Patent Publication Number: US-2013239579-A1

Title: Method of controlling engine performance

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is a continuation of U.S. patent application Ser. No. 12/590373 filed Nov. 6, 2009, which is incorporated herein by reference. 
    
    
     FIELD OF THE INVENTION 
     The invention relates to managing engine and turbine performance. In particular, the invention relates to using optical wavelength-dependent measurements to monitor and adjust parameters in engine and turbine combustion events. 
     BACKGROUND 
     Poor engine performance affects engine durability, power, thermal efficiency and pollution. Recently, efforts have been directed to optimizing power and propulsion systems for cleaner and lower environmental impact power generation. One approach included an integrated engine combustion monitoring system that uses a light communication channel (LCC) and a sensor, which are embedded in a cylinder head gasket, for monitoring air and fuel mixture, and/or products of combustion, pressure, or temperature. Although this approach offers real-time in-situ data acquisition of some engine performance parameters, the approach requires manually refining operational variables to the engine after sufficient data is acquired. Another attempt included an optoelectronic measuring device for monitoring combustion processes in the combustion chamber of an internal combustion engine during operation using optical sensors. The sensors were aligned so that the individual viewing angles of the sensors uniformly cover at least one predefined measuring sector of the combustion chamber. Unfortunately, this device required a large optical system that uses reflection/deflection to communicate a limited number of performance parameters that are useful only for testing engine performance in a controlled lab setting. 
     Recently introduced performance chips are used to boost engine power. An engine control unit (ECU) uses a formula and a large number of lookup tables to determine the fuel flow for a given operating condition. A chip in the ECU holds all of the lookup tables. The tables in the performance chip contain values that result in higher fuel/air ratios during certain driving conditions. For instance, they may supply more fuel at full throttle at every engine speed, or change the spark timing, or both. Performance chips as recently configured are not used for monitoring vital aspects of engine performance such as engine durability, output power versus efficiency, thermal efficiency, acoustic output, or exhaust constituents, to name a few. 
     What is needed is a method of real-time, in-situ monitoring pre-combustion state, during the combustion event and post-combustion event in a cylinder and adjusting the combustion event or at least a next combustion event by changing physical parameters and/or constituent parameters to control the engine or turbine performance. 
     SUMMARY OF THE INVENTION 
     The present invention provides a method of controlling engine performance that includes obtaining at least one optical wavelength-dependent measurement from at least one combustion event in at least one combustion chamber. The method further includes analyzing the optical wavelength-dependent measurement for determining adjustments to the at least one combustion event. Additionally, the method includes adjusting the at least one combustion event or at least a next combustion event by changing at least one physical parameter, or at least one constituent parameter, or at least one physical parameter and at least one constituent parameter to control the engine performance, where the physical parameter includes adjusting a turbine blade angle using a vane-adjust actuator in response to a signal from a controller. 
     According to one aspect of the invention, the combustion event can include a periodic event or a steady event. 
     In another aspect of the invention, the at least optical wavelength-dependent measurements are obtained using at least one optical sensor in the at least one combustion chamber and proximal to a region of the combustion event. 
     In a further aspect of the invention, the engine includes steady-flow engines or periodic-flow engines. Here, the steady-flow engines can be gas turbine engines, jet engines, or shaft power turbines. Further, the periodic-flow engines can be compression ignition engines spark ignition engines, laser ignition engines, pulse-jet engines, ram jet engines, or scram jet engines. According to this aspect, controlling the periodic-flow engine performance includes changing the combustion event physical parameters that include combustion chamber volume, instantaneous temperature level in a region proximal to a predetermined point, spatially averaged temperature level, temporal temperature level, averaged values of temperature level, temperature distribution within the combustion space, pressure, intake flow rate, exhaust flow rate, ignition timing, ignition energy per event, ignition energy delivery location and combustion duration. Also, according to the current aspect, controlling the steady-flow engine performance includes changing at least one the combustion process physical parameters that includes instantaneous temperature level, spatially distributed temperature level, temperature distribution within the combustion space, fuel flow rate, fuel composition, fuel temperature, ignition characteristics and combustion duration, wherein said ignition characteristics comprise timing, ignition energy, ignition energy delivery location or combustion duration. In this aspect, the periodic flow engine performance combustion event constituent parameters are measured during an event phase such as pre-combustion phase, combustion phase or end-stage combustion phase. Further, the periodic flow engine control is achieved using at least one actuator altering at least one combustion parameter such as composition of the total intake charge, pre-combustion fuel vapor or spray concentration and distribution, pre-combustion water vapor concentration, combustion chamber volume, ignition parameters (timing of initiation, duration of energy delivery, temporal profile of energy delivery, timing of the end of energy delivery), inlet charge temperature, intake valve operating parameters (opening event, duration, valve lift or equivalent, and closing event), exhaust valve operating parameters (opening event, duration, valve lift or equivalent, and closing event), fuel composition and fuel temperature. Here, portions of the total intake charge can include air, exhaust products, water droplets, water vapor or fuel additives. According to the current aspect, controlling the steady-flow engine performance includes least one actuator altering at least one combustion parameter such as air flow rate, various cooling air flow rates, secondary air flow rate, air temperature, air pressure, turbine tip clearance, fuel concentration distribution in space and time, water vapor concentration distribution in space and time, ignition timing, ignition energy delivery rate, energy delivery duration, fuel composition or fuel temperature. 
