The objective of the Aerothermodynamic Loads Definition Study is to develop methods of accurately predicting the operating environment in advanced Earth-to-Orbit (ETO) propulsion systems, such as the Space Shuttle Main Engine (SSME) powerhead. Development of time averaged and time dependent three dimensional viscous computer codes as well as experimental verification and engine diagnostic testing are considered to be essential in achieving that objective. Time-averaged, nonsteady, and transient operating loads must all be well defined in order to accurately predict powerhead life. Described here is work in unsteady heat flow analysis, improved modeling of preburner flow, turbulence modeling for turbomachinery, computation of three dimensional flow with heat transfer, and unsteady viscous multi-blade row turbine analysis

Gaugler, Raymond E.

English

NASA Technical Reports Server

N93-31583
OVERVIEW OF AEROTHERMODYNAMIC LOADS DEFINITION STUDY
Raymond E. Gaugler
NASA Lewis Research Center
Cleveland, Ohio 44135
INTRODUCTION
For a number of years now, NASA has been conducting the Advanced Earth-to-
Orbit (AETO) Propulsion Technology Program, now part of the Civil Space
Technology Initiative (CSTI) Program. The program objective is to provide the
knowledge, understanding, and design methodology that will allow the
development of advanced earth-to-orbit propulsion systems with high
performance, extended service life, automated operations, and diagnostics for
in-flight health monitoring. This program supports both current and future
engine and vehicle developments. The technology needs of the current Space
Shuttle Main Engine (SSME) have thus far provided the main focus for the AETO
efforts. Organizationally, the program has been divided into technology
working groups made up of people from both the Marshall Space Flight Center
and the Lewis Research Center. The focus of this report is the Lewis effort
under the Fluid and Gas Dynamics working group, the Aerothermodynamic Loads
Definition Study.
The objective of the Aerothermodynamic Loads Definition Study is to develop
methods to more accurately predict the operating environment in advanced ETO
propulsion systems, such as the Space Shuttle Main Engine (SSME) powerhead.
Development of time averaged and time-dependent, three dimensional viscous
computer codes as well as experimental verification and engine diagnostic
testing are considered to be essential in achieving that objective. Time-
averaged, nonsteady, and transient operating loads must all be well defined in
order to accurately predict powerhead life.
The approach taken under this study consists of two parts: I) to
modify/apply/disseminate existing computational fluid dynamics (CFD) tools in
response to current needs, and 2) to develop new technology that will enable
more accurate computation of the time-averaged and unsteady aerothermodynamic
loads in reusable space propulsion systems. The new technology development
effort is further divided into three parts: I) new computer code
development, 2) experiments to provide data for physical models required by
the codes, and 3) experiments to provide data for validating the codes. With
the more accurate aerothermodynamic loads predictions providing boundary
conditions to improve structural and fatigue life analyses, the goal of
improved durability will be met.
The Aerothermodynamic Loads Definition Study was begun in October, 1983. The
initial effort involved the use of existing CFD tools to analyze problems in
the SSME fuel and oxidizer turbopump turbines, the fuel turbine turnaround
duct, the fuel side preburner and the main injector LOX posts. Results of
those efforts have been presented previously and will not be discussed here.
What follows in a description of the currently active tasks and their status.
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https://ntrs.nasa.gov/search.jsp?R=19930022394 2020-03-17T05:07:31+00:00Z
H4(a). UNSTEADY VISCOUS MULTI-BLADE-ROW TURBINE ANALYSIS
In this task, the objective is to develop a numerical simulation capability
for unsteady viscous flow and heat transfer in interacting turbine blade rows.
The numerical simulation of unsteady viscous flows in turbines can provide
much useful information on the factors effecting performance and life of these
requires a means of reducing the three-dimensional, nonperiodic, multi-row
problem remains intractable, a quasi-three dimensional treatment can be used
to analyze much of the flow over the midspan portion of the turbine passage.
Existing turbulence models are being modified to incorporate known relevant
unsteady flow effects. These models will be developed using unsteady boundary
layer codes and then implemented in a highly efficient quasi 3D rotor-stator
interaction code previously developed under this task. The resulting analysis
will then be tested against data obtained from a low-speed turbine under task
H4(e).
H4(b). Computation of 3D FLOW WITH HEAT TRANSFER
In this task, the objective is to develop an accurate, efficient numerical
analysis of steady 3D viscous flow and heat transfer in turbine blade rows.
The approach being taken is to modify a 3D viscous turbomachinery code (RVC3D)
to include an advanced turbulence model and increased resolution of near-wall
gradients and to validate and upgrade the code by application to suitable 3D
data sets. Figure ] shows a preliminary comparison of experiment and computed
results of endwall heat transfer using this code.
H4(e). 3D STATOR-ROTOR BLADE FLOW EXPERIMENTS
The objective of this task is to investigate the steady and unsteady 3D
viscous flow field in an axial turbine stage, including stator-rotor
interaction, mixing effects, blade and endwall boundary layers, and
temperature gradient effects on secondary flow development. This work is
being done in the Pennsylvania State University Axial Flow Turbine Research
Facility.
A progress report will be presented later in this session.
H4(m). TURBULENCE MODELING FOR PROTEUS TURBOMACHINERY APPLICATION
The objective of this task is to develop the capability to predict turbulent
flow losses and heat transfer in turbines typical of ETO propulsion systems
using a 3D Navier-Stokes Code. Existing turbulence models are inadequate or
require empirical tuning to generate reasonable results. Current effort is
