Patent Publication Number: US-9885609-B2

Title: Gas turbine engine optical system

Description:
This application claims priority to U.S. Patent Appln. No. 62/002,550 filed May 23, 2014. 
    
    
     BACKGROUND 
     The present application relates to an optical system and more particularly to an optical system for monitoring chambers within a gas turbine engine. 
     Gas turbine engines include a compressor section that compresses air and a fuel system that delivers a mixture of fuel and the compressed air to a combustor for ignition and thus the production of hot combustion gasses in an annular combustion chamber. During engine operation, anomalies may occur within or downstream of the combustor that may increase emissions of regulated combustion products and/or damage internal engine components such as the turbine section. Such anomalies may include flame-out within the combustor, improper flame temperature, fuel mal-distribution and changes to fuel composition and/or mixture ratios. Without proper detection and mitigation of these and other anomalies, the gas turbine engine may not meet emission standards and may require avoidable maintenance. 
     SUMMARY 
     A turbine engine optical system according to one, non-limiting, embodiment of the present disclosure includes a plurality of viewing ports in and circumferentially spaced about an engine case located downstream of a combustor section for depicting the spatial temperature distribution in an annular exhaust chamber defined between the engine case and an exhaust cone; and at least one optical device constructed and arranged to receive depictions through the plurality of viewing ports to detect at least exhaust temperature distributions. 
     Additionally to the foregoing embodiment, the device includes a controller for receiving a depiction input signal from the at least one optical device, analyzing the input signal, and outputting a control signal to control a parameter affecting combustion in a combustion chamber of the combustor section. 
     In the alternative or additionally thereto, in the foregoing embodiment, the control signal controls a fuel pump of a fuel system. 
     In the alternative or additionally thereto, in the foregoing embodiment, the control signal controls a fuel flow control valve of a fuel system. 
     In the alternative or additionally thereto, in the foregoing embodiment, the control signal controls combustor air flow in a fuel-air mixer. 
     In the alternative or additionally thereto, in the foregoing embodiment, the device includes a controller for receiving a depiction input signal from the at least one optical device, analyzing the input signal, and storing the data for future reference. 
     In the alternative or additionally thereto, in the foregoing embodiment, the at least one optical device is a laser absorption spectroscopy device. 
     In the alternative or additionally thereto, in the foregoing embodiment, the at least one optical device is a sensor array including a plurality of pixels operable to capture the images. 
     In the alternative or additionally thereto, in the foregoing embodiment, the device includes at least one multispectral mask array located between the respective at least one optical device and the plurality of viewing ports, and an attenuation mask orientated in front of the multispectral mask array for obtaining proper exposure of each of the plurality of pixels. 
     In the alternative or additionally thereto, in the foregoing embodiment, the multispectral mask array has a plurality of cells with each cell associated with a respective pixel, and each cell is one of a plurality of band-pass filter types with the plurality of band-pass filter types being distributed across the multispectral mask array. 
     In the alternative or additionally thereto, in the foregoing embodiment, the controller utilizes a depiction reconstruction algorithm to reconstruct a depiction. 
     In the alternative or additionally thereto, in the foregoing embodiment, each one of the plurality of viewing ports has a dedicated optical device of the at least one optical device. 
     In the alternative or additionally thereto, in the foregoing embodiment, the at least one optical device is an infrared laser. 
     A turbine engine according to another, non-limiting, embodiment includes an engine case concentrically orientated to an engine axis; and an optical system including a plurality of viewing ports in the engine case and circumferentially spaced from one-another for depicting a chamber defined in-part by the engine case, at least one optical device optically coupled to each of the plurality of viewing ports, and a controller for reconstructing the depiction of the at least one optical device into a substantially complete reconstructed depiction of the chamber. 
     Additionally to the foregoing embodiment, the chamber is annular in shape. 
     In the alternative or additionally thereto, in the foregoing embodiment, the chamber is an exhaust chamber. 
     In the alternative or additionally thereto, in the foregoing embodiment, the optical system is a laser absorption spectroscopy system. 
     In the alternative or additionally thereto, in the foregoing embodiment, the optical system is a laser diffraction system. 
     In the alternative or additionally thereto, in the foregoing embodiment, the optical system is a sensor array imaging system. 
     A method of monitoring a combustor of a gas turbine engine according to another, non-limiting, embodiment includes the steps of taking depiction of an exhaust chamber located downstream of the combustor; reconstructing the depiction in a controller; and correlating the reconstructed depiction to pre-established events of the combustor. 
