Rapid evaluation and calculation method for performance of precooler of cryogenic combined cycle engine

Abstract

The invention discloses a rapid evaluation and calculation method for the performance of a precooler of a cryogenic combined cycle engine, and the method comprises the steps: rapidly and accurately estimating the average performance parameter of an outlet of the precooler, the size and weight of the precooler and other comprehensive design parameters during the calculation of the overall performance of the cryogenic combined cycle engine; and support is provided for later construction of a high-precision complete machine component-level transformation specific heat performance calculation model. After an average parameter is obtained through the precooler, the precooler can serve as a conventional engine component and is substituted into a whole machine performance model, and the accurate overall performance of the engine is obtained.

Description

Technical Field

[0001] The invention belongs to the field of aviation technology, and in particular relates to a method for quickly evaluating the performance of a precooler of a cryogenic combined cycle engine. Background Art

[0002] The strategic value of the space economy is gaining increasing attention worldwide. However, the technologies for hypersonic flight and low-cost space access are still immature, so many plans and proposals for this economy remain at a hypothetical stage. Hypersonic aircraft and reusable space launch vehicles are crucial. Half a century after the concept of hypersonic flight was proposed, hypersonic near-space vehicles have shown broad application prospects and enormous military and civilian value.

[0003] The Deeply Precooled Combined Cycle Engine (DCE) is a new engine concept featuring a wide speed range, excellent thrust performance across the entire speed range, and high system utilization. It represents a highly promising Ma0-5+ wide-speed combined cycle propulsion system, promising to enable hypersonic flight missions and horizontal takeoff and landing into orbit. This new propulsion system offers new insights into the development of wide-speed combined cycle propulsion and also introduces new technical challenges to its research. The precooler is a crucial component of the CCE. Located after the engine inlet, it cools incoming air from 1250K to 1000K in 0.01s.

[0004] The operating principle of the CCE is similar to the SABRE-3 concept announced by the UK-based REL company. The CCE utilizes a closed helium precooling cycle system, precooling the incoming air with a high-pressure helium precooler. Precooling the incoming air during the mode transition process not only avoids contamination of the coolant with the air, but also addresses the "thrust gap" issue, resulting in increased safety. The CCE utilizes the adjustable geometry of the outer nozzle to achieve optimal transitions between different modes, extending the operating speed range and operating range. The basic principle of the CCE precooler is similar to the design of natural gas exchangers in biological systems. Similar to fish gills, the heat exchanger utilizes a large number of very low-pressure-loss manifolds connected by a very short and compact matrix of high-performance tubes. Rapid heat transfer through this matrix makes the precooler practical in CCEs.

[0005] This type of precooler utilizes a novel, compact, cylindrical structure with a modular design. Multiple heat exchange tube bundles extend outward from the precooler's inner diameter in the form of an Archimedean spiral. Complete helium flow tubes are connected to the inlet header to form a precooler module. Multiple complete precooler modules are distributed circumferentially to form a complete precooler. Each precooler module consists of multiple rows of staggered, thin-walled microtubes, with the tube bundles arranged in a staggered pattern.

[0006] Figure 1 The schematic diagram of the single module structure of the precooler is shown;

[0007] The main view of the precooler is as follows Figure 2 As shown;

[0008] Figure 3 The arrangement of the microtubules in the precooler is given, where s1d0 and s2d0 are the transverse and longitudinal spacings between adjacent tubes, and d0 is the outer diameter of the microtubule.

[0009] This design can not only ensure the consistency of the circumferential and radial spacing of the micro-tube bundles, but also realize the countercurrent heat exchange between the internal heat exchange medium and the external air, which not only improves the space utilization, but also reduces the temperature difference between the internal and external heat exchange fluids, which is conducive to improving the heat exchange efficiency. Summary of the Invention

[0010] To overcome the shortcomings of existing technologies, the present invention provides a rapid performance evaluation and calculation method for cryogenic combined-cycle engine precoolers. This method rapidly and accurately estimates average precooler outlet performance parameters and comprehensive design parameters such as precooler dimensions and weight when calculating the overall performance of a cryogenic combined-cycle engine. This method also supports the subsequent construction of a highly accurate component-level variable specific heat performance calculation model for the entire engine. By calculating the average parameters, the precooler can be treated as a regular engine component and incorporated into the overall engine performance model to obtain a more accurate estimate of overall engine performance.

