cycle analysis can also be obtained.

CMGEN - Compressor Map GENeration
CMGEN uses parametric relations to generate compressor performance maps. The basic inputs are pressure ratio, inlet corrected flow per unit area, and stall margin. A map file for subsequent cycle analysis can also be obtained.

MODFAN - MODular FAN Map Generation
MODFAN uses parametric relations to generate fan performance maps. The basic inputs are pressure ratio, inlet corrected flow per unit area, and stall margin. A map file for subsequent cycle analysis can also be obtained.

Turbines

TURBAN - TURbine ANalysis
TURBAN is a meanline design code based on simplifying assumptions that limit the generality of the analysis but result in a very rapid calculation that needs a minimum of input. This is not the typical blade row by blade row bookkeeping of mass and energy. The stage velocity diagrams are either all similar (thereby having the same work factor) or are determined from an input stage work split. All stages have the same stator exit angle. Stage by stage tailoring of the velocity diagrams is not allowed. Only inlet and exit diameters are specified, and the stage mean diameters vary linearly. The loss model is a simple viscous type related to the velocity diagrams. A simple blading model provides solidities and stagger angles. Turbine coolant flows and temperatures can be specified.

TURBAN input includes flow rate, rotative speed, and power or pressure ratio. Options are provided for varying number of stages, diameter (mean or hub or tip), stator exit angle or exit radius ratio, and reaction, loading, diagram type, and/or work split. The output presents annulus dimensions, diagram velocities and angles, blading geometries, and efficiencies.

TD2 - Turbine Design 2
TD2 performs a streamline analysis that uses meridional velocity gradients to control the radial distribution of flow and work for the design of multistage, multishaft, cooled or uncooled, axial flow turbines. Using a specified meridional gradient rather than a specified tangential velocity gradient assures an acceptable flow distribution, thus avoiding a major cause of program failure. Streamline slope and curvature are included in the radial equilibrium. The flowpath radii are fully specified. The velocity diagrams for each stage can be individually controlled. An internal loss correlation determines blade row total pressure loss coefficients along the streamlines.

TD2 input includes primary and coolant flows, temperatures, pressure, rotative speed, and power. Design parameters that can be varied include number of stages, hub and tip radii streamwise distribution, stage work split, and stage velocity diagram optional controls such as stator exit tangential velocity (mean), stator exit angle radial distribution, and blade row exit meridional velocity distributions. The output presents the detailed distributions of temperatures, pressures, velocities, angles and stage overall efficiencies.

TD2 provides the capability to tailor/control the stagewise as well as the radial variations of the velocity diagram characteristics, but requires considerable more input that does TURBAN. Any turbine of known flowpath and velocity diagram design can be modeled. This capability allows the user to go beyond the conceptual study into a preliminary design and also to evaluate specific configurations. Due to the need to satisfy many constraints at once (continuity within the given flowpath, stage work, radial equilibrium, the blade element loss correlation, radial distribution of stator exit angle or meridional velocity, and radial distribution rotor exit work or meridional velocity gradient), it is not unusual to find combinations of inputs for which no solutions exists. This type of failure can be minimized by maintaining the radial distributions close to free vortex values and allowing ample flow area.

AXOD - (Axial Turbine Off-Design Analysis)
AXOD is a spanline (which can be reduced to a meanline as a lower limit) analysis code with simple radial equilibrium to compute the flow and efficiency of mutistage axial flow turbine as functions of speed and pressure ratio. Although this is basically a spanline analysis, interpolation procedures are used to account for flow entering and leaving constant sectors within blade rows. Each speed line can be rum from low pressure up to the maximum pressure ratio of limit load. The loss model is made up of blade row inlet losses, blade row losses, and stage test losses. Coefficients are selected to match known design point performance, and the internal model provides the off design performance. Coolant flow addition is allowed.

AXOD can also do a design calculation, but there is no built-in design point loss model. As with the off-design calculation, the efficiency at the design point must be known so that appropriate loss coefficients can be selected. Also, stage work is specified by rotor inlet and exit tangential momentums which are not convenient because their relationship to the more familiar values of blading angle and reaction is not readily apparent.

AXOD input includes the blade row inlet and exit hub and tip radii and blading angles to define the turbine geometry. For each speed, first stator total-to-static pressure ratio is varied between the specified limits at specified increments to compute points along the speed line. The maximum allowable overall pressure ratio is that at limit load, defined as an axial Mach number of unity at the turbine exit. The output, available at three levels of detail, includes total and static efficiencies and pressure ratios, both overall and stage actual and corrected performance parameters, and flow velocities and angles at all calculation locations. A map file for subsequent cycle analysis can also be obtained.

RTD - Radial Turbine Design Code
RTD executes a conceptual design for a single stage radial inflow turbine having optimum incidence entering the rotor. A meanline analysis is performed across the stator and into the rotor, where the radii are constant over the blade span; at the rotor exit, where there are significant radial gradients, a spanline analysis is used. In the case of the radial inflow turbine, where the flow is assumed uniform across the rotor inlet, the spanline analysis does not introduce erros due to shifting of flow in and out of sectors. The analysis can account for stator endwall clearance flow that would occur with pivoting stators and for swept rotor blades. Splitter blades are allowed. The loss model includes stator and rotor friction and trailing edge losses, vaneless space loss, disk friction loss, and rotor exit clearance loss.

RTD input design requirements are power, flow rate, and rotative speed. The design variables include stator exit angle, rotor blade inlet angle, rotor exit tip and hub radius ratios, and rotor swirl distribution, The output presents the computed rotor tip diameter, all blade row inlet and exit dimensions, diagram velocities and angles, and total and static efficiencies. RTD can write an input file for the RTOD off design code.

RTOD - Radial Turbine Off-Design Code
RTOD predicts the flow rate and efficiency of a single stage radial inflow turbine as functions of pressure ratio, speed, and stator setting. The rotor blades can be either radial or swept, and splitters can be included. As with RTD, the stator inlet and exit and rotor inlet flows are modeled with a meanline analysis, while a sector analysis (i.e., spanline) is used at the rotor exit. Clearance flow is included when a pivoting stator is used to provide variable area. The loss model includes stator viscous and trailing edge losses, a vaneless space loss, and rotor incidence, viscous trailing edge clearance, and disk friction losses.

The RTOD input includes the flowpath dimensions and the blading angles. A complete RTOD input file can be written by the RTD design code. Performance is calculated for constant speed lines from low to high pressure ratio, with limit load as an upper limit. Output can be obtained at different levels of detail from overall performance only (pressure ratio, flow rate, total and static efficiencies, etc.) to absolute and relative state conditions, velocities. A map file for subsequent cycle analysis can also be obtained.

PART - PARameteric Turbine Map Generation Code
PART uses parametric relations to generate turbine performance maps. The basic inputs are pressure ratio and inlet corrected flow per unit area. A map file for subsequent cycle analysis can also be obtained.

+Turbomachinery Analysis Codes
Code repository (Sorry, NASA only).