     The foregoing features and elements may be combined in various combination without exclusivity, unless expressly indicated otherwise. These features and elements as well as the operation thereof will become more apparent in light of the following description and the accompanying drawings. It should be understood, however, the following description and figures are intended to be exemplary in nature and non-limiting. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Various features will become apparent to those skilled in the art from the following detailed description of the disclosed non-limiting embodiments. The drawings that accompany the detailed description can be briefly described as follows: 
         FIG. 1  is a schematic cross section of a gas turbine engine; 
         FIG. 2  is a schematic of the gas turbine engine detailing an optical system of the present disclosure; 
         FIG. 3  is a cross section of an exhaust chamber of the engine taken along line  3 - 3  of  FIG. 1 ; 
         FIG. 4  is a schematic of the optical system; 
         FIG. 5  is a perspective, exploded, view of a sensor and mask array of the optical system; and 
         FIG. 6  is a flow chart of a method of monitoring and/or controlling a combustor section. 
     
    
    
     DETAILED DESCRIPTION 
       FIG. 1  schematically illustrates a gas turbine engine  20  disclosed as a two-spool turbo fan that generally incorporates a fan section  22 , a compressor section  24 , a combustor section  26  and a turbine section  28 . The fan section  22  drives air along a bypass flowpath while the compressor section  24  drives air along a core flowpath for compression and communication into the combustor section  26  then expansion through the turbine section  28 . Although depicted as a turbofan in the disclosed non-limiting embodiment, it should be understood that the concepts described herein are not limited to use with turbofans as the teachings may be applied to other types of turbine engine architecture such as turbojets, turboshafts, three-spool turbofans, land-based turbine engines, and others. 
     The engine  20  generally includes a low spool  30  and a high spool  32  mounted for rotation about an engine axis A via several bearing structures  38  and relative to a static engine case  36 . The low spool  30  generally includes an inner shaft  40  that interconnects a fan  42  of the fan section  22 , a low pressure compressor  44  (“LPC”) of the compressor section  24  and a low pressure turbine  46  (“LPT”) of the turbine section  28 . The inner shaft  40  drives the fan  42  directly, or, through a geared architecture  48  to drive the fan  42  at a lower speed than the low spool  30 . An exemplary reduction transmission may be an epicyclic transmission, namely a planetary or star gear system. 
     The high spool  32  includes an outer shaft  50  that interconnects a high pressure compressor  52  (“HPC”) of the compressor section  24  and a high pressure turbine  54  (“HPT”) of the turbine section  28 . A combustor  56  of the combustor section  26  is arranged between the HPC  52  and the HPT  54 . The inner shaft  40  and the outer shaft  50  are concentric and rotate about the engine axis A. Core airflow is compressed by the LPC  44  then the HPC  52 , mixed with the fuel and burned in the combustor  56 , then expanded over the HPT  54  and the LPT  46 . The LPT  46  and HPT  54  rotationally drive the respective low spool  30  and high spool  32  in response to the expansion. 
     In one non-limiting example, the gas turbine engine  20  is a high-bypass geared aircraft engine. In a further example, the gas turbine engine  20  bypass ratio is greater than about six (6:1). The geared architecture  48  can include an epicyclic gear train, such as a planetary gear system or other gear system. The example epicyclic gear train has a gear reduction ratio of greater than about 2.3:1, and in another example is greater than about 2.5:1. The geared turbofan enables operation of the low spool  30  at higher speeds that can increase the operational efficiency of the LPC  44  and LPT  46  and render increased pressure in a fewer number of stages. 
     A pressure ratio associated with the LPT  46  is pressure measured prior to the inlet of the LPT  46  as related to the pressure at the outlet of the LPT  46  prior to an exhaust nozzle of the gas turbine engine  20 . In one non-limiting example, the bypass ratio of the gas turbine engine  20  is greater than about ten (10:1); the fan diameter is significantly larger than the LPC  44 ; and the LPT  46  has a pressure ratio that is greater than about five (5:1). It should be understood; however, that the above parameters are only exemplary of one example of a geared architecture engine and that the present disclosure is applicable to other gas turbine engines including direct drive turbofans. 
     In one non-limiting example, a significant amount of thrust is provided by the bypass flow path B due to the high bypass ratio. The fan section  22  of the gas turbine engine  20  is designed for a particular flight condition—typically cruise at about 0.8 Mach and about 35,000 feet (10,668 meters). This flight condition, with the gas turbine engine  20  at its best fuel consumption, is also known as Thrust Specific Fuel consumption (TSFC). TSFC is an industry standard parameter of fuel consumption per unit of thrust. 