[0011] The technical solutions adopted by the present invention to solve the technical problems are as follows:

[0012] Step 1: Given the engine operating altitude H, Mach number Ma and engine mass flow rate W a , the total temperature T at the inlet of the air path precooler is obtained by the variable specific heat calculation method in,h , Total pressure P at the inlet of air flow path precooler in,h ; The air flow path precooler inlet mass flow W is calculated based on the flow ratio entering the core flow path in,h According to the required temperature drop of the engine cooling high temperature incoming air, the total temperature T of the precooler air flow outlet is obtained out,h According to the law of flow conservation, the mass flow rate W of the precooler air flow outlet is obtained out,h ;

[0013] Step 2: Use the precooler geometric design parameters given by the design point: precooler inner diameter r i , the central angle β0 of the helium fine flow tube of a single module of the precooler, and the length Lfc of a single fine flow tube of the precooler are calculated using the Archimedean spiral arc length formula; the equation of the Archimedean spiral in polar coordinates is expressed as:

[0014] r=a+bβ,0≤β≤β0

[0015] a=r i , b=sa / 2π

[0016] s a =s2×d0×N tm ×N t

[0017] Where a is the polar diameter, β is the polar angle, r is the precooler radius, s a is the pitch between modules, d0 is the outer diameter of the precooler fine flow tube, s2*d0 is the longitudinal spacing of the fine flow tube, N tm is the number of precooler modules, N t is the number of tube rows in a single module of the precooler, β0 is the central angle of the fine flow tube, s2 is the ratio of the longitudinal spacing of the fine flow tube to the outer diameter of the fine flow tube of the precooler;

[0018] The differential expression of pipe length is:

[0019]

[0020] Integrate to get the length of the micro flow tube:

[0021]

[0022] Precooler outer diameter:

[0023] r o =r i +s a / 2π×β0

[0024] Then, according to the inner diameter d of the microtube i , outer diameter d0, tube length Lfc and material density ρ tube Calculate the volume V of a single microtubule t_single With mass m t_single , and then according to the number of precooler modules N tm 、Number of tube rows in a single module of precooler t And the number of axial tubes N a Calculate the total number of microtubules N t_all , total mass of precooler m all , the total volume of the precooler tube V t_all , total volume of precooler V allAnd the total length of the precooler, that is, the axial length Lpc:

[0025]

[0026] m t_single =ρ tube V t_single

[0027] N t_all =N tm ×N t ×N a

[0028] m all =N t_all ×m t_single

[0029] V t_all =V t_single ×N t_all

[0030] Lpc=(s1-1)×d0×N a

[0031]

[0032] Where s1 is the ratio of the lateral spacing of the fine flow tubes to the outer diameter of the fine flow tubes of the precooler;

[0033] At the same time, calculate the heat transfer area A h :

[0034] A h =πd0×Lfc×N t_all

[0035] Step 3: Simplify the precooler model heat transfer limit T according to the engine design point limit Calculate the total temperature T of the cold flow outlet of the precooler out,c , total temperature of cold flow inlet of precooler T in,c and the total pressure of the cold flow inlet of the precooler P in,c Transfer parameters calculated for closed helium cycle compressor components; by energy conservation, Q in =Q out , the heat absorption and heat release are equal, combined with the physical properties of air and helium, the mass flow rate W of the cold flow inlet of the precooler is obtained in,c :

[0036]

[0037] Where C p_air and C p_He are the specific heats of air and helium at constant pressure, respectively;

[0038] Then calculate the qualitative temperature T of the high temperature side of the precooler according to the inlet and outlet temperatures of the high and low temperature sides h,average , qualitative temperature T on the low temperature side of the precooler c,average :

[0039]

[0040] The high temperature side temperature T h,average and the total inlet pressure P in,h The physical parameters of the high-temperature side fluid air, dynamic viscosity μ, are calculated by interpolation from the database published by NIST. h , thermal conductivity λ h and the Prandtl number Pr h ;

[0041] The Reynolds number of the high temperature side fluid is calculated using the Reynolds number calculation formula. h :

[0042]

[0043] Where ρ, v, and d represent the fluid density, flow velocity, and flow channel diameter, respectively, and μ represents the dynamic viscosity of the fluid;

[0044] The low temperature side qualitative temperature T c,average and the total inlet pressure P in,c The physical parameters of the low-temperature side fluid helium, dynamic viscosity μ, are calculated by interpolation from the database published by NIST. c , thermal conductivity λ c and the Prandtl number Pr c ;

[0045] The Reynolds number of the low temperature side fluid is calculated using the Reynolds number calculation formula. c :

[0046]

[0047] Given the initial value of the ratio of the cold flow gas thermal resistance to the total thermal resistance, the wall temperature T w for:

[0048]

[0049] Where Rc is the cold flow thermal resistance, R is the total thermal resistance;

[0050] Through the wall temperature T w and the total inlet pressure P in,h The wall fluid Prandtl number Pr is calculated by interpolation from the database published by NIST w For the high-temperature side fluid, the Nusselt number Nu of the high-temperature side fluid is obtained using the Zhukauskas cross-cross tube number correlation formula h :

[0051]

[0052] At this time, calculate the convection heat transfer coefficient h of the high temperature side fluid h With Stanton Number St h :

[0053]

[0054] For the low-temperature fluid side, the Nusselt number Nu of the low-temperature side fluid is obtained using the Gnielinski formula for turbulent forced convection heat transfer in the tube groove. c :

[0055]

[0056] Where f is the Darcy drag coefficient of turbulent flow in the tube, according to the Filonenko formula:

[0057] f=(1.82×lgRe c -1.64) -2

[0058] For gas:

[0059]