     According to another aspect, the engine performance can include engine durability, output power, thermal efficiency, acoustic output, or exhaust constituents, where the hierarchy of engine performance can be selected by an engine user. 
     In another aspect of the invention, the controller adjusts at least one the combustion parameter during the combustion events upon receiving the at least optical wavelength-dependent measurements. 
     According to another aspect of the invention, when the engine is a steady flow engine, engine durability is enhanced by adjusting a fraction of inlet air flow used for primary zone combustion, secondary air combustion and liner cooling in the response to commands from an engine control unit. 
     In another aspect of the invention, the engine performance is enhanced by altering fuel composition in response to commands from an engine control unit by injection of additives that can include of a knock suppressor in a spark ignition engine, a NOx suppressor, or a soot suppressor engine upon detection of an incipient condition, wherein the soot suppressor is used in a diesel or a gas turbine. 
     In another aspect of the invention, the engine is a steady flow engine having a steady-flow event, where at least one actuator alters at least one of the combustion parameters such as fuel concentration, oxygen concentration, air flow, combustion chamber pressure, combustion chamber temperature, fuel temperature or fuel composition. 
     In a further aspect, the engine is a periodic engine having at least one periodic event, where at least one actuator alters at least one of the combustion parameters such as fuel concentration, oxygen concentration, combustion chamber pressure, combustion chamber temperature, ignition timing, ignition duration, intake valve timing, exhaust valve timing, intake valve duration, exhaust valve duration, fuel temperature or fuel composition. 
     In another aspect of the invention, a position indicating device is coupled to an engine control unit to facilitate compliance with all territorial or zonal requirements, where the position indicating device comprises a global positioning system. 
    
    
     
       BRIEF DESCRIPTION OF THE FIGURES 
       The objectives and advantages of the present invention will be understood by reading the following detailed description in conjunction with the drawing, in which: 
         FIG. 1  shows a schematic flow diagram of the method of controlling engine performance according to the present invention. 
         FIG. 2  shows a drawing of the expert system for monitoring and optimizing engine performance of a periodic-flow engine according to the current invention. 
         FIG. 3  shows a drawing of the expert system for monitoring and optimizing engine performance of a steady-flow engine according to the current invention. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Although the following detailed description contains many specifics for the purposes of illustration, anyone of ordinary skill in the art will readily appreciate that many variations and alterations to the following exemplary details are within the scope of the invention. Accordingly, the following preferred embodiment of the invention is set forth without any loss of generality to, and without imposing limitations upon, the claimed invention. 
     The current invention provides an expert system for monitoring and optimizing engine performance. Specifically, the invention provides a method of monitoring a combustion event in a combustion chamber of an engine and, in real-time, altering the physical parameters and/or altering the constituent parameters in the combustion events using a high-speed controller to control the actuators, which can include high-speed actuators. The term combustion event includes a periodic event in periodic flow engines or a steady event in steady-flow engines. Here, the periodic flow engines can be compression ignition engines spark ignition engines, laser ignition engines, pulse-jet engines, ram jet engines, or scram-jet engines, and the steady-flow engines can be gas turbine engines, jet engines, or shaft power turbines. 