     Fan Pressure Ratio is the pressure ratio across a blade of the fan section  22  without the use of a fan exit guide vane system. The low Fan Pressure Ratio according to one, non-limiting, example of the gas turbine engine  20  is less than 1.45:1. Low Corrected Fan Tip Speed is the actual fan tip speed divided by an industry standard temperature correction of (T/518.7 0.5 ), where “T” represents the ambient temperature in degrees Rankine. The Low Corrected Fan Tip Speed according to one non-limiting example of the gas turbine engine  20  is less than about 1150 fps (351 m/s). 
     Referring to  FIG. 2 , a schematic of the gas turbine engine  20  is illustrated wherein ambient air  58  enters the fan section  22  with an air portion  60  entering the compressor section  24 . The pressurized air portion enters a fuel system  62  of the combustor section  26  where at least a portion of pressured air portion mixes with fuel  64  and is injected into a combustion chamber defined by the combustor  56 . The combustor  56  ignites and combusts the fuel-and-air mixture, and then passes hot pressurized exhaust gas  66  into the turbine section  28 . The exhaust gas  66  passes through the turbine blades and vanes, turning the shafts  40 ,  50 . The gas  66  then exits the turbine section  28  and enters an annular exhaust path or chamber  68  generally defined by a downstream portion of an engine case  70  and an inner exhaust cone  72 . 
     The fuel system  62  may include a fuel-air mixer and/or fuel nozzle  74  that meters and controls the mixture of fuel and air, a servo controlled flow control valve  76  that controls the amount of fuel delivered to the fuel nozzle  74  and/or a fuel pump  78  that provides pressurized fuel  64  to the fuel nozzle  74 . The fuel system  62  may be any variety of fuel systems generally known in the art and may include (as examples) fuel nozzles having dedicated, variable speed, pumps; fuel systems having fuel nozzles each having a dedicated flow control valve with or without bypass valves and receiving fuel from a common fuel manifold (not shown) that is pressurized by at least one fuel pump. 
     Referring to  FIGS. 2 and 3 , an optical system  80  of the turbine engine  20  may include a plurality of viewing ports  82  (three shown), at least one optical device  84 , and a controller  90 . The viewing ports  82  may be located in and circumferentially spaced about the engine case  70  to view the exhaust gas  66  downstream of the combustor  56 . Each viewing port may be of a glass-type, constructed of a heat resistant transparent material such as fused quartz, synthetic sapphire, or others. Although not illustrated, each port  82  may also include a positioning mechanism and/or prism to alter the field of view within the chamber  68 . Each viewing port  82  may be optically coupled to a single optical device  84  with multiplexing capability. Alternatively, and as illustrated, each viewing port may be optically coupled to a dedicated optical device  84 , or any combinations of the above. The optical device  84  may be a thermal depiction optical device and may include an infrared laser capable of measuring infrared frequencies and intensities for the reconstruction of a spatial temperature distribution by the controller  90 . The optical device  84  may further be (or an addition thereto) a laser absorption spectroscopy device (e.g. diode lasers) capable of measuring/identifying specific elements or species in a gas. Yet further, the optical device  84  may be a laser diffraction device capable of measuring at least particle sizes in a gas stream. 
     Alternatively, the optical device  84  may be an imaging device or camera capable of measuring light generally emitted in at least the infrared region. If a camera, and referring to  FIG. 5 , the camera or sensor array  84  of the optical system  80  may further include a randomly distributed multispectral mask array  86  and a single attenuation mask  88  that may be associated with each sensor array  84 . The sensor array  84  may be a digital sensor array such as a CCD/CMOS sensor, or other spectral imaging device as is generally known in the art. 
     The sensor array  84  may be a focal plane array having a matrix or plurality of imaging, electronic, pixels  102 . The multispectral mask array  86  is generally position in front of the sensor array  84  and has a plurality of cells  104  with each cell aligned to a corresponding pixel  102 . The mask array  86  may further have a plurality of band-pass filter types  106 ,  108 ,  110  (three illustrated) that may be pseudo-randomly distributed amongst the cells  104  (i.e. each cell  104  has one of the three filter types  106 ,  108 ,  110 ). This pseudo-random order provides improved reconstructed images or depictions  98 ,  100  when used in conjunction with the algorithm  96  of the controller  90 . 
     Each filter type  106 ,  108 ,  110  is constructed to pass light emissions having wavelengths that fall within at least one specified wavelength range. Because the signal strength corresponding to one band-pass filter type may appreciably exceed the strength of another, the attenuation filter  88  may be needed to prevent overexposure (or over saturation) at cells  104  passing high signal strengths, and where exposure time is held constant across the sensor array  84 . The filter types may also be needed to block out background radiation from surrounding structure. 
