U.S. patent application number 12/638186 was filed with the patent office on 2011-06-16 for methods of determining variable element settings for a turbine engine.
Invention is credited to Mohammad Waseem ADHAMI, Stephen Bartlett, Robert Coleman, Kenneth Meiners.
Application Number | 20110142602 12/638186 |
Document ID | / |
Family ID | 44143107 |
Filed Date | 2011-06-16 |
United States Patent
Application |
20110142602 |
Kind Code |
A1 |
ADHAMI; Mohammad Waseem ; et
al. |
June 16, 2011 |
METHODS OF DETERMINING VARIABLE ELEMENT SETTINGS FOR A TURBINE
ENGINE
Abstract
Variable elements of a turbine engine such as variable inlet
guide vanes, variable bleed valves and variable stator vanes can be
adjusted to provide a desired level of power and/or efficiency for
the turbine engine across a range of operating conditions. The
variable element settings typically determined through
experimentation when the engine is new. Unfortunately, over the
life cycle of the turbine engine, as wear occurs, the original
variable element settings may no longer provide a desired level of
power and efficiency. To correct this problem, offsets to the
original variable element settings are calculated based on
observable operational conditions which provide a measure of the
wear that has occurred. The offsets are applied to the original
variable element settings to generate corrected variable element
settings. These corrected variable element settings are then used
to configure the turbine engine. The corrected variable element
settings allow the turbine engine to continue to operate at a
desired level of power and/or efficiency over the life of the
turbine engine, despite any deterioration which may have occurred
due to normal life cycle wear.
Inventors: |
ADHAMI; Mohammad Waseem;
(Cincinnati, OH) ; Bartlett; Stephen; (Cincinnati,
OH) ; Coleman; Robert; (West Chester, OH) ;
Meiners; Kenneth; (Cincinnati, OH) |
Family ID: |
44143107 |
Appl. No.: |
12/638186 |
Filed: |
December 15, 2009 |
Current U.S.
Class: |
415/159 |
Current CPC
Class: |
F02C 9/20 20130101; F02C
9/18 20130101; F01D 17/162 20130101; F05D 2260/80 20130101 |
Class at
Publication: |
415/159 |
International
Class: |
F01D 17/16 20060101
F01D017/16 |
Claims
1. A method of determining at least one variable element setting
for a turbine engine, comprising: obtaining an original variable
element setting from a setting schedule based on a sensed
operational condition of the turbine engine; determining at least
one offset that is based on at least one sensed operational
condition of the turbine engine; and calculating a corrected
variable element setting based on the obtained original variable
element setting and the at least one offset.
2. The method of claim 1, wherein the at least one offset is based
on at least one sensed operational condition of the turbine engine
that provides a measure of the amount of wear experienced by the
turbine engine during its operational life.
3. The method of claim 1, wherein the obtaining step comprises
obtaining an original inlet guide vane setting, wherein the
determining step comprises determining an inlet guide vane offset,
and wherein the calculating step comprises calculating a corrected
inlet guide vane setting based on the original inlet guide vane
setting and the inlet guide vane offset.
4. The method of claim 3, wherein the obtaining step comprises
obtaining an original inlet guide vane setting that is based on a
sensed compressor exit pressure.
5. The method of claim 3, wherein the determining step comprises
determining the inlet guide vane offset based on a sensed exit
temperature of a turbine section of the turbine engine.
6. The method of claim 5, wherein the inlet guide vane offset is
also based on an exit temperature of a compressor section of the
turbine engine.
7. The method of claim 6, wherein the inlet guide vane offset is
also based on an exit pressure of a compressor section of the
turbine engine.
8. The method of claim 3, wherein the determining step comprises
determining the inlet guide vane offset based on an exit
temperature of a compressor section of the turbine engine.
9. The method of claim 3, wherein the determining step comprises
determining the inlet guide vane offset based on an exit pressure
of a compressor section of the turbine engine.
10. The method of claim 3, wherein the determining step comprises
determining the inlet guide vane offset based on an exit pressure
of a turbine section of the turbine engine.
11. The method of claim 3, wherein the determining step comprises
determining the inlet guide vane offset based on a rotational speed
of the turbine engine.
12. The method of claim 3, wherein the determining step comprises
determining the inlet guide vane offset based on a rotational speed
of the turbine engine that has been corrected for the ambient
temperature.
