Rapid authentication method and system for aviation alternative fuel, medium and system thereof

Abstract

The invention relates to an aviation alternative fuel authentication scheme which comprises the following steps: a pre-screening step: a) fuel characteristic prediction based on a chemical component test; b) testing key physical and chemical properties of fuel; judging whether a formal fuel affirmation process can be entered or not; if not, correspondingly improving the refining process of the fuel; if yes, performing a fuel basic performance test, including 1-A) performing a physical and chemical performance test; 1-B) carrying out an applicable performance test; the fuel performance evaluation of the engine OEM company comprises the following steps: 2-A) carrying out core key index simulation evaluation; 2-B) carrying out model combustion chamber key index verification; judging whether additional authentication of the fuel is needed or not; if the additional authentication is needed, carrying out a part performance test; 4) carrying out a whole machine performance test; it is determined whether to issue a TSO certificate to the alternative fuel through security review.

Description

Technical Field

[0001] The present application relates to intersecting fields such as green energy, aircraft engines, and airworthiness technology, and specifically to a rapid certification method and certification system for aviation alternative fuels in aircraft engines. Background Art

[0002] At present, the aviation industry is highly dependent on oil. The global air transport industry consumes 1.5 to 1.7 billion barrels of jet fuel each year, all of which are extracted from oil. However, with the reduction of global oil reserves and the sharp fluctuations in oil prices, issues such as aviation energy security and economy have become more prominent. On the other hand, global climate change has also put forward requirements for the aviation industry to reduce carbon emissions. The International Air Transport Association (IATA) predicts that by 2030, carbon emissions from the aviation industry will increase at an annual rate of 5%. Currently, its carbon emissions account for 2.6% of the total carbon emissions (GHG) from human activities, and it is expected that by 2050, its carbon emissions will reach 3.0% of GHG. The emission reduction target proposed by the International Civil Aviation Organization (ICAO) is to reduce carbon emissions by 50% by 2050 compared with 2005.

[0003] Faced with the dual challenges of energy security and climate change in today's world, countries around the world are actively developing various clean, safe, reliable, sustainable and renewable new energy sources. Traditional fossil energy releases the fixed carbon originally underground in the form of carbon dioxide through combustion or degradation, which directly leads to an increase in carbon emissions in the atmosphere. During the entire life cycle of its production and use, aviation alternative fuels are a process in which carbon from nature enters the biological world through photosynthesis and returns to nature through combustion or degradation. The application of aviation alternative fuels constitutes a carbon cycle chain, thereby reducing carbon emissions throughout the entire life cycle. According to the calculation of the carbon footprint of the fuel throughout its life cycle, aviation alternative fuels can theoretically reduce CO2 emissions by 70% to 80%, which is the only way for the sustainable development of aviation energy.

[0004] At present, the certification of aviation alternative fuels is mainly a drop-in approach, that is, it requires simplicity and ease of use, no changes to airport facilities, aircraft and engine hardware, and can directly replace traditional aviation fuels. Domestic fuel certification mainly refers to two standards: GB 6537-2018 "No. 3 Jet Fuel" and CTSO-2C701 "Civil Aviation Jet Fuel Containing Synthetic Hydrocarbons". Its certification process and methods are similar to ASTM D7566 "Standard Specification for Aviation Turbine Fuels Containing Synthetic Hydrocarbons" and ASTM D4054 "Operational Procedures for Certification and Approval of New Aviation Turbine Fuels and Additives".

[0005] However, the current certification methods for alternative aviation fuels, both domestically and abroad, have the following problems:

[0006] (1) Problem 1: Long fuel certification cycle. Currently, Europe and the United States have formulated a relatively detailed certification specification (ASTM D4054) for alternative aviation fuels. This standard was developed by the American Society for Testing and Materials (ASTM) and can certify the application of new aviation fuels in commercial aircraft. The entire process can be divided into four stages: 1) basic physical and chemical performance test, 2) applicability performance test, 3) component performance test, and 4) whole machine performance test. Any biomass fuel produced by a new process must pass the ASTM D4054 certification process test. After completing the first two stages of testing, it needs to be evaluated by the engine and aircraft OEM. After completing the second and third stages of testing, it also needs to be evaluated again and finally approved. After completing the ASTM D4054 test and approval, the approval process of ASTM D7566 is initiated. The ASTM full committee votes on the SAF (sustainable aviation fuel) specification to be added to ASTM D7566. After passing, the new process will be written into the ASTM D7566 standard. The entire process takes 3 to 5 years, which is a long period of time. It lacks commercial appeal for fuel refining companies and is not conducive to stimulating the research and development of new processes.