[0060] Among them, c t Indicates the temperature difference correction coefficient, T c Indicates the average temperature of the fluid on the low temperature side;

[0061] At this time, calculate the convective heat transfer coefficient h of the low temperature side fluid c With Stanton Number St c ;

[0062] Then calculate the cold flow thermal resistance R c 、Heat flow thermal resistance R h , pipe wall thermal resistance R w , total thermal resistance R and total heat transfer coefficient k of the precooler:

[0063]

[0064] Then, substitute the obtained parameters into the wall temperature calculation again and repeat step 3 to correct the qualitative parameters;

[0065] Step 4: Use the heat transfer unit number method to calibrate the precooler based on the heat transfer value Φ1 and calculate the actual outlet temperature:

[0066] φ1=(q m c) min (T in -T out )max =η(q m c) min (T in,h -T in,c )

[0067] Where (q m c) min is the value on the side with smaller heat capacity flow rate, (T in -T out ) max is the maximum temperature difference that may occur in the precooler, η is the precooler efficiency; T in 、T out represent the fluid inlet temperature and outlet temperature respectively;

[0068] The heat transfer coefficient k and heat transfer area A obtained above h And the temperature drop Δt given by the design point, we can get contrast Is it consistent with Q in step 3? in If they are not equal, repeat steps 2 to 4 using the pipe length Lfc as a variable, perform iterative solution, and calculate the actual outlet temperature. At the same time, correct the pipe length Lfc calculated during design to give the final pipe length.

[0069] Repeat step 2 to recalculate the corrected tube length Lfc and the volume V of a single microtubule. t_single With mass m t_single , total mass of precooler m all , the total volume of the precooler tube V t_all , total volume of precooler V all , and calculate the heat transfer area A outside the tube h_out 、Heat exchange area in the tube A h_in and the heat exchange effectiveness of the precooler ε;

[0070] Step 5: Use the SEHaaland formula to calculate the friction loss f in the tube. c calculate:

[0071]

[0072] Where k d is the roughness inside the tube;

[0073] The dynamic pressure loss caused by the flow in the precooler tube is:

[0074]

[0075] Where, v c represents the flow rate of the fluid on the low temperature side, ρ c represents the density of the fluid on the low temperature side;

[0076] For the flow resistance calculation of the high-temperature side fluid, the friction loss fh in the tube is calculated:

[0077]

[0078] The dynamic pressure loss caused by the high-temperature fluid flow outside the precooler tube is:

[0079]

[0080] Where, ρ h represents the density of the fluid on the high temperature side, v h Indicates the fluid flow rate on the high-temperature side;

[0081] At this time, the total pressure P at the hot flow outlet of the precooler is calculated out,h , total pressure of cold stream outlet P out,c And the total pressure on the high temperature side of the precooler is restored Σ h , low temperature side total pressure recovery Σ c ;

[0082] P out,h =P in,h -P lost,h ;P out,c =P in,c -P lost,c

[0083]

[0084] At this point, the performance parameters and structural parameters of the inlet and outlet of the high and low temperature sides of the precooler have been obtained, and the calculation is completed.

[0085] Preferably, the cold flow gas is helium.

[0086] A computer program enables a computer to execute the above-mentioned rapid evaluation calculation method.

[0087] An electronic device includes: a processor and a memory; the memory is used to store a computer program, and the processor is used to execute the computer program stored in the memory, so that the electronic device performs the above-mentioned rapid evaluation calculation method.

[0088] A computer-readable storage medium stores a computer program, which implements the above-mentioned rapid evaluation calculation method when executed by a processor.

[0089] A chip includes: a processor for calling and running a computer program from a memory, so that a device equipped with the chip executes the above-mentioned rapid evaluation calculation method.

[0090] A computer program product includes a computer storage medium storing a computer program, wherein the computer program includes instructions executable by at least one processor, and when the instructions are executed by the at least one processor, the above-mentioned fast evaluation calculation method is implemented.

[0091] The beneficial effects of the present invention are as follows:

[0092] The purpose of the present invention is to replace the traditional zero-dimensional simplified calculation model with a structure-performance calculation method when calculating the overall performance of a cryogenic combined cycle engine. This method helps overall performance designers quickly determine and accurately estimate comprehensive design parameters such as the average performance parameters at the precooler outlet and the precooler's dimensions and weight. This method shortens the overall design iteration cycle, improves design efficiency, enhances evaluation rationality and calculation accuracy, and provides support for the subsequent construction of a high-precision component-level variable specific heat performance calculation model. After determining the average parameters using the former, the precooler can be treated as a conventional engine component and incorporated into the overall engine performance model to obtain a more accurate overall engine performance. BRIEF DESCRIPTION OF THE DRAWINGS

[0093] Figure 1 This is a schematic diagram of the single module structure of the precooler;

[0094] Figure 2 This is the axial main view of the precooler;

[0095] Figure 3 This is the arrangement of fine tubes in the precooler;

[0096] Figure 4 This is a flow chart for calculating the performance of a cryogenic combined cycle engine;

[0097] Figure 5 Flowchart for the calculation of a rapid performance evaluation method for a cryogenic combined cycle engine precooler.