13. The method of claim 3, further comprising: obtaining an
original variable bleed valve setting that is based on a sensed
operational condition of the turbine engine; determining a variable
bleed valve offset based on at least one sensed operational
condition of the turbine engine; and calculating a corrected
variable bleed valve setting based on the original variable bleed
valve setting and the variable bleed valve offset.
14. The method of claim 13, wherein the at least one variable bleed
valve offset is based on the determined inlet guide vane
offset.
15. The method of claim 13, further comprising: obtaining an
original variable stator vane setting that is based on a sensed
operational condition of the turbine engine; determining a variable
stator vane offset that is based on at least one sensed operational
condition of the turbine engine; and calculating a corrected
variable stator vane setting based on the original stator vane
setting and the variable stator vane offset.
16. The method of claim 3, further comprising: obtaining an
original variable stator vane setting that is based on a sensed
operational condition of the turbine engine; determining a variable
stator vane offset that is based on at least one sensed operational
condition of the turbine engine; and calculating a corrected
variable stator vane setting based on the original stator vane
setting and the variable stator vane offset.
17. The method of claim 1, wherein the obtaining step comprises
obtaining an original variable bleed valve setting, wherein the
determining step comprises determining a variable bleed valve
offset, and wherein the calculating step comprises calculating a
corrected variable bleed valve setting based on the original
variable bleed valve setting and the variable bleed valve
offset.
18. The method of claim 17, further comprising: obtaining an
original variable stator vane setting that is based on a sensed
operational condition of the turbine engine; determining a variable
stator vane offset that is based on at least one sensed operational
condition of the turbine engine; and calculating a corrected
variable stator vane setting based on the original variable stator
vane setting and the variable stator vane offset.
19. The method of claim 1, wherein the obtaining step comprises
obtaining an original variable stator vane setting, wherein the
determining step comprises determining a variable stator vane
offset, and wherein the calculating step comprises calculating a
corrected variable stator vane setting based on the original
variable stator vane setting and the variable stator vane
offset.
20. A method of determining a variable element setting for a
turbine engine, comprising: obtaining an original variable element
setting from a schedule of settings that are experimentally
determined when the turbine engine is new, wherein the original
settings in the schedule are indexed to at least one operational
condition of the turbine engine; determining at least one variable
element setting correction factor that is based on at least one
sensed operational condition of the turbine engine, wherein the at
least one sensed operational condition provides an indication of
the amount of wear which the turbine engine has experienced during
its lifecycle; and calculating a corrected variable element setting
based on the obtained original variable element setting and the
determined at least one variable element correction factor.
Description
BACKGROUND OF THE INVENTION
[0001] Some turbine engines have variable geometry, or elements
which can be adjusted to ensure that the turbine engine provides
desirable power and/or efficiency over a range of operating
conditions and for a range of engine quality or deterioration
levels. For instance, a turbine engine could include an adjustable
inlet guide vane section. The inlet guide vanes can be adjusted to
control the flow of air entering the low pressure compressor.
[0002] A turbine engine could also include variable bleed
valves/doors, which are typically located at the exit of the low
pressure compressor. The bleed valves/doors could be controlled by
a single or multiple actuators. Further, the bleed valves could be
provided on both the low pressure compressor and the high pressure
compressor. The amount of air which is allowed to bleed off through
each of the individual bleed valves can be adjusted to ensure that
the engine provides a desirable level of power and/or efficiency
and compressor stability margins.
[0003] In addition, a high pressure compressor could include
variable stator vanes. The angle of the variable stator vanes can
be adjusted to ensure that the turbine engine provides a desirable
level of power and/or efficiency and compressor stability
margins.
[0004] A controller can be used to send signals to the variable
stator vane assembly in the high pressure compressor, to the
variable bleed valves/doors, and to the variable inlet guide vanes
to instruct these variable elements to assume a particular setting.
Thus, a controller can be used to adjust the settings of each of
these elements to ensure that the turbine engine provides a
desirable level of power and/or efficiency and compressor stability
margins for any given operational condition and turbine engine
quality.