[0007] (2) Question 2: The cost of combustion certification testing is high. According to the requirements of the ASTM D4054 standard, an alternative fuel produced by a new process must undergo four stages of testing. Among them, the physical and chemical performance test consumes 40 liters of fuel, the applicability performance test consumes 40 to 400 liters of fuel, the component performance test consumes 950 to 40,000 liters of fuel, and the whole machine performance test consumes at least 850,000 liters of fuel. These consumptions impose a huge burden on fuel producers. Some emerging processes may have great carbon reduction potential and lower production costs, but faced with such a large fuel certification consumption, many refining companies or research institutions will be discouraged.

[0008] (3) Question 3: The third and fourth phases of testing do not specify the test conditions and acceptance criteria. According to the ASTM D4054 standard, component performance tests and whole-machine performance tests are led by engine manufacturers, but the standard does not provide test conditions or acceptable acceptance criteria, making it difficult to certify "ready-to-use" fuels. Although the standard specifies that the original engine manufacturer bears the main safety responsibility and they control the test conditions or acceptable acceptance criteria, they can only be responsible for the safety of the engines they design and manufacture, and whether all engines need to be tested is not clearly stated. For each new fuel refining process, if each model of engine needs to undergo a round of testing, the cost will increase exponentially.

[0009] Therefore, how to provide a set of rapid, unified and optimizable alternative fuel certification solutions for aircraft engines to solve the above problems is a hot topic in current industry research. Summary of the invention

[0010] In order to speed up the certification process of new refining alternative fuels, this application provides a set of rapid certification system for aviation alternative fuels on the basis of ensuring the safety of alternative fuels, thereby shortening the fuel certification cycle, reducing the fuel certification cost, and accelerating the iterative optimization of new refining processes, thereby providing methodological support for promoting the research and development and application of new aviation alternative fuels.

[0011] According to a first aspect of the present application, there is provided a method for certifying alternative aviation fuels, comprising:

[0012] Pre-screening steps include:

[0013] a) prediction of fuel properties based on chemical composition testing;

[0014] b) Key physical and chemical properties test of fuel;

[0015] Preliminary assessment of the physical and chemical properties of the fuel to determine whether the fuel can enter the formal fuel certification process:

[0016] If it is determined that the fuel cannot enter the formal fuel certification process, the refining process of the fuel will be improved accordingly;

[0017] If it is determined that the formal fuel certification process will be initiated:

[0018] Conduct basic fuel performance tests, including:

[0019] 1-A) Conduct physical and chemical performance tests;

[0020] 1-B) Conduct applicability performance tests;

[0021] Conduct fuel performance assessments for engine OEMs, including:

[0022] 2-A) Conduct simulation evaluation of core key indicators;

[0023] 2-B) Carry out verification of key indicators of the model combustion chamber;

[0024] Produce a certification evaluation report I of the fuel according to the test results;

[0025] Determine if additional fuel certification is required:

[0026] If the additional authentication described above is required, then:

[0027] 3) Carry out component performance testing;

[0028] 4) Carry out whole machine performance test;

[0029] According to the test results, a certification assessment report II of the fuel is issued and the safety review step is entered;

[0030] If the additional certification is not required, directly proceed to the security review step;

[0031] Perform a safety review, wherein the safety review determines whether the safety of the fuel has passed the review based on industry specifications and the certification assessment report I or II of the fuel:

[0032] If the inspection is passed, a TSO certificate will be issued;

[0033] If the review is not passed, the certification will be rejected and the refining process of the fuel will be improved accordingly.

[0034] According to a second aspect of the present application, a computer storage medium storing computer executable instructions is provided. When a computer executes the computer executable instructions, the computer executes the aviation alternative fuel method as described in the first aspect.

[0035] According to a third aspect of the present application, a computer system is provided, comprising a device for executing the aviation alternative fuel method as described in the first aspect.

[0036] This Summary is provided to introduce some concepts in a simplified form that are further described below in the Detailed Description. This Summary is not intended to identify key features or essential features of the claimed subject matter, nor is it intended to be used to limit the scope of the claimed subject matter. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] In order to describe the manner in which the above and other advantages and features of the present application can be obtained, a more particular description of the present application, which has been briefly described above, will be presented by reference to specific embodiments of the present application shown in the accompanying drawings. It will be understood that these drawings depict only typical embodiments of the present application and are therefore not to be considered limiting of its scope. The present application will be described and explained with additional specificity and detail through the use of the accompanying drawings, in which:

[0038] Figure 1 An overall schematic flow chart of an aviation alternative fuel certification method according to an embodiment of the present application is shown.

[0039] Figure 2 A schematic flow chart of the two stages 2-A “core key indicator simulation evaluation” and 2-B “model combustion chamber key indicator verification” in an aviation alternative fuel certification method according to an embodiment of the present application is shown.