     An actuator alters at least one of the combustion parameters such as fuel concentration, oxygen concentration, combustion chamber volume, combustion chamber pressure, combustion chamber temperature, ignition timing, ignition duration, intake valve timing, exhaust valve timing, intake valve duration, exhaust valve duration, or fuel temperature. The controller adjusts at least one combustion parameter during the combustion events, or at least one before the next event in periodic-flow engines upon receiving the commands from the ECTU, based on all of the inputs including optical wavelength-dependent measurements. 
     Referring to the figures,  FIG. 1  shows a flow diagram of the method of controlling engine performance  100  according to the present invention. The flow diagram  100  shows an engine  101  where at least one optical wavelength-dependent measurement is obtained  102 , where the measurement can include any sophisticated optical measurement, for example line-of-sight absorption spectroscopy, wavelength modulation spectroscopy applied, planar laser-induced fluorescence (PLIF), wavelength-multiplexed, fiber-optic-based, line-of-sight, diode-laser absorption, multi-spectral detection, wavelength modulation spectroscopy using at least one tunable diode-laser sensor, the ratio of measured absorbances of two water vapor overtone transitions in the near infrared using a tunable diode laser, a scanned wavelength technique with wavelength modulation and 2 f detection using at least one diode laser, density inferred from spectroscopic absorption by an oxygen feature, velocity obtained from a Doppler frequency shift between absorption features from two crossed paths, two tunable diode laser temperature sensors comprising a first sensor using direct absorption and a second sensor using wavelength-modulation spectroscopy with second-harmonic detection, spectrally resolved laser-induced fluorescence (LIF), a diode laser absorption sensor inferring temperature from a ratio of optical absorption for two overtone transitions and H 2 O concentration determined from inferred temperature and absorption for one of the transitions, time-resolved absorption-based measurements of temperature and fuel vapor concentration using a two-wavelength mid-IR laser and a difference-frequency-generation laser. Further shown in  FIG. 1  the method includes analyzing the optical wavelength-dependent measurement  104  and, in combination with other inputs, determining adjustments to the combustion event  106 . Additionally, the method includes adjusting the combustion event  108  or at least a next combustion event by changing at least one physical parameter or, at least one constituent parameter, or at least one physical parameter and at least one constituent parameter to optimize the selected engine performance parameters according to the relative importance of engine durability, output power, thermal efficiency, acoustic output, or exhaust constituents. Here, the engine performance can be selected by an engine user, where the engine user is able to select which performance parameter is to be optimized depending upon the operator&#39;s needs at the time. For example, a pilot on take off or climb out would optimize for power. A VLCC engineer with 3,000 nautical miles remaining to reach port may optimize for fuel efficiency but opt to minimize emissions when nearing port. A freight vehicle may select for maximum emissions control when operating in a high-density urban environment, to name a few. 
       FIG. 2  shows a drawing of the expert system for monitoring and optimizing engine performance of a periodic-flow engine  200  according to the current invention. Shown in  FIG. 2  is an engine block  202  with a combustion chamber and a piston  206 . Further shown is an intake valve  208  and an exhaust valve  210 , a spark plug  212  for providing a spark to ignite a combustion event  214 , where it is understood that other engine types, such as diesel engines, do not require a spark plug  212  to initiate a combustion event  214 . The current embodiment shown in  FIG. 2  includes a combustion chamber volume displacement device  216  and an optical sensor  218 , where in this example the optical sensor  218  is proximal to a region of the combustion event  214  and may include a light source  220  such as a laser for facilitating optical measurement of wavelength-dependent information  222  from a combustion event  214 . In  FIG. 2  the sensor  218  measures combustion event constituent parameters in an event phase such as pre-combustion phase, combustion phase or end-stage combustion phase, and the measurement is received by a measurement analyzer  226  that may function in real-time. The analyzer sends the results to a controller  228  for determining what modifications, if any, need to be made to the combustion event  214 . If the controller  228  determines changes to the combustion event  214  are needed, a signal is provided to an actuator to change at least one physical parameter and/or at least one constituent parameter relating to the present or subsequent combustion event  214 . For example, the controller  228  can operate an intake actuator  230  to provide real-time adjustment of an intake parameter  232 , where  FIG. 2  shows the intake parameter  232  as a generic circle to represent any one of the intake parameters that can include, total intake charge per intake event (or flow rate for steady flow), pre-combustion fuel vapor or spray concentration and distribution, pre-combustion water vapor concentration, intake temperature, fuel temperature, intake valve operating parameters such as opening event, duration, valve lift or equivalent, and closing event. Here, the total intake charge can include air, exhaust products, water droplets or water vapor. 