[0005] The desirable settings for these variable elements of the
turbine engine are typically determined by experimentation when the
turbine engine is new. The result of the experimentation is a set
of "schedules," which list the settings to be used for each of the
variable elements based upon a sensed operational condition within
the turbine engine. For instance, the setting for the inlet guide
vanes could be determined using a schedule which lists settings for
various different high pressure compressor exit temperatures. The
variable bleed valve setting and the variable stator vane settings
could be based upon the rotational speed of the turbine engine. To
determine the desired settings for each of the variable elements of
the turbine engine, one would first sense the relevant operational
condition of the engine, and then consult the experimentally
determined schedules to find the proper setting. This setting would
then be applied to the variable element of the turbine engine
through the controller.
[0006] The schedules listing the settings for each of the variable
elements of the turbine engine are typically determined when the
engine is new. However, during the life of the turbine engine, wear
occurs. As a result of that wear, the settings provided in the
experimentally determined schedules may no longer provide a
desirable level of power and/or efficiency for the turbine
engine.
BRIEF DESCRIPTION OF THE INVENTION
[0007] In one aspect, the invention may be embodied in a method of
determining at least one variable element setting for a turbine
engine that includes the steps of obtaining an original variable
element setting based on a sensed operational condition of the
turbine engine from a setting schedule, determining at least one
setting correction factor that is based on a sensed operational
condition of the turbine engine, and calculating a corrected
variable element setting based on the obtained original variable
element setting and the at least one correction factor.
[0008] In another aspect, the invention may be embodied in a method
of determining a variable element setting for a turbine engine that
includes the steps of obtaining an original variable element
setting from a schedule of settings that are experimentally
determined when the turbine engine is new, wherein the original
settings in the schedule are indexed to at least one operational
condition of the turbine engine, determining at least one variable
element setting correction factor that is based on a sensed
operational condition of the turbine engine, wherein the sensed
operational condition provides an indication of the degree of wear
which the turbine engine has experienced during its lifecycle, and
calculating a corrected variable element setting based on the
obtained original variable element setting and the determined at
least one variable element correction factor.
BRIEF DESCRIPTION OF THE DRAWINGS
[0009] FIG. 1 is a diagram of the major elements of a turbine
engine that includes variable elements;
[0010] FIG. 2 is a diagram setting forth inlet guide vane settings
based on the high pressure compressor exit pressure;
[0011] FIG. 3 is a diagram setting forth variable bleed valve
settings based on a corrected high pressure compressor rotational
speed and the engine inlet temperature;
[0012] FIG. 4 is a diagram setting forth variable stator vane
settings based on the corrected high pressure compressor rotational
speed;
[0013] FIG. 5 illustrates how various observable operational
conditions of a turbine engine change over the lifetime of the
turbine engine;
[0014] FIG. 6 illustrates the values of a variable used to
calculate an offset, the value of the variable being determined
based upon a turbine exit temperature;
[0015] FIG. 7 illustrates the values of a variable used to
calculate an offset, the value of the variable being determined
based upon a compressor exit temperature;
[0016] FIG. 8 illustrates the values of a variable used to
calculate an offset, the value of the variable being determined
based upon a compressor exit pressure; and
[0017] FIG. 9 illustrates steps of a method of calculating a
corrected or adjusted inlet guide vane setting for a turbine
engine.
DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS
[0018] The basic elements of a turbine engine with variable
geometry are illustrated in FIG. 1. As shown therein, the turbine
includes a low pressure compressor 100, a high pressure compressor
200, a high pressure turbine 300 and a low pressure turbine
400.
[0019] The turbine engine illustrated in FIG. 1 includes an
adjustable inlet guide vane section 110. The inlet guide vanes 110
can be adjusted to control the flow of air entering the low
pressure compressor 100.
[0020] The turbine engine also includes variable bleed valves/doors
120, which are typically locates near the exit of the low pressure
compressor 100. The blood valves/doors 120 could be controlled by a
single or multiple actuators. In the illustrated embodiment, three
variable bleed valves/doors 120 are provided. However, only one or
any number of bleed valves could be provided. Further, the bleed
valves could be provided on both the low pressure compressor 100
and the high pressure compressor 200. The amount of air which is
allowed to bleed off through each of the individual bleed values
can be adjusted to ensure that the engine provides a desired level
of power and/or efficiency.
