One-dimensional evaluation method of combustion efficiency for scramjet engine
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An evaluation method and combustion efficiency technology, applied in the field of one-dimensional evaluation of the combustion efficiency of the scramjet combustion chamber, can solve the problem of ignoring the influence of fuel injection momentum and energy changes, ignoring wall friction and endothermic effect, and limiting the general method. adaptability and other issues to achieve the effect of broadening the scope of application
Inactive Publication Date: 2009-09-23
HARBIN INST OF TECH
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In engineering, one-dimensional methods often ignore some existing factors, which limits the universality of the method to a certain extent
To sum up, there are the following limiting assumptions in the previous
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specific Embodiment approach 1
[0045] Specific implementation mode one: as figure 1 As shown, the one-dimensional evaluation method of the combustion efficiency of the scramjet described in this embodiment is realized according to the following steps:
[0046] Step 1. Determine the inlet conditions and pressure distribution of the combustion chamber: Obtain the pressure distribution of the scramjet combustion chamber wall through experiments or numerical simulations, and establish the molecular weight and enthalpy database of each component in the combustion chamber according to the physical property analysis software (such as ASPEN) , establish the functional relationship μ(p, T, α) and H(p, T, α) of molecular weight and enthalpy with pressure, temperature and mixture composition; given the total mass flow rate and the fraction of each component at the entrance of the combustion chamber, determine G τ , G o , L oτ ,α,H BX * and I BX , using the mutual transformation between the combustion efficiency ...
specific Embodiment approach 2
[0082] Specific implementation mode two: In step six in this embodiment mode, the equilibrium dissociated gas method is used for calculating the local sound velocity and Mach number of the combustion chamber section:
[0083] h kc =g τkc h τ (p τkc ,T kc ,α=0)+g okc h o (p okc ,T kc ,α=∞)+g nckc h nc (p nckc ,T kc ,α=1) (10)
[0084] c p = ( ∂ H kc ∂ T kc ) p kc - - - ( 11 )
[0085] c v = c p - R ...
specific Embodiment approach 3
[0090] Specific implementation mode three: In step seven of this implementation mode, the friction loss on the wall surface of the combustion chamber adopts the semi-empirical formula of the flat plate non-gradient turbulent boundary layer:
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Abstract
A one-dimensional evaluation method of combustion efficiency for scramjet engine relate to an evaluation method of combustion efficiency for engine. The method realizes quick evaluation for economic performance in combustion condition; and the application range of the existing one-dimensional evaluation method is enlarged so as to have universality. The method has the following steps: the entry condition and pressure distribution are ensured; the initial value eta0 of combustion efficiency is given; each component mass fraction g at the section of combustion chamber is ensured; the combustion mixture temperature Tkc is ensured; the combustion mixture enthalpy value Hkc and average molecular weight mukc are calculated; the local sound velocity a and mach number M at the section of combustion chamber are calculated; the friction coefficient cf at the wall surface of combustion chamber and the dissipative force X0 along flow direction are ensured; the combustion mixture flow speed velocity w, the heat current qw at the wall surface of combustion chamber and the calculated value eta of combustion efficiency are calculated; and whether the combustion efficiency is the same as the initial value is judged. The application of the method can quickly analyze ultrasonic speed combustion efficiency and related thermal and pneumatic parameters, and finally obtains one-dimensional distribution rule of combustion efficiency and related parameters along axial direction of combustion chamber.
Description
technical field [0001] The invention relates to a method for evaluating the combustion efficiency of an engine, in particular to a one-dimensional evaluation method for the combustion efficiency of a combustion chamber of a scramjet engine. Background technique [0002] At present, the three research and development methods of scramjet are ground test, flight test and numerical simulation. The ground test is the most basic method, which must have the ability to simulate the downflow components, total pressure, total temperature and velocity under actual flight conditions, and has high requirements for experimental equipment, simulation methods, measurement techniques, data processing, etc.; the cost of flight tests is huge, requiring A complete ground support system is used as the final verification method; numerical simulation provides detailed flow characteristics of the entire flow field, but the computer time is long, and calculation convergence depends on calculation co...
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