[0098] Reference numerals: 1 - precooler manifold, 2 - fine flow tube, 3 - fine flow tube inlet, 4 - fine flow tube bundle, 5 - fine flow tube outlet. DETAILED DESCRIPTION

[0099] The present invention will be further described below with reference to the accompanying drawings and examples.

[0100] This invention proposes a rapid performance evaluation and calculation method for a cryogenic combined cycle engine precooler. This method aims to quickly and accurately estimate the average performance parameters at the precooler outlet and comprehensive design parameters such as the precooler's dimensions and weight when calculating the overall performance of a cryogenic combined cycle engine. This method also supports the subsequent construction of a highly accurate component-level variable specific heat performance calculation model for the entire engine. By calculating the average parameters, the precooler can be treated as a conventional engine component and incorporated into the overall engine performance model to obtain a more accurate estimate of the engine's overall performance. The precooler is a crucial component in a cryogenic combined cycle engine and is not a common component in traditional aircraft engines. Therefore, the precooler calculation model in current component-level zero-dimensional steady-state calculation models is extremely simplified and fails to reflect the physical and structural parameters of the fluid flow within the precooler. Furthermore, in multidimensional calculation models, the precooler is a computationally intensive and complex component, making it unsuitable for inclusion in component-level steady-state calculation models. Therefore, a rapid performance evaluation and calculation method for cryogenic combined-cycle engine precoolers is urgently needed. This method, replacing the traditional zero-dimensional simplified calculation model with a structure-performance approach, can help overall performance designers quickly determine whether performance meets requirements, shorten the overall design iteration cycle, improve design efficiency, and ultimately enhance the rationality of evaluations and calculation accuracy. Precoolers can cool the total temperature of the incoming airflow to extremely low temperatures, effectively reducing the thermal degradation of the compression components caused by high-temperature incoming airflow, such as reduced efficiency, lower pressure ratio, and reduced converted speed and flow. This can improve the compressor's design pressure ratio, further enhancing engine fuel economy, and increasing engine thrust and specific impulse.

[0101] (1) The working fluids in the precooler include air and helium. In the calculation, the constant pressure specific heat of the air working fluid C p The physical properties such as specific heat ratio k, enthalpy value h, entropy S are calculated by the CEA (Chemical Equilibrium Application) software published by NASA (National Aeronautics and Space Administration). p Various physical properties such as specific heat ratio k, enthalpy value h, entropy S, etc. are obtained by querying and calculating from the reference fluid thermodynamic and transport characteristics database published by NIST (National Institute of Standards and Technology);

[0102] (2) The precooler is made of nickel-based high-temperature alloy GH4169. The thermal conductivity λ, density ρ and other material properties used in the calculation are obtained from the China Aviation Materials Handbook published by China Standards Press.

[0103] The present invention aims to provide a method for rapidly and accurately evaluating the performance parameters of a cryogenic combined cycle engine precooler outlet and its comprehensive design parameters, such as dimensions and weight. To achieve this objective, the present invention employs a method for rapidly evaluating the performance of a cryogenic combined cycle engine precooler, comprising the following steps:

[0104] Step 1: Given the engine operating altitude H, Mach number Ma and engine flow mass flow W a , the total temperature T at the inlet of the air path precooler is obtained by the variable specific heat calculation method in,h , Total pressure P at the inlet of air flow path precooler in,h , the air flow path precooler inlet mass flow W is calculated based on the flow ratio entering the core flow path in,h According to the required temperature drop of the engine cooling high temperature incoming air, the total temperature T of the precooler air flow outlet is obtained out,h According to the law of flow conservation, the mass flow rate W of the precooler air flow outlet is obtained out,h .

[0105] Step 2: Use the precooler geometric design parameters given by the design point to determine the inner diameter of the precooler r. i , the central angle β0 of the helium fine flow tube of a single module of the precooler, and the length Lfc of a single fine flow tube of the precooler are calculated using the Archimedean spiral arc length formula;

[0106] The equation of the Archimedean spiral in polar coordinates is:

[0107] r=a+bβ,0≤β≤β0

[0108] a=r i , b=sa / 2π

[0109] s a =s2×d0×N tm ×N t

[0110] Where a is the polar diameter, β is the polar angle, r is the precooler radius, s a is the pitch between modules, d0 is the outer diameter of the precooler fine flow tube, s2*d0 is the longitudinal spacing of the fine flow tube, N tm is the number of precooler modules, N t is the number of tube rows in a single module of the precooler, β0 is the central angle of the fine flow tube, s2 is the ratio of the longitudinal spacing of the fine flow tube to the outer diameter of the fine flow tube of the precooler;

[0111] The differential expression of pipe length is:

[0112]

[0113] Integrate to get the length of the micro flow tube:

[0114]

[0115] Precooler outer diameter:

[0116] r o =r i +s a / 2π×β0

[0117] Then, according to the inner diameter d of the microtube i , outer diameter d0, tube length Lfc and material density ρ tube Calculate the volume V of a single microtubule t_single With mass m t_single , and then according to the number of precooler modules N tm 、Number of tube rows in a single module of precooler t And the number of axial tubes N a Calculate the total number of microtubules N t_all , total mass of precooler m all , the total volume of the precooler tube V t_all , total volume of precooler V all And the total length of the precooler, that is, the axial length Lpc:

[0118]

[0119] m t_single =ρ tube V t_single

[0120] N t_all =N tm ×N t ×N a

[0121] m all =N t_all ×m t_single

[0122] V t_all =V t_single ×N t_all

[0123] Lpc=(s1-1)×d0×N a

[0124]

[0125] Where s1 is the ratio of the lateral spacing of the fine flow tubes to the outer diameter of the fine flow tubes of the precooler;

[0126] At the same time, calculate the heat transfer area A h :

[0127] A h =πd0×Lfc×N t_all

[0128] Step 3: Simplify the heat transfer limit T of the precooler model according to the engine design point limit Calculate the total temperature T of the cold flow outlet of the precooler out,c , total temperature of cold flow inlet of precooler T in,c and the total pressure of the cold flow inlet of the precooler P in,c Transfer parameters calculated for closed helium cycle compressor components; by energy conservation, Q in =Q out , the heat absorption and heat release are equal, combined with the physical properties of air and helium, the mass flow rate W of the cold flow inlet of the precooler is obtained in,c :

[0129]

[0130] Where C p_air and C p_He are the specific heats of air and helium at constant pressure, respectively;

[0131] Then calculate the qualitative temperature T of the high temperature side of the precooler according to the inlet and outlet temperatures of the high and low temperature sides h,average , qualitative temperature T on the low temperature side of the precooler c,average :

[0132]

[0133] The high temperature side temperature T h,average and the total inlet pressure P in,h The physical parameters of the high-temperature side fluid air, dynamic viscosity μ, are calculated by interpolation from the database published by NIST. h , thermal conductivity λ h and the Prandtl number Pr h ;

[0134] The Reynolds number of the high temperature side fluid is calculated using the Reynolds number calculation formula. h :

[0135]

[0136] Where ρ, v, and d represent the fluid density, flow velocity, and flow channel diameter, respectively, and μ represents the dynamic viscosity of the fluid;

[0137] The low temperature side qualitative temperature T c,average and the total inlet pressure P in,c The physical parameters of the low-temperature side fluid helium, dynamic viscosity μ, are calculated by interpolation from the database published by NIST. c , thermal conductivity λ c and the Prandtl number Prc ;

[0138] The Reynolds number of the low temperature side fluid is calculated using the Reynolds number calculation formula. c :

[0139]

[0140] Given the initial value of the ratio of the cold flow gas thermal resistance to the total thermal resistance, the wall temperature T w for:

[0141]

[0142] Where Rc is the cold flow thermal resistance, R is the total thermal resistance;

[0143] Through the wall temperature T w and the total inlet pressure P in,h The wall fluid Prandtl number Pr is calculated by interpolation from the database published by NIST w For the high-temperature side fluid, the Nusselt number Nu of the high-temperature side fluid is obtained using the Zhukauskas cross-cross tube number correlation formula h :

[0144]

[0145] At this time, calculate the convection heat transfer coefficient h of the high temperature side fluid h With Stanton Number St h :

[0146]

[0147] For the low-temperature fluid side, the Nusselt number Nu of the low-temperature side fluid is obtained using the Gnielinski formula for turbulent forced convection heat transfer in the tube groove. c :

[0148]

[0149] Where f is the Darcy drag coefficient of turbulent flow in the tube, according to the Filonenko formula:

[0150] f=(1.82×lgRe c -1.64) -2

[0151] For gas:

[0152]

[0153] Among them, c t Indicates the temperature difference correction coefficient, T c Indicates the average temperature of the fluid on the low temperature side;

[0154] At this time, calculate the convective heat transfer coefficient h of the low temperature side fluid c With Stanton Number St c ;

[0155] Then calculate the cold flow thermal resistance R c 、Heat flow thermal resistance R h , pipe wall thermal resistance R w , total thermal resistance R and total heat transfer coefficient k of the precooler:

[0156]

[0157] Then, substitute the obtained parameters into the wall temperature calculation again and repeat step 3 to correct the qualitative parameters;

[0158] Step 4: Use the heat transfer unit number method to calibrate the precooler based on the heat transfer value Φ1 and calculate the actual outlet temperature:

[0159] φ1=(q m c) min (T in -T out ) max =η(q m c) min (T in,h -T in,c )

[0160] Where (q m c) min is the value on the side with smaller heat capacity flow rate, (T in -T out ) max is the maximum temperature difference that may occur in the precooler, η is the precooler efficiency; T in 、T out represent the fluid inlet temperature and outlet temperature respectively;

[0161] The heat transfer coefficient k and heat transfer area A obtained above h And the temperature drop Δt given by the design point, we can get contrast Is it equal to Qin in step 3? If not, repeat steps 2 to 4 using the pipe length Lfc as the variable, perform iterative solution, and calculate the actual outlet temperature. At the same time, correct the pipe length Lfc calculated during the design to give the final pipe length.