[0021] In addition, the high pressure compressor 200 includes
variable stator vanes 210. The angle of the variable stator vanes
can be adjusted to ensure that the turbine engine provides maximum
power and/or efficiency.
[0022] In the embodiment illustrated in FIG. 1, a controller 500
sends signals to the variable stator vane assembly 210 in the high
pressure compressor 200, to the variable bleed valves/doors 120,
and to the variable inlet guide vanes 110 to instruct these
variable elements to assume a particular setting. Thus, the
controller 500 can be used to adjust the settings of each of these
elements to ensure that the turbine engine provides maximum power
and/or efficiency for any given operational condition and turbine
engine quality.
[0023] The disclosed technology for controlling the variable
geometry elements of a turbine engine applies to singe spool or
multi-spool turbine engines. For purposes of describing the
technology, a two spool turbine engine will be used as an example.
It should be understood that the technology is equally applicable
to single spool turbines engines.
[0024] As noted above, the original settings for variable elements
of a turbine engine are typically determined through
experimentation on a new engine. The settings determine how to
configure the variable elements, given the current engine
operational conditions, to obtain a desired level of power and/or
efficiency. However, because of the wear which occurs over the
lifecycle of the turbine engine, the original settings for the
variable elements may not provide the desired level of power and/or
efficiency once the turbine engine has experienced appreciable
wear.
[0025] The methods and principles described below are intended to
allow an operator to adjust the original variable element settings
to account for the wear that has occurred. The basic idea is to
sense one or more operational conditions of the turbine engine to
obtain an indication of the degree of wear which has occurred.
Based upon the sensed operational conditions, one then calculates a
variable element offset which is applied to the original settings.
The offset is used to correct the original variable element
settings to create corrected or adjusted variable element settings.
And these corrected or adjusted variable element settings are then
used to configure the turbine engine for a desired level of power
and/or efficiency.
[0026] FIGS. 2, 3 and 4 provide three examples of variable element
setting schedules which could be established through
experimentation when a turbine engine is new.
[0027] FIG. 2 illustrates the settings for the inlet guide vanes of
a turbine engine. The settings are based upon the high pressure
compressor exit pressure, and the engine inlet temperature. Note,
there are different lines for the settings depending on the engine
inlet temperature. To determine a setting, one would first
determine the engine inlet temperature. One would then sense the
high pressure compressor exit pressure, and that value would then
be used to determine the inlet guide vane setting using the
appropriate temperature line. If the actual sensed temperature is
between two of the temperature lines, one could interpolate a value
by looking at the area between the two closest temperature lines.
As explained, this setting would provide a desired level of power
and/or efficiency when the engine is new.
[0028] FIG. 3 illustrates the settings for variable bleed valves of
a turbine engine. To determine the desired variable bleed valve
setting, one would first sense the engine inlet temperature. This
temperature would correspond to one of the four lines illustrated
in FIG. 3. One would also determine the corrected high pressure
compressor rotational speed. Using the corrected high pressure
compressor rotational speed, and the appropriate temperature line,
one then determines the variable bleed valve setting to provide a
desired power and/or efficiency for the turbine engine when the
turbine engine is new. If the actual sensed temperature is between
two of the temperature lines, one could interpolate a value by
looking at the area between the two closest temperature lines.
[0029] FIG. 4 is a diagram which indicates the variable stator vane
settings based upon the corrected high pressure compressor
rotational speed.
[0030] The schedules setting forth the settings for the variable
bleed valves and the variable stator vanes both rely, at least in
part, on the corrected high pressure compressor rotational speed.
The actual high pressure compressor rotational speed, which is also
called the "core speed," is corrected to account for the ambient
temperature at which the turbine engine is operating, or the high
pressure compressor inlet temperature. For instance, one formula
for determining the corrected high pressure compressor speed is
provided as follows:
Corrected Core Speed = Actual H P Compressor Speed H P Comp . inlet
Temp . 518.67 ##EQU00001##
[0031] The high pressure compressor inlet temperature in the
formula set forth above is to be entered in the formula in degrees
Rankin. The corrected core speed given by the formula is a
normalized speed which accounts for variations in the day-to-day
ambient temperature of the environment surrounding the turbine
engine.
