Abstract:
A removable instrumentation assembly and probe for use in simultaneously measuring dynamic pressure, at least one static pressure, and temperature for a gas turbine combustor. The instrumentation assembly allows combustor performance analysis as well as monitoring of component integrity through dynamic pressure fluctuations. The instrumentation assembly includes a probe having a plurality of passages, each connected to tubular conduits for measuring and recording respective pressures. In the preferred embodiment, dynamic pressures from within a combustion chamber are measured and recorded along with static pressures within the combustion chamber and outside of the combustion chamber, along with external air temperature.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     This invention relates to gas turbine combustors and more specifically to a measurement device for quantifying combustor static and dynamic pressure levels as well as temperature. 
     2. Description of Related Art 
     It is a well known requirement to measure and monitor the pressure and temperature levels within a combustion system in order to ensure acceptable system durability and reliability. Within a combustion system, pressure fluctuations occur as part of the combustion process, and this is especially common with fuel-lean combustion systems. As combustion systems become more air-rich due to a lower fuel/air ratio, stability of the flame within the combustor becomes a concern. It is this instability that is a common driver of combustion dynamics. Excessive combustion dynamics can cause premature failure and require replacement of combustion hardware. Typically, a variety of equipment is required in order to measure the static pressures, dynamic pressures, as well as temperature. Combustion systems of the prior art have been known to use internally mounted dynamic pressure transducers, externally mounted accelerometers, or optical sensors to detect combustion dynamic pressure levels. With externally mounted accelerometers, only dynamic pressure was recorded. Optical sensors correlated spectral acoustic frequency of the ultraviolet flame emission with dynamic pressure waves characteristic of combustion dynamics. Meanwhile, static pressure levels were obtained by mounting separate pressure taps at the areas of interest while temperatures were measured through individual thermocouples. 
     While each of these devices may be acceptable individually to measure dynamic pressure, static pressure, or temperatures, multiple installations of costly instrumentation are required in order to capture all three types of data. What is needed is a device that can perform all of the above-described functions while requiring minimal installation time and at a reasonable cost. 
     SUMMARY AND OBJECTS OF THE INVENTION 
     The invention facilitates the acquisition of combustor diagnostic information such as dynamic pressure fluctuations, static pressure levels, combustion system pressure drop for mass flow correlation, and temperature with minimal equipment, installation time, or capital investment. In an exemplary embodiment a probe, which can easily be removed from a combustor, is connected to an instrumentation assembly that is capable of simultaneously measuring dynamic pressure, temperature, and at least one static pressure for a gas turbine combustor. The ease of installation allows rapid performance point benchmarking of different ambient day conditions. This information is critical to ensure low emissions operations over a range of ambient conditions. The removable probe is utilized in an instrumentation assembly that includes a plurality of conduits fixed to the probe as well as means for measuring and recording each of the pressures and temperatures. 
     It is an object of the present invention to provide a removable probe for use in a gas turbine combustor wherein the probe is capable of simultaneously measuring dynamic pressure, temperature, and at least one static pressure. 
     It is a further object of the present invention to provide a removable instrumentation assembly requiring minimal installation time and reduced cost. 
     In accordance with these and other objects, which will become apparent hereinafter, the instant invention will now be described with particular reference to the accompanying drawings. 
    
    
     BRIEF DESCRIPTION OF DRAWINGS 
     FIG. 1 is a perspective view of the instrumentation assembly and removable probe in accordance with the present invention. 
     FIG. 2 is an end view of the removable probe in accordance with the present invention. 
     FIG. 3 is a cross section view of the removable probe in accordance with the present invention. 
