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Online prediction method for stagnation point heat flow in flight process of aircraft

A flight process and aircraft technology, applied in the direction of instruments, electrical digital data processing, computer-aided design, etc., can solve problems such as limited heat flow function forms, and achieve the effect of accurate heat flow prediction

Active Publication Date: 2021-07-02
ZHEJIANG UNIV
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Problems solved by technology

Cui Miao uses the dimensionless objective equation to identify the parameters of the heat flow model, but it is limited to the known heat flow function form

Method used

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  • Online prediction method for stagnation point heat flow in flight process of aircraft
  • Online prediction method for stagnation point heat flow in flight process of aircraft
  • Online prediction method for stagnation point heat flow in flight process of aircraft

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Embodiment Construction

[0024] The present invention will be further elaborated below.

[0025] Firstly, the hypersonic hemispherical head flows around, under the dissociated gas thermal equilibrium flow, the zero angle of attack stagnation point steady continuous laminar flow, the engineering estimation formula of the steady state heat transfer heat flow rate:

[0026]

[0027] where q s is the heat flow rate at the stagnation point; ρ ∞ is the flow density; R N is the radius of curvature of the spherical head; hw is the wall enthalpy; stagnation enthalpy hs is,

[0028]

[0029] where V ∞ is the flow velocity; T ∞ is the flow temperature.

[0030] According to this formula, and considering the flight conditions given in this topic, the heat flow formula is simplified to the following form:

[0031]

[0032] Among them, A, B, C, and D are coefficients to be fitted, and logarithms are taken on both sides:

[0033] lnq s =-0.5 lnR N +lnA+B·lnρ ∞ +C lnV ∞ +D·ln(T W -T ∞ ) (4)

[...

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Abstract

The invention discloses an online prediction method for stagnation point heat flow in the flight process of an aircraft. The method comprises the following steps: 1) before actual flight, carrying out one-dimensional heat flow identification through a sequence function method by utilizing temperature data of each measuring point in a structure, and training a neural network three-dimensional correction model in combination with actually measured heat flow; 2) simplifying the Fay-Riddell stationary point heat flow engineering estimation formula, taking the actually measured heat flow and the incoming flow condition of a given trajectory as an input sequence, and correcting various coefficients in the simplified formula through a least square method to obtain a preliminary stationary point heat flow prediction formula; and 3) during actual flight, taking the stationary point identification heat flow updated in real time as new heat flow data, and performing real-time fitting through a least square method to obtain a prediction formula updated in real time to predict a stationary point heat flow value in future 10 seconds. The heat flow error indicated by the method is within 15%, and the invention comprises the rapidity of engineering estimation, so that real-time and accurate heat flow indication in the flight process can be realized.

Description

technical field [0001] The invention relates to an online prediction method of stagnation point heat flow during the flight of an aircraft, which is suitable for predicting the stagnation point heat flow during the actual flight of the aircraft. Background technique [0002] Hypersonic flight faces serious aerodynamic heating problems. Due to the strong friction and compression of the air, a large amount of kinetic energy is converted into heat energy, causing the air temperature around the aircraft to rise sharply. The high temperature affects the structural strength and rigidity of the aircraft, and even causes ablation damage to the outer surface. The design of thermal protection system is an important support for the rapid development of hypersonic flight technology, and its research design requires a large amount of test data from flight tests. The measurement of key parameters such as temperature and heat flow during aircraft service is a necessary means to evaluate t...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): G06F30/27G06F30/28G06F113/08G06F119/08
CPCG06F30/27G06F30/28G06F2113/08G06F2119/08Y02T90/00
Inventor 陈伟芳沈煊赵文文江中正
Owner ZHEJIANG UNIV
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