[0032] FIG. 5 illustrates three key operational conditions of a
turbine engine that change over the lifecycle of the turbine
engine, as wear accumulates. As shown in FIG. 5, one would expect
the turbine exit temperature to gradually increase over the
lifecycle of the engine. Likewise, one would expect the high
pressure compressor exit temperature to gradually decline over the
lifecycle of the engine. One would also expect the high pressure
compressor exit pressure to gradually decline over the lifecycle of
the turbine engine. By sensing the actual values for one or more of
these parameters, one can determine the degree of wear which has
accumulated.
[0033] Of course, the three parameters illustrated in FIG. 5 are
not the only parameters that can provide an indication of wear.
Other values such as the turbine exit pressure, and the exit
temperature and exit pressure of the low pressure compressor, as
well as other parameters could also be used to determine or
approximate the degree of wear which has occurred. The important
point is that one senses the actual operational conditions of the
turbine engine to determine a state of deterioration of the turbine
engine.
[0034] Because different parameters can provide different
indications of the wear that has occurred, in some instances it may
be advantageous to use multiple observable parameters together to
calculate an offset that will be applied to the original variable
element settings. For instance, one could sense the actual turbine
exit temperature, the high pressure compressor exit temperature,
and the high pressure compressor exit pressure, and then use all
three of these sensed values together to calculate the offset.
[0035] One method of calculating an offset to be applied to the
original settings for the inlet guide vanes of a turbine engine
will now be described. However, it should be understood that the
following method is only one possible way of determining an offset
to be applied to the original variable inlet guide vane settings. A
variety of other methods can also be used to calculate such an
offset.
[0036] In this example method, one senses the turbine exit
temperature, and the temperature is used to determine the value of
a first variable. One also determines the high pressure compressor
exit temperature, and this temperature is used to determine the
value of a second variable. One also senses the high pressure
compressor exit pressure, and this pressure is used to determine
the value of a third variable. The first, second and third variable
values are then combined in some fashion to calculate an offset.
And this offset is then applied to the original variable inlet
guide vane settings.
[0037] FIG. 6 is a diagram illustrating how the turbine exit
temperature can be used to determine the value of a first variable
X. One would sense the actual exit temperature of the turbine, and
then consult the schedule illustrated in FIG. 6 to determine the
value of the variable X.
[0038] FIG. 7 illustrates a schedule used to determine the value of
a second variable Y, which is based upon the actual high pressure
compressor exit temperature. One would sense the actual high
pressure compressor exit temperature, and then consult the schedule
illustrated in FIG. 6B to determine the value of variable Y.
[0039] FIG. 8 is a schedule which is used to determine the value of
a third variable Z, which is based upon the high pressure
compressor exit pressure. One would measure the actual high
pressure compressor exit pressure, and then consult the schedule
illustrated in FIG. 8 to determine the value of variable Z.
[0040] One could then combine the three variables X, Y and Z to
determine an offset value. For instance, one could simply add the
three variables X+Y+Z to determine the value of an offset which is
then applied to the original settings for the inlet guide vanes. Of
course, the values of X, Y and Z could be mathematically combined
in some other fashion to determine the offset. For instance,
multipliers could be applied to one or more of the variable values
before they are added. Or, alternatively, two or more of the
variable values could be multiplied together. Any sort of
mathematical combination that is appropriate to obtain a useful and
accurate offset could be used.
[0041] In some instances, the amount of wear experienced by the
turbine engine could be approximated by checking the actual value
of an observable condition of the engine, such as the turbine
exhaust temperature or pressure. In other instances, the amount of
wear could be approximated by determining the amount or percentage
that the observable value has changed since the turbine was first
put in service. So, for instance, one could note the turbine
exhaust temperature when the engine is first put in service, then
check the turbine exhaust temperature later, after wear has
occurred, and calculate a percentage change in the value. And that
percentage of change could be used to obtain the value of a
variable that is ultimately used to calculate an offset.
[0042] Another factor that may play into determining the correct
value of a variable used to calculate an offset is the ambient
temperature and pressure. For instance, one might detect an
observable operating condition of a turbine engine, and then use a
chart or schedule to determine the value of a variable. And that
variable value might also be corrected for the current temperature
and/or atmospheric pressure. The corrected variable value would
then be used to calculate the offset.
[0043] The values provided in the schedules illustrated in FIGS.