[0162] Step 4: Use the heat transfer unit number method to calibrate the precooler based on the heat transfer value Φ1 and calculate the actual outlet temperature:

[0163] φ1=(q m c) min (Tin -T out ) max =ε(q m c) min (T in,h -T in,c )

[0164] Where (q m c) min is the value on the side with smaller heat capacity flow rate, (T in -T out ) max is the maximum temperature difference that may occur in the precooler, and ε is the precooler efficiency.

[0165] At this time, repeat the operation of step 2 to recalculate the corrected tube length Lfc and the volume V of a single microtube. t_single With mass m t_single , total mass of precooler m all , the total volume of the precooler tube V t_all , total volume of precooler V all , we can also calculate the heat transfer area A outside the tube h_out 、Heat exchange area in the tube A h_in And the precooler heat exchange effectiveness ε.

[0166] Step 5: Use the SEHaaland formula to calculate the friction loss f in the tube. c calculate:

[0167]

[0168] Where k d is the roughness inside the tube;

[0169] The dynamic pressure loss caused by the flow in the precooler tube is:

[0170]

[0171] Where, v c represents the flow rate of the fluid on the low temperature side, ρ c represents the density of the fluid on the low temperature side;

[0172] For the flow resistance calculation of the high-temperature side fluid, the friction loss fh in the tube is calculated:

[0173]

[0174] The dynamic pressure loss caused by the high-temperature fluid flow outside the precooler tube is:

[0175]

[0176] Where, ρh represents the density of the fluid on the high temperature side, v h Indicates the fluid flow rate on the high-temperature side;

[0177] At this time, the total pressure P at the hot flow outlet of the precooler is calculated out,h , total pressure of cold stream outlet P out,c And the total pressure on the high temperature side of the precooler is restored Σ h , low temperature side total pressure recovery Σ c ;

[0178] P out,h =P in,h -P lost,h ;P out,c =P in,c -P lost,c

[0179]

[0180] At this point, the performance parameters and structural parameters of the inlet and outlet of the high and low temperature sides of the precooler have been obtained, and the calculation is completed.

[0181] Example:

[0182] A rapid calculation and evaluation method for the performance of a cryogenic combined cycle engine precooler includes the following calculation steps:

[0183] (1) This specific implementation scheme takes the calculation of the design point of a cryogenic combined cycle engine as an example. Before calculating the performance parameters of the entire engine, it is necessary to first calculate the outlet parameters of the high-temperature side and low-temperature side of the precooler, as well as the performance parameters of the heat exchanger.

[0184] (2) Input the atmospheric conditions of the engine: altitude 25.7km, Mach number Ma5, and calculate the total temperature of the air before entering the precooler T 12 =1253.62K, total pressure P 12 =185.7kPa, air flow rate into the precooler W a =100.0kg / s, according to the cooling temperature requirement Δt of the high-temperature fluid in the precooler, the high-temperature side precooler outlet temperature T is obtained. 12 =158.62K.

[0185] (3) Before calculating the performance of the precooler components, it is also necessary to calculate the helium flow path and the starting temperature of the helium cycle T 21 =55K, initial pressure P 21 =5.6MPa, helium compressor pressure ratio PR He =3.4, helium compressor efficiency ETA He =0.82, and using the law of conservation of energy, we can calculate: the total temperature of the helium inlet of the precooler T 22 =101.1K, total pressure P22 =20.5MPa, outlet total temperature T 23 =950K, helium flow rate W He =26.8kg / s.

[0186] (4) Input precooler design parameters, microtube inner diameter d i =0.90mm, outer diameter d o =0.98mm, transverse spacing to diameter ratio s1 = 1.8, longitudinal spacing to diameter ratio s2 = 1.5, precooler inner diameter r i =0.53m, the central angle of the helium fine flow tube of a single module of the precooler β = 180°, the number of precooler manifold modules N m =140, number of tube rows in a single module N t =1, number of axial tubes N a =1000, preliminary calculations yield:

[0187] The length of a single fine tube of the precooler lfc = 1.8600m, the total heat transfer area A h =801.7149m 2 .

[0188] (5) Calculate the qualitative temperature and total inlet pressure from the inlet and outlet temperatures of the air side and the helium side, and use the NIST database to interpolate and cyclically correct the calculated fluid physical parameters to obtain:

[0189] High temperature side Reynolds number Re h =993.6, Nusselt number Nu h =22.3, convective heat transfer coefficient h h =1186.4W / (m 2 K), high temperature side thermal resistance R h =8.42e -4 K / W, thermal resistance R on the tube wall w =2.08e -6 K / W.

[0190] Low temperature side Reynolds number Re c =9120.7, Nusselt number Nu c =27.6, convective heat transfer coefficient h c =7332.9W / (m 2 K), thermal resistance R c =1.48e -4 K / W. Precooler total convection heat transfer coefficient h=1006.6W / (m 2 ·K).