[0040] Figure 3 A schematic structural diagram of a standard model combustion chamber according to an embodiment of the present application is shown. DETAILED DESCRIPTION

[0041] Before we start the discussion, let's first explain the relevant terms:

[0042] Alternative fuel for aviation is aviation kerosene produced by refining green biomass raw materials such as bio-oil and fiber. Its properties are generally equivalent to those of traditional petroleum-based fuels and it is a fuel that can achieve carbon emission reduction throughout its life cycle.

[0043] Fuel approval process: the entire process by which alternative fuels are approved by the manufacturer after undergoing a series of trials and comprehensive evaluations.

[0044] Key figures of merit (FOM): refers to the key indicators related to the safety performance of the combustion chamber, including ground ignition, high-altitude re-ignition and lean flameout.

[0045] First of all, it should be noted that the purpose of this application is to speed up the certification process of new process refining alternative fuels, shorten the fuel certification cycle, reduce the fuel certification cost, and accelerate the iterative optimization of new refining processes on the basis of ensuring the safety of alternative fuels, thereby providing methodological support for promoting the research and development and application of new aviation alternative fuels.

[0046] In general, the technical solution of this application has the following characteristics:

[0047] (1) Before formally launching alternative fuel certification, a "rapid pre-screening of new process refining alternative fuels" link is set up, and two sub-testing stages are set up in this link. In stage a, only the chemical composition of the new process alternative fuel is tested, and some characteristic parameters of the fuel are predicted through the chemical composition and evaluation model; then, in stage b, the key physical and chemical performance parameters of the new fuel are tested. The parameters obtained in these two stages are used as the basis for judging the fuel characteristics to determine whether the judgment conditions are met. If the conditions are met, the formal fuel certification stage will be entered; if the conditions are not met, the fuel refining process will be improved according to the unsatisfied characteristics.

[0048] (2) After the second stage of the formal fuel certification, a "engine OEM company fuel performance evaluation" link is set up, and two sub-evaluation stages are set up in this link. In the 2-A stage, the safety of the engine using the new process alternative fuel is predicted through simulation and evaluation models, and the engine configuration to be applied and its core key indicators (FOM) are selected as the evaluation object; in the 2-B stage, the impact of the new process alternative fuel on the core key indicators (FOM) is tested through a standard model combustion chamber. The evaluation results obtained in these two stages are used as the basis for judging the safety of the engine. If the judgment conditions are met, the subsequent fuel certification process will be entered; if the conditions are not met, the fuel refining process will be improved according to the unsatisfactory characteristics. In addition, after this process, a judgment link is added. The fuel certification team composed of various stakeholders will decide through review whether the new process fuel needs to enter the third and fourth stages of fuel certification after meeting certain judgment standards; if not, the fuel TSO certificate can be directly issued.

[0049] (3) In the "Engine OEM Fuel Performance Evaluation" link, a representative standard model combustion chamber is designed. The model combustion chamber is representative in civilian engines and is sensitive to fuel characteristic parameters. It can reflect the impact of differences in fuel physical and chemical properties on combustion chamber performance, especially ignition performance. The model combustion chamber designed in this application is a center-staged lean combustion chamber. This type of combustion chamber adopts a two-stage combustion organization form of main combustion stage and pre-combustion stage. The pre-combustion stage adopts rich combustion and uses a nozzle that combines pressure atomization and air atomization for stable combustion; the main combustion stage adopts an air atomization nozzle and lean combustion to control pollutant emissions.

[0050] In order to make the purpose, authentication method and beneficial effects of this application more clearly described, this application is further described in detail below with reference to the accompanying drawings.

[0051] in, Figure 1 Described is an overall schematic flow chart of an aviation alternative fuel certification method designed according to an embodiment of the present application.

[0052] First, assume that a fuel refining enterprise or research institute has newly developed an alternative fuel (also referred to as "fuel") and needs to pass certification. Therefore, for the alternative fuel refined by the new process, a rapid pre-screening of the fuel can be performed first (step 10).

[0053] In step 10, only a small amount of alternative fuel can be used for testing to pre-determine whether the fuel meets the requirements and whether it is qualified for formal certification. As mentioned above, the rapid pre-screening step of the fuel can include two stages a and b.