6-8 could also be obtained through experimentation which is
conducted throughout the lifecycle of a typical turbine engine. In
this instance, the value of each of the individual variables would
have a basis in actual real world testing.
[0044] In addition, a fourth variable value could be used to
provide protection against a stall. For instance, a stall
protection variable A could be determined based upon the values of
one or more of the variables X, Y and Z. Alternatively, the value
of the stall protection variable A could be determined based on an
observable operational condition of the turbine. In other
instances, the value of the stall protection variable A could be
based on the number of hours that the turbine engine has been
operating since its last major servicing. The fourth variable value
A could then be mathematically combined with the first three
variable values X, Y and Z to determine the actual offset to be
used to correct the original inlet guide vane settings.
[0045] In addition, in each of the alternative methods described
above, all three of the variable values X, Y and Z are combined in
some fashion to determine the final offset value. In alternate
embodiments, only one or only two of the three variable values
could be combined to determine the actual offset. In addition, more
than three variable values could be used to determine the offset.
For instance, another variable value could be based upon another
observable operational condition of the turbine engine, and that
fourth variable value could be mathematically combined with one or
more of the first three variable values described above to
determine the actual offset value. The important point is that the
various different variable values are each based upon an observable
condition of the turbine engine which provides some indication of
the deterioration of the turbine engine. Those variable values are
then combined in some mathematical fashion to arrive at the offset
value.
[0046] FIG. 9 illustrates steps of a method of calculating a
corrected inlet guide vane setting. As illustrated in FIG. 9, the
method would start in step S700. The method would then proceed to
step S702 where the original inlet guide vane position would be
determined from the original schedule, based upon the high pressure
compressor exit pressure. The method would then proceed to step
S704 where the value of variable X would be determined based upon
the turbine exit temperature. The method would then proceed to step
S706 where the value of variable Y would be obtained based upon the
high pressure compressor exit temperature. The method would then
proceed to step S708 where the variable value Z would be determined
based upon the high pressure compressor exit pressure. Finally, in
step S710, a corrected inlet guide vane setting would be determined
based upon the values obtained in steps S702, S704, S706 and S708.
For instance, the values of the variable X, Y and Z would be
mathematically combined in some fashion to determine an offset
value. This offset value would then be applied to the original
inlet guide vane setting obtained in step S702 to calculate a
corrected or adjusted inlet guide vane setting.
[0047] In each of the methods described above, the actual sensed
operating conditions of a turbine engine are used to correct the
original inlet guide vane setting to account for deterioration of
the turbine engine. The same types of methods could be applied to
calculate a corrected variable bleed valve setting or a corrected
variable stator vane position. Here again, one would start with the
original setting from schedules illustrated in FIGS. 3 and 4, one
would determine an offset to be applied to that original setting
based on the state of deterioration of the turbine engine (as
reflected in one or more sensed operating conditions), and one
would then determine a corrected setting based upon the original
setting and the offset.
[0048] The actual variable values used to determine an offset could
change from one type of variable element of the turbine engine to
another. For instance, an offset for the variable bleed valve
setting could be based upon a first set of observable operational
conditions, whereas an offset for the variable stator vane setting
could be based upon a second set of observable operational
conditions. Moreover, during the lifecycle of a turbine engine,
different variable values might be used to create an offset for one
of the original settings. For instance, during the first half of
the normal lifecycle of a turbine engine, a first set of variable
values could be used to determine an offset to be applied to the
original inlet guide vane setting. However, during the second half
of the normal lifecycle of the turbine engine, a second different
set of variables could be used to calculate the offset for the
original inlet guide vane setting. Likewise, the mathematical
operations used to combine two or more variable values could also
change over the lifecycle of the turbine engine.
[0049] In the examples provided above, the inlet guide vane
settings, variable bleed valve settings and variable stator vane
settings are adjusted. However, to the extent the turbine engine
includes other elements which are also capable of variable
settings, those variable elements could also be adjusted based upon
the state of deterioration of the turbine engine as indicated by
observable operational conditions of the turbine engine.
[0050] While the invention has been described in connection with
what is presently considered to be the most practical and preferred
embodiment, it is to be understood that the invention is not to be
limited to the disclosed embodiment, but on the contrary, is
intended to cover various modifications and equivalent arrangements
included within the spirit and scope of the appended claims.
* * * * *