focused on the effect of turbulence on flow near the leading edge of turbine
blades. Figure 2 shows computed effect of upstream vortices on surface
temperature near the leading edge of a turbine blade.
248
HS(a). IMPROVED MODELING, PREBURNER FLOW
In this task, the objective is to obtain steady state reacting hydrogen data
of mean and fluctuating velocities and concentrations and to compare benchmark
data with predictions from computer models and evaluate turbulence-chemistry
interactions.
Computations of the 3D flow in the advanced turbopump turbines requires
knowledge of the condition of the gases exiting the burner. Current models
for predicting those conditions are inadequate. Fluctuating concentration and
velocity data can now be obtained with laser diagnostics. These measurements
are necessary to determine the unmixedness of the reacting flow and the
reaction rates. The measurements are also necessary for differentiating
between the various computer models.
For this task, a team of computer modelers and experimentalist have defined
the measurements required to verify turbulent-reacting flow models. Existing
optical techniques will be used to make measurements within the shear layer-
two component LDV, fluorescence for OH and temperature, and TiC14 for seeding
and H20 concentration.
The facility is now operational. Figure 3 is a photo of the rig, showing the
laser beams being used to make measurements.
HS(f). HIGH REYNOLDS NUMBER AND UNSTEADY HEAT TRANSFER EXPERIMENT
In this task, the objective is to develop a fundamental understanding of the
effects of high Reynolds number and Reynolds number variations, and also
upstream unsteadiness, on heat transfer in turbulent boundary layers typical
of turbine airfoils in the SSME turbopump turbines.
In order to be able to predict the surface pressure and temperature
distributions within engine flow passages, and accurate turbulence and
unsteadiness model is needed. Data in the proper range of Reynolds number and
disturbance frequency are necessary for accurate modeling. A new in-house
experimental rig, shown schematically in figure 4 has been built in which the
major features of an SSME turbine airfoil are simulated, particularly the
Reynolds number. A particular feature of the rig is the ability to span the
Reynolds number range from conventional gas turbine levels up to SSME levels.
Figure 5 shows a comparison of preliminary measurements and computations of
surface pressure and heat transfer coefficients. The facility is currently
being modified, and tests will be continuing.
2.<Ig
HS(g). UNSTEADY HEAT TRANSFER ANALYSIS
In this task, the objective is to formulate analytic models to aid in the
prediction of the unsteady aero-thermal loads expected in the SSME turbopump
turbines.
The ability to predict the aero-thermal loads in the turbine unsteady flow
environment is an essential input to the ability to predict life and
durability. There are two aspects to the unsteadiness which occurs on turbine
blades. The first is due to free stream turbulence and wakes shed from
upstream vanes and blades. The second is due to laminar/turbulent boundary
layer transition which occurs some distance downstream from the blade leading
edge. The transition effect on concave surface is being addressed in this
research program.
For the boundary layer transition experiments, and experimental approach is
being used to study the effects of concave curvature, which occurs on the
pressure side of the SSME turbine airfoils, on the transition process.
LSVT23 IMPROVED AERO AND HEAT TRANSFER PREDICTION
In this task, the objective is to improve the calculation of the aerodynamic
environment in low aspect ration turbines and experimentally obtain the
unsteady surface heat transfer response to a temperature disturbance.
Knowledge of the local flow environment of turbine vanes and blades is
essential for the accurate prediction of turbine temperature and heat transfer
rates. In addition, the response of the turbine blade surfaces to rapid
changes in stagnation temperature is unknown. Improved steady and unsteady
heat transfer prediction is required for improved life and for turbine
efficiency. An existing quasi-3D computer code will be activated at Calspan
and used to compute pressure distributions over stator/rotor surfaces,
substantially reducing the uncertaintity in the aerodynamic environment and
providing a reliable base for heat transfer predictions. The experimental
phase will use actual SSME fuel turbine hardware, instrumented for time
resolved heat transfer and pressure measurements.
A detailed description of the latest results under this task will be presented
in another paper at this meeting.
25O
SUMMARY
Significant progress is being made in the Aerothermodynamic Loads Definition
Study, particularly in the turbomachinery area, where there is a distinct
overlap between the ETO efforts and research in the aeronautical _as turbine
field. The continuing work under this program will provide the knowledge,
understanding and design methodology that will allow the development of
advanced earth-to-orbit propulsion systems with high performance, extended
service life, automated operations, and diagnostics for in-flight health
monitoring.
251
Experimental and Computed Endwall Heat Transfer
Contours of Stanton Number xlO 3
Experiment (data of Boyle and Russell) 3D Calculation (RVC3D)
Cylindrical Leading Edge Temperature Distribution
Computed Effect of Free Stream Vortices
252
Reacting Shear Layer Facility
C-90-10693
CD-91-52228
ORIGYNAIL PA_E
BLACK AND WHITE PHOTOGRAPH
253
High Reynolds Number Heat Transfer Rig
Reynolds Nuniber up Io 7,500,000
Test section cutaway
_-_ _ Test section
Turbulence _.__ "_ /"
- ,_._ \ . _-Boundary layer control (typ, 1 of 4)generating _rdl-'% \ ..../
grid _ ,_:2_;_ _ \ / //-- Transition sectionI "/F_i<_ _ //,, _Flowcond.ionlng
_ '- I supply
_- / I exhaustdeT°ltitude _ _._-I_L_J\or.ice 
air filter
CD-91-52229
High Reynolds Number Heat Transfer
Comparison of Measured and Computed Blade Surface Relative
Pressure and Heat Transfer Coefficient
Static to 1.0 __z_z_j_
total
pressure
ratio
.9 t l I I I I I I I I
LE TE
400 _ SS PS
Heat
transfer
coefficient,
W/m 2 oK
0 l l I I I l I I I I
LE
Computational
tools appear to
accurately
capture high
Reynolds
number effects
CD-91-52230
254


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