[0191] (6) Use the ε-NTU method to check the outlet temperature. Is the calculated outlet temperature close to the outlet temperature in step (2)? If not, continue iterating the pipe length lfc until the outlet temperature is close. After correction, the pipe length lfc = 1.8611 m.

[0192] (7) The flow resistance is calculated and the high temperature side fluid dynamic pressure loss p is obtained. h,lost =42.145kPa, low temperature side fluid dynamic pressure loss p c,lost =687.585kPa, total pressure recovery coefficient of precooler high temperature side Σ h =0.7729, total pressure recovery coefficient Σ on the low temperature side c =0.9665.

[0193] (8) Recalculate the precooler performance parameters and size and weight parameters:

[0194] Precooler tube weight m h =253.46kg, precooler axial length lpc = 1.764m, precooler volume 0.674m 3 The heat exchanger is compact at 1189.2m 2 / m 3 , heat transfer effectiveness ε=0.9516, heat transfer capacity q=118.3MW.

[0195] Calculation completed.

Claims

1. A rapid evaluation and calculation method for the performance of a cryogenic combined cycle engine precooler, characterized in that: The steps include: Step 1: Given the engine operating altitude H, Mach number Ma and engine mass flow rate W a , the total temperature T at the inlet of the air path precooler is obtained by the variable specific heat calculation method in,h , Total pressure P at the inlet of air flow path precooler in,h ; The air flow path precooler inlet mass flow W is calculated based on the flow ratio entering the core flow path in,h According to the required temperature drop of the engine cooling high temperature incoming air, the total temperature T of the precooler air flow outlet is obtained out,h According to the law of flow conservation, the mass flow rate W of the precooler air flow outlet is obtained out,h ; Step 2: Use the precooler geometric design parameters given by the design point: precooler inner diameter r i , the central angle β0 of the helium fine flow tube of a single module of the precooler, and the length Lfc of a single fine flow tube of the precooler are calculated using the Archimedean spiral arc length formula; the equation of the Archimedean spiral in polar coordinates is expressed as: r=a+bβ,0≤β≤β0 a=r i ,b=sa / 2π s a =s2×d0×N tm ×N t Where a is the polar diameter, β is the polar angle, r is the precooler radius, s a is the pitch between modules, d0 is the outer diameter of the precooler fine flow tube, s2*d0 is the longitudinal spacing of the fine flow tube, N tm is the number of precooler modules, N t is the number of tube rows in a single module of the precooler, β0 is the central angle of the fine flow tube, s2 is the ratio of the longitudinal spacing of the fine flow tube to the outer diameter of the fine flow tube of the precooler; The differential expression of pipe length is: Integrate to get the length of the micro flow tube: Precooler outer diameter: r o ＝r i +s a / 2π×β0 Then, according to the inner diameter d of the microtube i , outer diameter d0, tube length Lfc and material density ρ tube Calculate the volume V of a single microtubule t_single With mass m t_single , and then according to the number of precooler modules N tm 、Number of tube rows in a single module of precooler t And the number of axial tubes N a Calculate the total number of microtubules N t_all , total mass of precooler m all , the total volume of the precooler tube V t_all , total volume of precooler V all And the total length of the precooler, that is, the axial length Lpc: m t_single =ρ tube V t_single N t_all =N tm ×N t ×N a m all =N t_all ×m t_single V t_all =V t_single ×N t_all Lpc=(s1-1)×d0×N a Where s1 is the ratio of the lateral spacing of the fine flow tubes to the outer diameter of the precooler fine flow tubes; At the same time, calculate the heat transfer area A h : A h =πd0×Lfc×N t_all Step 3: Simplify the precooler model heat transfer limit T according to the engine design point limit Calculate the total temperature T of the cold flow outlet of the precooler out,c , total temperature of cold flow inlet of precooler T in,c and the total pressure of the cold flow inlet of the precooler P in,c Transfer parameters calculated for closed helium cycle compressor components; by energy conservation, Q in =Q out , the heat absorption and heat release are equal, combined with the physical properties of air and helium, the mass flow rate W of the cold flow inlet of the precooler is obtained in,c : Where C p_air and C p_He are the specific heats of air and helium at constant pressure, respectively; Then calculate the qualitative temperature T of the high temperature side of the precooler according to the inlet and outlet temperatures of the high and low temperature sides h,average , qualitative temperature T on the low temperature side of the precooler c,average : The high temperature side temperature T h,average and the total inlet pressure P in,h The physical parameters of the high-temperature side fluid air, dynamic viscosity μ, are calculated by interpolation from the database published by NIST. h , thermal conductivity λ h and the Prandtl number Pr h ; The Reynolds number of the high temperature side fluid is calculated using the Reynolds number calculation formula. h : Where ρ, v, and d represent the fluid density, flow velocity, and flow channel diameter, respectively, and μ represents the dynamic viscosity of the fluid; The low temperature side qualitative temperature T c,average and the total inlet pressure P in,c The physical parameters of the low-temperature side fluid helium, dynamic viscosity μ, are calculated by interpolation from the database published by NIST. c , thermal conductivity λ c and the Prandtl number Pr c ; The Reynolds number of the low temperature side fluid is