[0054] In the first stage, the prediction of fuel properties based on chemical component testing is carried out. That is, only the chemical components of the new process alternative fuel are tested, and some characteristic parameters of the fuel are predicted through the chemical components and evaluation models. For example, the chemical components of the alternative fuel can be obtained by testing methods such as two-dimensional gas chromatography (GC×GC), near-infrared absorption spectroscopy (NIR) and nuclear magnetic resonance (NMR), and then the physical and chemical characteristic parameters of the fuel can be predicted using the corresponding chemical components and evaluation models. The chemical components and evaluation models use advanced measuring instruments to obtain molecular and atomic information in the alternative fuel mixture with less fuel consumption, and establish a mapping relationship between these microscopic information and macroscopic physical and chemical information.

[0055] For example, if spectral measurement technology is used, the carbon number distribution of different aviation alternative fuels can be obtained and classified into ten categories according to normal alkanes, isoalkanes, monocyclic alkanes, polycyclic alkanes, aromatic hydrocarbons, etc. The content of each category is used as the independent variable, and the macroscopic physical and chemical parameters, such as density and freezing point, are used as the dependent variable. The carbon number distribution and physical and chemical parameters of a variety of hydrocarbon fuels are collected to establish a training sample set for the model. The corresponding chemical components and evaluation models are established through iterative training. Of course, in addition to spectral measurement technology, other technologies can also be used, but they can all be used through similar processing processes to establish the corresponding chemical components and evaluation models, which will not be explained one by one here.

[0056] Still taking the spectral measurement technology as an example, the carbon number distribution (content of different types of hydrocarbons) of different aviation alternative fuels (containing hundreds of thousands of hydrocarbons) can be obtained and classified. In this embodiment, they are divided into ten categories. The contents of these ten categories are used as inputs of chemical components and evaluation models; and the output of the model is macroscopic physical and chemical parameters, such as density, freezing point, etc. An example description of the relevant prediction parameters and test technology is shown in Table 1 below:

[0057]

[0058]

[0059] Table 1 Examples of fuel property prediction methods based on spectral measurement technology

[0060] Secondly, based on the prediction results of phase a, the key physical and chemical performance parameters of the new fuel are tested. The specific test methods can be referred to the ASTM standards and will not be described in detail here. The fuel consumption in this phase is not large. Table 2 gives an example of the key physical and chemical parameter test:

[0061]

[0062] Table 2 Examples of key physical and chemical performance parameter tests in pre-screening

[0063] It should be understood that Table 1 and Table 2 and the above examples are provided for illustrative purposes only and are not intended to limit the present application thereto. In fact, technicians can use other techniques, such as nuclear magnetic resonance (NMR), etc., to achieve the rapid pre-screening according to their own conditions and needs.

[0064] After completing the prediction of stage a and the experimental test of stage b in the rapid pre-screening step 10, proceed to step 20, in which the physical and chemical properties of the fuel are pre-evaluated to determine whether the new alternative fuel can enter the formal fuel certification process. The evaluation conditions of the relevant parameters can be set with reference to the expected values ​​in Tables 1 and 2, so that it can be determined whether the new alternative fuel can enter the formal fuel certification process based on whether each parameter reaches the expected value. The expected value can be set according to relevant specifications and standards (such as the corresponding requirements in ASTM), which will not be described in detail here.

[0065] If the evaluation conditions are not met, the process may proceed to step 30, where the fuel refining enterprise or research institute may make corresponding improvements to the refining process for the unmet conditions, thereby achieving rapid iteration of new fuel research and development.

[0066] If the evaluation conditions are met, the process may proceed to step 40, from which the process enters the formal certification process of the alternative fuel. In step 40, the basic performance test of the alternative fuel is carried out. The basic performance test of the alternative fuel includes the following two stages:

[0067] Phase 1-A physical and chemical performance tests, including chemical composition, volatility, fluidity, flammability, corrosivity, thermal stability, cleanliness, etc.; and

[0068] The applicability performance tests in Phase 1-B include tests on trace chemical composition, refined distillation range, changes in physical and chemical parameters with temperature, conductivity, filterability, thermal safety, material compatibility and other indicators.

[0069] The two stages of the alternative fuel basic performance test in step 40 can refer to the "basic physical and chemical performance test" and "suitability performance test" mentioned in the aforementioned ASTM standard. Therefore, the specific test items, test methods and index requirements are not described in detail in this application.

[0070] After completing the fuel certification tests in phases 1-A and 1-B, the process will proceed to step 50, where the engine OEM company fuel performance evaluation is carried out. This step mainly includes two stages: 2-A "core key indicator simulation evaluation" and 2-B "model combustion chamber key indicator verification".

[0071] Figure 2The specific evaluation process of these two stages is described in detail. First, the physical and chemical performance data of the alternative fuel after the 1-A and 1-B tests in step 40 are used to construct a combustion reaction mechanism model (step 51) and a nozzle atomization model (step 52).

