This report summarizes some NASA Lewis (i.e., government owned) computer codes capable of being used for airbreathing propulsion system studies to determine the design geometry and to predict the design/off-design performance of compressors and turbines. 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 analyses. Losses are provided by empirical methods. Both axial-flow and radial-flow configurations are included.

https://ntrs.nasa.gov/api/citations/19960008691/downloads/19960008691.pdf

Design geometry and design/off-design performance computer codes for compressors and turbines

A brief description of the physical flow phenomena in a blade row that creates losses
in an axial gas turbine and correlations to estimate these losses in a mean line
calculation are given. Investigation and comparison of the loss correlations for 1D
mean line calculation between the in-house program (CTC) used at Siemens and loss
correlations present in the open literature were made. The investigation is primarily
focused on the problems associated with modeling off-design effects on profile and
secondary losses, and the effect of tip leakage losses at all loads. For the off-design
condition both positive and negative flow incidence were covered with internal tests
and numerical 2D investigations. The increase in blade losses at high outlet Mach
number and how it is related to the shape of the suction surface for a blade profile was
investigated with numerical 2D simulation.
The results for the loss models are validated against previous done internal gas turbine
test runs at Siemens, external cascade tests and numerical 2D simulations.
The overall conclusions are that the in-house program (CTC) shows good prediction
ability for the off-design down to the state where the turbine reaches turn-up mode.
But some questions about CTC’s distribution between profile and secondary losses
are discussed.
For the tip leakage loss it was highlighted that CTC shows a somewhat low loss for a
constant clearance and also a rather low increase with relative clearance change. A
limitation in the prediction ability because the absence of some believed important
parameter was also seen and an alternative model was suggested for unshrouded
blades.
It is clear that there for most blade designs is seen a sudden increase in the blade
losses at an outlet Mach number in the region of 0.9. But no obvious relations to
which blade parameters that determine the absolute increase were found

/pdf/investigation-of-losses-prediction-methods-in-1d-for-axial-3263g6m6du.pdf

Investigation of Losses Prediction Methods in 1D for Axial Gas Turbines

A cursory review is presented of some of the recent work that has been done in turbine aerodynamic research at NASA-Lewis Research Center. Topics discussed include the aerodynamic effect of turbine coolant, high work-factor (ratio of stage work to square of blade speed) turbines, and computer methods for turbine design and performance prediction. An extensive bibliography is included. Experimental cooled-turbine aerodynamics programs using two-dimensional cascades, full annular cascades, and cold rotating turbine stage tests are discussed with some typical results presented. Analytically predicted results for cooled blade performance are compared to experimental results. The problems and some of the current programs associated with the use of very high work factors for fan-drive turbines of high-bypass-ratio engines are discussed. Turbines currently being investigated make use of advanced blading concepts designed to maintain high efficiency under conditions of high aerodynamic loading. Computer programs have been developed for turbine design-point performance, off-design performance, supersonic blade profile design, and the calculation of channel velocities for subsonic and transonic flow fields. The use of these programs for the design and analysis of axial and radial turbines is discussed.

New technology in turbine aerodynamics.

Computer code TD2 computes design point velocity diagrams and performance for multistage, multishaft, cooled or uncooled, axial flow turbines. This streamline analysis code was recently modified to upgrade modeling related to turbine cooling and to the internal loss correlation. These modifications are presented in this report along with descriptions of the code's expanded input and output. This report serves as the users manual for the upgraded code, which is named TD2-2.

/pdf/users-manual-and-modeling-improvements-for-axial-turbine-44uhyh4uqu.pdf

Users manual and modeling improvements for axial turbine design and performance computer code TD2-2

In this paper, preliminary studies on two turbine engine applications relevant to the tilt-rotor rotary wing aircraft are performed. The first case-study is the application of variable pitch turbine for the turbine performance improvement when operating at a substantially lower shaft speed. The calculations are made on the 75 percent speed and the 50 percent speed of operations. Our results indicate that with the use of the variable pitch turbines, a nominal (3 percent (probable) to 5 percent (hypothetical)) efficiency improvement at the 75 percent speed, and a notable (6 percent (probable) to 12 percent (hypothetical)) efficiency improvement at the 50 percent speed, without sacrificing the turbine power productions, are achievable if the technical difficulty of turning the turbine vanes and blades can be circumvented. The second casestudy is the contingency turbine power generation for the tilt-rotor aircraft in the One Engine Inoperative (OEI) scenario. For this study, calculations are performed on two promising methods: throttle push and steam injection. By isolating the power turbine and limiting its air mass flow rate to be no more than the air flow intake of the take-off operation, while increasing the turbine inlet total temperature (simulating the throttle push) or increasing the air-steam mixture flow rate (simulating the steam injection condition), our results show that an amount of 30 to 45 percent extra power, to the nominal take-off power, can be generated by either of the two methods. The methods of approach, the results, and discussions of these studies are presented in this paper.

https://ntrs.nasa.gov/api/citations/20090022130/downloads/20090022130.pdf

Preliminary Axial Flow Turbine Design and Off-Design Performance Analysis Methods for Rotary Wing Aircraft Engines

Stream-filament analysis procedure and correlation of total pressure loss coefficients to form basis of computer program to investigate design point performance of axial turbines

/pdf/analysis-of-geometry-and-design-point-performance-of-axial-2xzzq2kt2r.pdf

Analysis of geometry and design point performance of axial flow turbines. 1 - Development of the analysis method and the loss coefficient correlation

/pdf/analysis-of-geometry-and-design-point-performance-of-axial-3l3xo9wcgn.pdf

Analysis of geometry and design-point performance of axial-flow turbines using specified meridional velocity gradients

Smith correlation of turbine stage efficiency for relating achievable efficiency to stage loading and flow factors used for total pressure loss coefficient data

Correlations of turbine blade total-pressure- loss coefficients derived from achievable stage efficiency data.

Computer program for design of axial flow turbines with velocity distribution gradients at stator and rotor exits

/pdf/the-analysis-of-geometry-and-design-point-performance-of-5d28gcmhae.pdf

A. F. Carter

Papers

Analysis of geometry and design point performance of axial flow turbines. 1 - Development of the analysis method and the loss coefficient correlation

Analysis of geometry and design-point performance of axial-flow turbines using specified meridional velocity gradients

Correlations of turbine blade total-pressure- loss coefficients derived from achievable stage efficiency data.

The analysis of geometry and design-point performance of axial-flow turbines using specified meridional velocity gradients. Part 2 - Design examples