Gas actuator dynamics model and its equivocations

Аuthors

Yanyshev D. S.^*, Bykov L. V.^**

Moscow Aviation Institute (National Research University), 4, Volokolamskoe shosse, Moscow, А-80, GSP-3, 125993, Russia

*e-mail: dyanishev@gmail.com
**e-mail: bykovlv@mai.ru

Abstract

Gas actuators play a great role in modern aircraft building. However, a lot of difficulties occur while designing actuators with short operating time. The lack of adequate mathematical models results in the higher costs of experimental researches needed to optimize design.

A model of gas actuator dynamic, generated by considering gas mass and energy balance in actuator cavities is presented in the paper. The balance equations are derived by integrating general continuity and energy equations over the volumes of actuator cavities and by using Gauss divergence theorem.

The main equivocations of the model, which occur in actuators with short operating time periods, are revealed. The methods for eliminating these equivocations are given. The modeling results obtained, using adjusted model, are stated.

In this paper it is shown that in case of short operating time actuator a zero-dimensional model of a gas actuator yields to substantial errors. These errors could be corrected by 3D modeling and by using the experimental data.

The non-uniform pressure field inside the actuator is the main factor that influences onto actuators dynamic. The second factor is the velocity profile. And the third important factor is a width of technological gaps in an actuator since these gaps define mass flow rate being exhausted from the actuator.

Authors reveal that the first and the third factors are of utter importance, while the second one could be sometimes neglected at all.

In this paper authors use two extra coefficients derived from the results of CFD-modeling and test data to adjust the mathematical model of the actuator.

The model after modernisation could be used for design optimization of the actuator.

Keywords:

mathematical modeling, gas actuators, gas dynamic, jet streams, balance equations, unsteady processes

References

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