     Referring to  FIGS. 2 and 4 , the optical system  80  may be constructed to monitor and depict a spatial temperature and/or constituent distribution within a chamber such as the exhaust chamber  68 , as one example. Each one of the optical devices  84  operate to take a depiction  92  of a portion of the chamber  68  within the specific optical device&#39;s field of view. Each device  84  may then send the depiction  92  as an input signal  94  to the controller or processor  90  that may apply a reconstruction algorithm  96  to reconstruct annular heat or species depiction  98  from the combined depictions  92  generated by each sensor array  84 . That is, the heat or species depiction  98  may be a two-dimensional, spatial discriminating, distribution of temperatures or species of interest within the chamber  68 . The controller  90  may further reconstruct a constituent depiction  100  that spatially identifies key gaseous components such as carbon dioxide (CO 2 ) and water (H 2 O), amongst others. The controller  90  may further process an output signal  101  (as dictated by the reconstructed depiction or data  98 ,  100 ) sent to other engine control systems and/or components to adjust engine operating parameters as determined by the depictions  92  in the exhaust chamber  68 . For example, the reconstructed depictions may be correlated to combustor performance and/or correlated to identify hot streaks in the combustor  56 , and one or both of the reconstructed depictions  98 ,  100  may be generally utilized to take corrective action and control aspects of the fuel system  62  such as the fuel nozzle  74  to adjust air flow, the flow control valve  76  to adjust fuel flow and/or the fuel pump  78 . 
     Alternatively or in combination, the re-constructed depictions  98 ,  100 , or data generally therefrom, may be stored electronically, and used during engine maintenance procedures. For instance, the turbine section  28  operating condition can be monitored. That is and as one example, deterioration of turbine clearances can be monitored knowing that such deterioration may cause the engine  20  to run hotter, yet have areas that are hotter or colder than an initial baseline such as a ring of hot or cold air on an outer diameter circumference. These conditions can be depicted directly or can be correlated to a temperature pattern or profile in the exhaust chamber  68  and thereby identified through the optical system  80 . 
     Referring to  FIG. 4 , the optical system  80  may communicate with the controller  90  through a wired channel, or alternatively, may be any other optical, wireless, radio channel, or any other type of channel capable of transmitting depictions between two points including links involving the World Wide Web (www) or the internet. 
     In yet another example, the viewing ports  82  may be in the engine case  70  generally at the combustor  56 , spatial distributions of fuel-to-air ratios and heat release in the reaction zone of the combustor can be monitored to control the performance of the combustor section  26  for fuel efficiency and reliability. 
     The optical system  80  as applied to the combustor  56  may also be applied to any portion of the engine  20  downstream of the combustor. For instance, the device may depict the exhaust chamber  68  and the reconstructed depictions  98 ,  100 , or data thereof, may be correlated to the performance of the combustor thus predicting combustor events that can be adjusted or corrected through output signals  101  of the controller  90 . 
     Referring to  FIG. 6 , a method of monitoring and/or controlling the combustor section  26  includes the first step  200  of taking depictions  92  of an exhaust chamber  68  through a plurality of viewing ports  82 . Then as step  202 , utilizing the controller  90  to reconstruct at least one depiction  98 ,  100  from the plurality of spatially discrete depictions  92 . The next step  204  correlates the reconstructed depiction(s) to pre-established events or anomalies of the combustor that may be learned through empirical trials or self-learning algorithms and/or on-board engine control software. As step  206 , the controller may generate an output signal  101  to control parameters of the fuel system  62  to alleviate the anomalies. 
     It is understood that relative positional terms such as “forward,” “aft,” “upper,” “lower,” “above,” “below,” and the like are with reference to the normal operational attitude and should not be considered otherwise limiting. It is also understood that like reference numerals identify corresponding or similar elements throughout the several drawings. It should be understood that although a particular component arrangement is disclosed in the illustrated embodiment, other arrangements will also benefit. Although particular step sequences may be shown, described, and claimed, it is understood that steps may be performed in any order, separated or combined unless otherwise indicated and will still benefit from the present disclosure. 
     The foregoing description is exemplary rather than defined by the limitations described. Various non-limiting embodiments are disclosed; however, one of ordinary skill in the art would recognize that various modifications and variations in light of the above teachings will fall within the scope of the appended claims. It is therefore understood that within the scope of the appended claims, the disclosure may be practiced other than as specifically described. For this reason, the appended claims should be studied to determine true scope and content.