       FIG. 2  further shows the controller  228  can operate an exhaust actuator  234  to provide real-time adjustment to an exhaust parameter  236 , where  FIG. 2  again shows a generic circle to represent any one of the exhaust parameters that can include exhaust valve operating parameters such as opening event, duration, valve lift or equivalent, and closing event, regeneration of the exhaust heat to improve the combustion event  214 , recirculation of exhaust constituents to the combustion event  214 , 
     According to the current embodiment, the controller  228  can operate a sparkplug actuator  238  to operate on the spark plug  212  (the spark plug represents any other ignition generator) and provide real-time adjustment to the ignition parameter that can include timing of initiation, duration of energy delivery, temporal profile of energy delivery, timing of the end of energy delivery. 
     The controller  228  can further operate a combustion chamber volume actuator  240  to operate on the combustion chamber volume displacement  216  and provide real-time adjustment to the volume of the combustion chamber  204  between compression events. 
     The controller  228  can operate any or all of the actuators to alter combustion parameters such as fuel concentration, oxygen concentration, combustion chamber volume, combustion chamber pressure, combustion chamber temperature, ignition timing, ignition duration, intake valve timing, exhaust valve timing, intake valve duration, exhaust valve duration, or fuel temperature. 
     In another aspect of the invention, fuel additives are used to modify the exhaust emissions, where a probe  242  is disposed in the exhaust stream with the sensor input fed to the controller  228  enabling corrective action to be taken in real time. In one aspect, an environmental control agency for a jurisdiction whose territory the vessel/aircraft/truck is entering, a down-loadable file is provided using a positioning indicating device  244 , such as a global positioning system (GPS), is captured and reviewed for compliance showing the data stream from the exhaust. The environmental control agency provides a time and location stamp and identifies any out of compliance events. Here, the down-loadable file has limited write/erase access to the file so that it couldn&#39;t be modified. 
       FIG. 2  shows the controlling of a periodic flow engine performance by changing the combustion event physical parameters such as inlet charge temperature by blending air at a controlled temperature with the intake charge using a fast-acting valved injector. Alternatively, the fuel to air ratio could be changed from combustion event to combustion event by changing the fuel injector parameter. 
     In a further aspect of the invention, the engine performance is enhanced by altering fuel composition in response to commands from an engine control unit by injection of additives such as injecting of a knock suppressor in a spark ignition engine or a soot suppressor in a diesel of gas turbine engine upon detection of an incipient condition. 
     According to the invention, the engine can include steady-flow engines or periodic flow engines, where the steady-flow engines can be gas turbine engines, jet engines, or shaft power turbines, and the periodic flow engines can be compression ignition engines spark ignition engines, laser ignition engines, pulse jet engines, ram jet engines, or scram jet engines. 
       FIG. 3  shows a drawing of the expert system for monitoring and optimizing engine performance of a steady-flow engine  300  according to the current invention. Shown in  FIG. 3  is a steady-flow engine housing  302  with a combustion chamber  304 , where the top chamber  304  is shown with some of the monitoring and control elements and the bottom chamber  304  is shown with other monitoring and control elements to simplify the drawing, and it is understood that one or more combustion chambers  304  can include all of the monitoring and control elements discussed here. Shown is an air intake region  306 , a compression region  308 , a combustion region  310  having the combustion chambers  304  and an exhaust region  312 . The current embodiment shown in the top combustion chamber  304  includes an optical sensor  316 , where in this example the optical sensor  316  is proximal to a region of the combustion process  318  and includes a light source  320 , such as a laser, for facilitating the measurement of the wavelength-dependent information  322  from the combustion process  318 . In  FIG. 3 , the optical sensors  316  measure combustion process constituent parameters in the pre-combustion region  315 , the primary combustion region  317  and the secondary combustion region  319  as shown in the lower combustion chamber  304 , where the measurements are received by a measurement analyzer  331  which may function in real-time. The analyzer sends the results to a controller  324  for determining what modifications if any, need to be made to the combustion event  318 . If the controller  324  determines changes to the combustion process  318  are needed, a signal, which may be real-time or suitably averaged is provided to an actuator to change at least one physical parameter and/or at least one constituent parameter relating to the combustion process  318 . For example, the controller  324  can operate a fuel intake actuator  326  to provide real-time adjustment of a fuel intake parameter  328 , where  FIG. 3  shows the fuel intake parameter  328  as a generic circle to represent any one of the fuel intake parameters that can include for example, instantaneous fuel flow rate, pre-combustion fuel vapor or spray concentration and distribution, pre-combustion water vapor concentration, or fuel temperature. 