calculated using the Reynolds number calculation formula. c : Given the initial value of the ratio of the cold flow gas thermal resistance to the total thermal resistance, the wall temperature T w for: Where Rc is the cold flow thermal resistance, R is the total thermal resistance; Through the wall temperature T w and the total inlet pressure P in,h The wall fluid Prandtl number Pr is calculated by interpolation from the database published by NIST w For the high-temperature side fluid, the Nusselt number Nu of the high-temperature side fluid is obtained using the Zhukauskas cross-cross tube number correlation formula h : At this time, calculate the convection heat transfer coefficient h of the high temperature side fluid h With Stanton Number St h : For the low-temperature fluid side, the Nusselt number Nu of the low-temperature side fluid is obtained using the Gnielinski formula for turbulent forced convection heat transfer in the tube groove. c : Where f is the Darcy drag coefficient of turbulent flow in the tube, according to the Filonenko formula: f=(1.82×lgRe c -1.64) -2 For gas: Among them, c t Indicates the temperature difference correction coefficient, T c Indicates the average temperature of the fluid on the low temperature side; At this time, calculate the convective heat transfer coefficient h of the low temperature side fluid c With Stanton Number St c ; Then calculate the cold flow thermal resistance R c 、Heat flow thermal resistance R h , pipe wall thermal resistance R w , total thermal resistance R and total heat transfer coefficient k of the precooler: Then, substitute the obtained parameters into the wall temperature calculation again and repeat step 3 to correct the qualitative parameters; Step 4: Use the heat transfer unit number method to calibrate the precooler based on the heat transfer value Φ1 and calculate the actual outlet temperature: φ1=(q m c) min (T in -T out ) max =η(q m c) min (T in,h -T in,c ) Where (q m c) min is the value on the side with smaller heat capacity flow rate, (T in -T out ) max is the maximum temperature difference that may occur in the precooler, η is the precooler efficiency; T in 、T out represent the fluid inlet temperature and outlet temperature respectively; The heat transfer coefficient k and heat transfer area A obtained above h And the temperature drop Δt given at the design point, calculate φ = kAΔt, and compare whether φ is equal to Qin in step 3. If not, use the pipe length Lfc as the variable and repeat steps 2 to 4 for iterative solution to find the actual outlet temperature. At the same time, correct the pipe length Lfc calculated during design to give the final pipe length. Repeat step 2 to recalculate the corrected tube length Lfc and the volume V of a single microtubule. t_single With mass m t_single , total mass of precooler m all , the total volume of the precooler tube V t_all , total volume of precooler V all , and calculate the heat transfer area A outside the tube h_out 、Heat exchange area in the tube A h_in and the heat exchange effectiveness of the precooler ε; Step 5: Use the SE Haaland formula to calculate the friction loss fc inside the tube: Where k d is the roughness inside the tube; The dynamic pressure loss caused by the flow in the precooler tube is: Where, v c represents the flow rate of the fluid on the low temperature side, ρ c represents the density of the fluid on the low temperature side; For the flow resistance calculation of the high-temperature side fluid, the friction loss fh in the tube is calculated: The dynamic pressure loss caused by the high-temperature fluid flow outside the precooler tube is: Where, ρ h represents the density of the fluid on the high temperature side, v h Indicates the fluid flow rate on the high-temperature side; At this time, the total pressure P at the hot flow outlet of the precooler is calculated out,h , total pressure of cold stream outlet P out,c And the total pressure on the high temperature side of the precooler is restored Σ h , low temperature side total pressure recovery Σ c ; P out,h =P in,h -P lost,h ;P out,c =P in,c -P lost,c At this point, the performance parameters and structural parameters of the inlet and outlet of the high and low temperature sides of the precooler have been obtained, and the calculation is completed.

2. A rapid evaluation and calculation method for the performance of a cryogenic combined cycle engine precooler according to claim 1, characterized in that: The cold flow gas is helium.

3. A computer program, characterized in that The computer program enables a computer to execute the method according to any one of claims 1 to 2.

4. An electronic device, characterized in that: include: processor and memory; The memory is used to store a computer program, and the processor is used to execute the computer program stored in the memory, so that the electronic device performs the method according to any one of claims 1 to 2.

5. A computer-readable storage medium having a computer program stored thereon, characterized in that: When the computer program is executed by a processor, the method according to any one of claims 1 to 2 is implemented.

6. A chip, characterized in that: include: A processor, configured to call and run a computer program from a memory, so that a device equipped with the chip executes the method according to any one of claims 1 to 2.

7. A computer program product, characterized in that The computer program product comprises a computer storage medium storing a computer program, wherein the computer program comprises instructions executable by at least one processor, and when the instructions are executed by the at least one processor, the method according to any one of claims 1 to 2 is implemented.

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