[0072] Combustion reaction mechanism model: Combustion is a complex system that couples multiple physical and chemical processes such as flow, heat transfer, mass transfer and chemical reaction. In practice, each process must be decoupled to conduct in-depth research on the combustion process. Chemical reaction is one of the control factors of combustion, and plays a vital role in key combustion phenomena such as ignition, flame propagation, flameout, flammable limit, combustion stability, and pollutant emissions. The main task of combustion reaction kinetics is to study chemical reactions in combustion, and to build accurate and reliable combustion reaction kinetic models as the main task. In engineering combustion research, by combining the combustion reaction kinetic model with the combustion numerical simulation research, the combustion characteristics of power equipment such as internal combustion engines and gas turbines can be predicted, thereby providing theoretical guidance for improving their combustion efficiency and controlling pollutant emissions. The combustion chemical reaction process of a complex mixture often includes thousands of reactants and hundreds of thousands of reaction steps. Condensing this process into a few reactants and hundreds of reaction steps is called a concentrated reaction model, which is used to calculate the combustion reaction heat, combustion reaction rate, combustion product production rate, etc. This concentrated reaction model will be integrated into the combustion chamber simulation calculation process and is a sub-model of the simulation model.

[0073] To build such a combustion reaction mechanism model, a large number of basic combustion tests are required to obtain the key parameters in the model. In the past, there was only one type of aviation fuel, and a large number of tests were acceptable. However, there are many types of alternative aerospace fuels, and a large number of tests are unrealistic. For this reason, this program divides the combustion reaction of these hydrocarbon fuels into two steps, the first step is pyrolysis, and the second step is oxidative cracking. The first step uses a unified 7-step reaction formula, and the parameters in the reaction formula need to be measured in basic experiments; the second step mainly involves reactions below C4 (carbon molecules and carbon ions with less than 4 carbon atoms), which have reaction databases available, and most fuels are similar. This greatly reduces the amount of repeated experiments. It is equivalent to building a "paradigm" for alternative fuel reaction models.

[0074] Specifically, in step 51, the HyChem method can be used to construct a combustion reaction mechanism model. Since the macromolecules in the combustion reaction are first cracked, and then cracked into small molecules below C4 for chemical reactions, two methods can be used to respectively deal with the reactions of large and small molecules. This method is called the HyChem method. It unifies the form of hydrocarbon fuel reaction mechanisms, and has a high degree of simplicity and accuracy, and can be used as a reference for key technologies of simplified reaction mechanisms of sustainable aviation fuels. The HyChem method can solve the difficulties of inconsistent fuel component mechanism forms and difficulty in direct merging in proxy models. By using the 7-step cracking mechanism database of fuel components established in advance by the HyChem method, combined with a simplified small molecule oxidation core mechanism and a fast proxy model construction method, an efficient, streamlined and accurate construction of a simplified chemical reaction mechanism of sustainable aviation fuels can be achieved, providing support for the simulation of key performance of the combustion chamber in subsequent steps.

[0075] Nozzle atomization model: It is a semi-empirical formula that can predict the nozzle atomization parameters such as atomization angle, droplet statistical particle size, droplet velocity, nozzle flow rate, etc. under different fuels, different nozzle structures, and different working conditions. These parameters are the necessary input parameters for combustion chamber simulation calculations.

[0076] Specifically, in step 52, a nozzle atomization model is established in combination with the physical and chemical performance parameters of the alternative fuel and the nozzle atomization model is used to predict the nozzle atomization performance, including droplet size distribution, droplet velocity distribution, atomization angle, etc. Optical testing methods can also be used to conduct atomization performance tests on specific combustion chamber nozzles to obtain the above atomization performance parameters. These model-predicted or experimentally measured parameters will serve as input parameters for subsequent simulations.

[0077] The above two steps will provide models and data parameters for the simulation of ignition and lean flameout.

[0078] In the subsequent step 53, the cellular automaton method is used to simulate the combustion chamber ignition process. In view of the difficulty that the simulation methods of the full-ring combustion chamber ignition process are very different and time-consuming, in this step, the cellular automaton and random particle tracking method are used to carry out a three-dimensional non-steady-state simulation of ignition. This technology combines the time-averaged mixed field simulation of the combustion chamber, the cellular automaton and the random particle tracking method, and quickly simulates the ignition flame process by calculating the spatial random motion of the fire core and its interaction with the combustible cells in the combustion chamber, and obtains the probability of successful ignition flame, which can quickly evaluate the combustion chamber ignition performance, ignition boundary oil-gas ratio and other parameters.