     As shown, a sensor  330  is disposed in the exhaust stream  312  to provide exhaust data to the controller  324 , where the controller  324  adjusts at least one actuator altering at least one combustion parameter that can include primary air flow rate, secondary air flow rate, air temperature, fuel concentration distribution in space and time, water vapor concentration distribution in space and time, ignition timing, ignition energy delivery rate, energy delivery duration, fuel composition and fuel temperature.  FIG. 3  further shows the lower combustion chamber  304  having the combustion chamber lining  321  having operable valves  323  to open and close ports  323   b  in the secondary combustion region  319  of combustion chamber lining  321  to control the combustion event  318  cooling. The ports  323   b  may be smaller near the front of the flow and become progressively larger down stream, and are operated by the combustion chamber thermal actuator  325  as instructed by the controller  324 . The combustion chamber  304  further includes one or more thermal monitoring elements  327  for monitoring the temperatures of the combustion chamber lining  321 , the combustion event  318  and the air temperatures inside and outside of the combustion chamber lining  321 . Here a generic circle represents the monitoring elements for determining the total flow parameters in the combustion region  310 . The thermal monitoring elements can be a pyrometer, thermocouples or other such sensors. 
       FIG. 3  further shows the controller  324  disposed to operate a vane-adjust actuator  332  to adjust the angle of the turbine blades  334  in response to signals from the controller  324 . Turbine efficiency can be maintained at an optimum value if the angle of the turbine blades  334  with respect to the combustion flow parameter can be adjusted as the load point changes. 
     Another factor that affects efficiency in a steady-flow engine  300  is the clearance between the tips of the turbine blades  334  and the shroud  338  surrounding the turbine  334 . Leakage across the tips of the blades  334  represents a loss that must be minimized. According to the current invention, the clearance between the tips of the turbine blades  334  and the shroud  338  can be adjusted by a shroud actuator  340  that moves a moveable shroud  338  to change the clearance between the tips of the turbine blades  334  and the turbine shroud  338 . The invention further includes an inductive, capacitive or acoustic detector  342 , to determine when the blades  334  approach or touch the shroud  338 . According to another aspect of the invention the clearance between the tips of the turbine blades  334  and the turbine shroud  338  are altered by adjusting the temperature and/or the flow rate of the cooling airflow between the shroud  338  and the tips of the turbine blades  334 . Such temperature adjustment is done by the controller  324 , where the temperature of the shroud  338  is measured by a shroud temperature sensor  344 . 
     According to the current invention, controlling the steady-flow engine performance includes changing at least one of the combustion process physical parameters such as time-averaged cooling air temperature level and/or temperature distribution cooling air flow rate and ignitor performance (energy delivered or location) controlling the steady-flow engine performance requires at least one actuator altering at least one combustion parameter such as an air flow rate (primary, secondary or cooling), the fuel concentration distribution in space and time, water vapor concentration distribution in space and time, ignition timing, ignition energy delivery rate, energy delivery duration, fuel composition and fuel temperature. 
     According to the current aspect, controlling the steady-flow engine performance includes least one actuator altering at least one combustion parameter such as primary or secondary or cooling air flow rate, fuel concentration distribution in space and time, water vapor concentration distribution in space and time, ignition characteristics that include ignition energy delivery rate and energy delivery duration, fuel composition and fuel temperature. 
     According to another aspect of the invention, when the engine is a steady flow engine, engine durability is enhanced by adjusting a fraction of inlet air flow used for primary zone combustion, secondary air combustion and liner cooling in the response to commands from an engine control unit. 
     The present invention has now been described in accordance with several exemplary embodiments, which are intended to be illustrative in all aspects, rather than restrictive. Thus, the present invention is capable of many variations in detailed implementation, which may be derived from the description contained herein by a person of ordinary skill in the art. 
     All such variations are considered to be within the scope and spirit of the present invention as defined by the following claims and their legal equivalents.