     FIG. 4 is an additional cross section view of the removable probe in accordance with the present invention. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Referring to FIG. 1, a removable instrumentation assembly  10  for use in a gas turbine combustor is shown. Instrumentation assembly  10 , which is capable of simultaneously measuring combustor dynamic pressure, temperature, and at least one static pressure, comprises a probe  11 , a plurality of tubular conduits, a plurality of cables, as well as measurement and recording devices. Referring to FIGS. 2-4, probe  11  includes a housing  12 , preferably generally circular in cross section, having a first end  13 , a second end  14 , a centerline A—A, an outer surface  15 , and a plurality of passages contained within housing  12 . Probe  11  is configured such that, when installed in a combustor, second end  14  is flush to a combustor chamber wall, as shown in FIGS. 3 and 4. Due to the operating environment, probe  11  is manufactured from a high temperature alloy such as nickel-based or cobalt-based alloy. A first passage  17  has a first diameter D 1  and extends from first end  13  to second end  14  and is coaxial to centerline A—A. Radially outward of first passage  17  is a second passage  18  that has a second diameter D 2  and extends from first end  13  to a first opening  19  in outer surface  15 . Located within second passage  18  is a first thermocouple  22  extending into first opening  19  for measuring the temperature of a fluid medium contained within first opening  19  and second passage  18 . Orientation of second passage  18  and first thermocouple  22  can be at any position desired about housing  12 . For most accurate temperature readings it is preferred that first thermocouple  22  be positioned directly in line with oncoming combustion gas flow, as shown in FIGS. 2 and 3. Also located in housing  12  is a third passage  20  having a third diameter D 3  with third passage  20  extending from first end  13  to a second opening  21  in outer surface  15 . First opening  19  is sized to provide sufficient exposure of thermocouple  22  to the surrounding combustion gases, and in the preferred embodiment, first opening  19  is larger in area than second opening  21 . As shown in FIG. 2, third passage  20  is also radially outward of first passage  17  but is preferably oriented at a circumferential angle relative to second passage  18 . For optimum static pressure measurement, second opening  21  is oriented such that it is generally perpendicular to the flow of combustion gases within a combustor, as shown in FIGS. 2 and 4. As probe  11  is configured in the preferred embodiment, first diameter D 1  of first passage  17  is greater than either second diameter D 2  or third diameter D 3 , of second passage  18  and third passage  20 , respectively. It is important to note that the number of passages dedicated to measuring static pressure is determined by the number of plenums that probe  11  passes through. That is, if probe  11  passes through one plenum surrounding a combustor liner and is measuring the static pressure within a combustor liner, there will be two passages dedicated for measuring static pressure, as is disclosed in the preferred embodiment of probe  11  and shown in FIG.  4 . Referring back to FIG. 3, along outer surface  15  of housing  12 , is a second thermocouple  16  that extends to proximate second end  14 . This second thermocouple can be added to probe  11  if it is desired to measure and record temperature of a fluid medium contained within a combustor chamber wall. Second thermocouple  16  may be fixed to outer surface  15  in a variety of configurations including radially outward of outer surface  15  or recessed within housing  12 . 
     Probe  11 , which is inserted into a combustion system, captures the fluid medium pressure and temperature, which is then transmitted, measured, and recorded by other components of the instrumentation assembly. Referring back to FIG.  1  and to FIG. 3, a first tubular conduit  23  is fixed to probe  11  at first end  13  such that it is in fluid communication with first passage  17 . First tubular conduit  23  extends from probe  11 , through an isolation valve, and to transducer mounting block  24 , which contains a dynamic pressure transducer  25  for measuring the dynamic pressure of the fluid medium within first passage  17  and first tubular conduit  23 . A first cable  26  is fixed to transducer mounting block  24  and extends from transducer mounting block  24  to a means for recording the dynamic pressure of the fluid medium within first conduit  23 , typically an electronic monitoring system programmed to record data at predetermined intervals. 
     A second tubular conduit  27  is fixed to transducer mounting block  24  and extends to a means for measuring the internal static pressure  28  of the fluid medium contained within second tubular conduit  27 , which was transmitted by first tubular conduit  23 . The fluid medium within second tubular conduit  27 , as with first tubular conduit  23 , is captured by probe  11  from within a combustion chamber. Fixed to and extending from means for measuring internal static pressure  28  is a second cable  29  that extends to a means for recording the internal static pressure within second tubular conduit  27 . 
     Referring now to FIGS. 1 and 4, a third tubular conduit  30  is fixed to probe  11  at first end  13  and is in fluid communication with third passage  20 . Third tubular conduit  30  extends from probe  11  through a shutoff valve  31  to a means for measuring external static pressure  32  of the fluid medium contained within third tubular conduit  30 . The fluid medium within third tubular conduit  30  is captured by the portion of probe  11  which is external to a combustion chamber wall, yet internal to a combustor casing wall, as shown in FIG.  4 . Fixed to and extending from means for measuring external static pressure  31  is a third cable  33  that extends to a means for recording the external static pressure within third tubular conduit  30 . 
     One skilled in the art will understand that the static pressure level measured at second opening  21  and third passage  20  can be obtained by alternate means. For example, static pressure levels at this location in the combustion system can be calculated from a total pressure reading if other factors such as mass flow and velocity of combustor gas flows are known. Total pressure can be determined using this same probe configuration if second opening  21  and third passage  20  are in line with the oncoming combustor gas flow. 
     While the invention has been described in what is known as presently the 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 within the scope of the following claims.