[0079] Cellular automata and random particle tracking combine combustion chamber simulation calculation, cellular automata, random particle tracking and Monte Carlo simulation, which is an efficient three-dimensional non-steady-state simulation method for the ignition process. The simulation is divided into three steps: (1) Based on the time-averaged results of the three-dimensional cold simulation of the combustion chamber, the probability density distribution function of the flow velocity and components in the combustion chamber is obtained; (2) The flow field area in the combustion chamber is divided according to the requirements of cellular automata (one area is a cell), and the flammability of the cell is judged based on the flammable limit; (3) The initial fire core model is used to initialize the flame example in the calculation area, and the random particle tracking method is used to simulate the particle motion process, and information is exchanged with the cell grid to simulate the flame propagation process.

[0080] Next, in step 54, a large eddy simulation (LES) method is used to predict the lean burnout process of the combustion chamber. Specifically, the LES simulation calculation of the combustion chamber is carried out in combination with the physical and chemical performance data of the alternative fuel, and the combustion reaction mechanism model and the nozzle atomization model established in steps 51 and 52.

[0081] Large Eddy Simulation (LES): This is a high-order method in combustion chamber simulation calculations. It has high requirements for computing resources and takes a long time to calculate, but it can calculate the three-dimensional non-steady-state process of combustion. This invention uses this method to calculate the flameout process of the combustion chamber, and can evaluate whether the combustion chamber will flameout on the flameout boundary after changing the fuel.

[0082] For example, in the initial calculation, the slow-running condition of the engine is used as the initial condition of the simulation calculation, and the oil-gas ratio is kept unchanged (generally between 0.095 and 0.15); after every 40 to 60 ms of the calculated physical time, the oil-gas ratio is reduced by 0.005; the calculation is then stabilized for another 40 to 60 ms, and the oil-gas ratio is further reduced until the flame becomes obviously unstable and flames out; the oil-gas ratio at this moment is the lean flameout oil-gas ratio predicted by the simulation.

[0083] After completing the above preparations, the engine OEM company's fuel performance evaluation began.

[0084] First, in step 55, a core key indicator simulation evaluation is performed.

[0085] Specifically, the OEM company uses the combustion chamber of the alternative fuel target application engine as the object of simulation calculation, and conducts simulation calculation for key core indicators, namely ground ignition performance, high-altitude ignition performance and lean flameout performance. Among them, the ground ignition performance and high-altitude ignition performance are calculated and analyzed using the method in step 53, while the lean flameout performance is simulated and predicted using the method in step 54.

[0086] Then, in step 56, an assessment test of the effect of alternative fuels on the core key indicators of the combustion chamber is carried out based on a standard model combustion chamber. Figure 3 As shown in the figure, the standard model combustion chamber can be designed as a center-staged lean combustion chamber. This type of combustion chamber is generally representative in civil engines. It adopts a two-stage combustion organization form of main combustion stage and pre-combustion stage. The pre-combustion stage adopts rich combustion and uses a nozzle combining pressure atomization and air atomization for stable combustion; the main combustion stage adopts an air atomization nozzle and lean combustion to control pollutant emissions. This model combustion chamber uses a single head to carry out the test, and the demand for fuel is relatively small. The core key indicators in Table 3 are mainly evaluated, and the test conditions are shown in Table 3. The point-to-blank boundary oil-gas ratio measured in the test will be compared with the test results using traditional aviation kerosene. The deviation must meet certain conditions. The expected value in Table 3 can be referred to.

[0087]

[0088]

[0089] Table 3. Inlet conditions for the core key index assessment test of the model combustion chamber

[0090] **Note: The expected value actually represents the deviation of the flameout fuel-to-air ratio measured with alternative fuels from the fuel-to-air ratio measured with traditional aviation kerosene, where:

[0091]

[0092] Φ represents the oil-gas ratio.

[0093] LBO stands for lean blow-off condition.

[0094] C_Ign represents the ignition condition at ground level.

[0095] HA_Ign means ignition under high altitude conditions.

[0096] It should be understood that Table 3 and the above examples are provided for illustrative purposes only and are not intended to limit the present application thereto. In fact, technicians can adapt the parameters and processes to achieve the above operations according to their own conditions and needs.

[0097] After completing the above fuel certification test and evaluation, the process proceeds to step 60. In this step, a certification evaluation report I of the alternative fuel is issued based on the above test results.

[0098] Then, the process proceeds to step 70, in which there is an additional determination link, namely, whether additional certification of the alternative fuel is required. In this determination, if the alternative fuel has little effect on the core key indicators of the combustion chamber, and the parameters and configurations of the combustion chamber of the target application engine and the model combustion chamber are not much different, it is determined that there is no need to carry out the additional certification test in step 80, and the process directly proceeds to step 100 to conduct a final safety review based on the certification assessment report I of the alternative fuel. Otherwise, the process needs to proceed to step 80 to perform additional certification tests.

[0099] For example, assuming that the new alternative fuel has been tested in a lean combustion chamber but not in a rich combustion chamber, and in the future the new fuel will be mainly used in engines with rich combustion chambers, then the additional determination will determine that the new alternative fuel still needs to undergo additional tests in stages 3 and 4, and the process enters step 80.

[0100] In step 70, if it is determined that additional certification tests of the fuel are required, the process enters step 80 to carry out verification tests of the third and fourth stages. The verification test of the third stage is a component performance test, while the verification test of the fourth stage is a whole machine performance test. Among them, the component performance test includes: thermal shock test of turbine blades (corrosive assessment of coatings and blades by alternative fuel combustion products), fuel system performance test (nozzle atomization, fuel icing, filter blockage, control performance, etc.), full-ring combustion chamber performance test (lean oil flameout, ground ignition, high-altitude ignition, combustion efficiency, outlet temperature distribution, pollutant emissions, fuel coking, etc.), AUP performance test (ground ignition, high-altitude ignition assessment), etc.; the whole machine performance test includes: whole machine durability test (at least 150 hours, at least 450 cycles, each cycle lasting 15 to 20 minutes) and whole machine performance test (such as thrust, fuel consumption rate, lean oil flameout boundary, ignition envelope and combustion oscillation in transition state, etc.).

[0101] As mentioned above, the ASTM certification process also includes component performance testing and whole machine performance testing. Therefore, the specific test items, test methods and index requirements of these tests are no longer described in detail in this application.

[0102] After all the above fuel certification tests and evaluations are completed, a certification evaluation report II of the alternative fuel is issued in step 90 , and then the process enters step 100 .

[0103] In step 100, whether the alternative fuel has passed the safety certification is examined based on the certification evaluation report I or II.

[0104] The safety review can be implemented through a certification review module. The certification review module determines whether the safety of the alternative fuel has passed the review by combining relevant industry specifications and the fuel certification assessment report I or II. If the conditions are met (for example, the requirements of industry specifications are met, such as ASTM), the review is passed and the process proceeds to step 110 to issue a TSO certificate for the alternative fuel. If the conditions are not met, the certification is rejected and the process returns to step 30. The relevant fuel refining enterprise or research unit can analyze the content of the rejection notice in order to make further improvements to the fuel refining process.

[0105] In a preferred embodiment, the certification review module can be replaced by a certification review team jointly formed by the OEM and an official authority (for example, in China, the agency is the Certification Center of the Civil Aviation Administration of China). That is, the certification review team manually evaluates the safety of alternative fuels. Manual evaluation can more flexibly and proactively discover various problems in the report, and therefore has better safety.

[0106] When the safety review is passed, the process proceeds to step 110 to issue a TSO certificate for the alternative fuel.

[0107] It should be understood that the examples, parameters, conditions, limits, etc. involved in the above-mentioned scheme are only given for the purpose of illustration and are not intended to limit the present application thereto. In fact, technicians can make adaptive modifications to the above-mentioned scheme according to their own conditions and needs to implement the above-mentioned scheme.

[0108] Beneficial effects:

[0109] (1) This application sets a pre-screening link before the formal certification of the new process alternative fuel, mainly using two-dimensional gas chromatography, near-infrared absorption spectroscopy and nuclear magnetic resonance testing methods to obtain the chemical composition of the new process alternative fuel, and then predict the characteristics of the fuel. The fuel required for this stage of testing is only 1 to 10 ml; at the same time, some key physical and chemical parameters are measured to conduct a preliminary assessment of the safety of the fuel. The fuel required for this stage is also only 150 to 300 ml. Through this pre-screening link, the optimization, iteration and evaluation efficiency of new fuels and new processes can be accelerated, and the certification cost and risk can be reduced; at the same time, it is also conducive to stimulating fuel refining companies to actively develop new processes for alternative fuels with low refining costs and large carbon reduction.

[0110] (2) This application sets up an OEM evaluation link after the second stage of fuel certification, which mainly uses simulation analysis, model prediction and other methods to evaluate the impact of new process fuels on the key performance of the engine to be used; at the same time, with the help of experimental tests on standard model combustion chambers, the impact of fuels on the core key performance of the engine is evaluated; and then provide an evaluation basis for whether to conduct third and fourth stage tests. Through this OEM evaluation link, the certification process of new process alternative fuels can be accelerated and the cost of fuel certification can be reduced; at the same time, the applicability of fuel evaluation and certification methods can be expanded to avoid the problem of repeated certification when the same new fuel is used in different engines.

[0111] Although different embodiments are described above, it should be understood that they are intended to be exemplary rather than limiting. Those skilled in the relevant art(s) will appreciate that various modifications may be made in form and detail without departing from the spirit and scope of the present application as defined in the appended claims. Therefore, the breadth and scope of the present application disclosed herein should not be limited by the exemplary embodiments disclosed above, but should only be defined in accordance with the appended claims and their equivalents.

Claims

1. A method for certifying alternative aviation fuels, comprising: Pre-screening steps include: a) prediction of fuel properties based on chemical composition testing; b) Key physical and chemical properties test of fuel; Preliminary assessment of the physical and chemical properties of the fuel to determine whether the fuel can enter the formal fuel certification process: If it is determined that the fuel cannot enter the formal fuel certification process, the refining process of the fuel will be improved accordingly; If it is determined that the formal fuel certification process will be initiated: Conduct basic fuel performance tests, including: 1-A) Conduct physical and chemical performance tests; 1-B) Conduct applicability performance tests; Conduct fuel performance assessments for engine OEMs, including: 2-A) Conduct simulation evaluation of core key indicators; 2-B) Carry out verification of key indicators of the model combustion chamber; Produce a certification evaluation report I of the fuel according to the test results; Determine if additional fuel certification is required: If the additional authentication described is required, then: 3) Carry out component performance testing; 4) Carry out whole machine performance test; According to the test results, a certification assessment report II of the fuel is issued and the safety review step is entered; If the additional certification is not required, proceed directly to the final review step; Perform a safety review, wherein the safety review determines whether the safety of the fuel has passed the review based on industry specifications and the certification assessment report I or II of the fuel: If the safety review is passed, a TSO certificate will be issued; If the safety review fails, the certification will be rejected and the refining process of the fuel will be improved accordingly.

2. The aviation alternative fuel certification method according to claim 1, characterized in that: The safety review may be performed by a certification review module or a certification review team jointly formed by the OEM and an official authority.

3. The aviation alternative fuel certification method according to claim 1, characterized in that: The a) fuel property prediction based on chemical component testing includes: obtaining the chemical components of the fuel by means of two-dimensional gas chromatography GC×GC, near infrared absorption spectroscopy NIR and nuclear magnetic resonance NMR testing, and then predicting the physical and chemical property parameters of the fuel by using the corresponding chemical components and evaluation models.

4. The aviation alternative fuel certification method according to claim 1, characterized in that: in The said core key indicator simulation evaluation means that the OEM company uses the fuel target engine combustion chamber as the object of simulation calculation, and conducts simulation calculation for the ground ignition performance, high altitude ignition performance and lean flameout performance among the key core indicators; The said verification of key indicators of the model combustion chamber refers to: conducting an assessment test of the impact of fuel on the core key indicators of the combustion chamber based on a standard model combustion chamber.

5. The aviation alternative fuel certification method according to claim 4, characterized in that: The standard model combustion chamber is designed as a center-staged lean combustion chamber, which is widely representative in civilian engines. It adopts a two-stage combustion organization form of a main combustion stage and a pre-combustion stage. The pre-combustion stage adopts rich combustion and uses a nozzle that combines pressure atomization and air atomization for stable combustion; the main combustion stage adopts an air atomization nozzle and uses lean combustion to control pollutant emissions.

6. The aviation alternative fuel certification method according to claim 1, characterized in that: Fuel performance assessments for engine OEMs also include: Using the physical and chemical property data of the fuel obtained after 1-A) conducting physical and chemical property tests and 1-B) conducting applicability performance tests, a combustion reaction mechanism model and a nozzle atomization model are constructed; The cellular automaton method is used to simulate the combustion chamber ignition process; Large eddy simulation (LES) is used to predict the lean blowout process in the combustion chamber.

7. The aviation alternative fuel certification method according to claim 6, characterized in that: in The combustion reaction mechanism model is constructed using the HyChem method; The cellular automaton method combines the time-averaged mixed field simulation of the combustion chamber, the cellular automaton and the random particle tracking method, and quickly simulates the ignition and flame-linking process by calculating the spatial random motion of the fire core and its interaction with the combustible cells in the combustion chamber to obtain the success probability of the ignition and flame-linking.

8. The aviation alternative fuel certification method according to claim 1, characterized in that: The determination of whether additional certification of the fuel is required includes: if the fuel has little effect on the core key indicators of the combustion chamber, and the parameters and configurations of the combustion chamber of the target application engine and the model combustion chamber are not much different, then it is determined not to carry out the additional certification; otherwise, the additional certification is carried out.

9. A computer storage medium storing computer executable instructions, which, when executed by a computer, enables the computer to perform the aviation alternative fuel certification method according to claims 1-8.

10. A computing system comprising means for executing the aviation alternative fuel certification method as claimed in claims 1-8.

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