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An active system for controlling the wing flap flow on a model of a passenger aircraft wing section

https://doi.org/10.38013/2542-0542-2020-4-41-46

Abstract

In this work, a model of an active system for controlling the wing flap flow was designed and manufactured. The presented active flow control system operates by blowing air under pressure onto the upper surface of the flap. The system consists of a device supplying compressed air to the flap and the flap leading edge, through which the air is blown out. For experimental testing, the system was built into the existing large-scale aerodynamic model of a mechanized wing compartment.

For citation:


Zhogolev D.A., Kopylov A.A., Nikulenko A.A., Sevostyanov S.Ya., Sudakov V.G. An active system for controlling the wing flap flow on a model of a passenger aircraft wing section. Journal of «Almaz – Antey» Air and Space Defence Corporation. 2020;(4):41-46. https://doi.org/10.38013/2542-0542-2020-4-41-46

Introduction

The application of active systems for controlling the airflow around airfoils of wing high-lift devices is one of the most prevailing trends for improving the performance of aircraft under development [1]. With multiple results and theoretical calculation studies available, their experimental verification is scarce. Problem-oriented calculations and limited experimental studies have been carried out for substantially simplified configurations of streamlined surfaces (cylinders with outblowing slots open to the boundary layer, rectangular surfaces with simulated airfoil tailoring). This work is intended to solve the problem related to the study of boundary layer control efficiency by means of controlled jet blowing for typical aerodynamic configuration of a mainline aircraft. It is definitely urgent to estimate the efficiency of boundary layer control for the movable flap with regard to the estimation of a probable increase in the lift force of the “wing-movable flap” system in takeoff and landing conditions.

This paper describes the development of an aerodynamic model of the mechanized wing section and the implementation of a system for jet blowing in the boundary layer in order to study its active control at takeoff and landing of a mainline aircraft.

The most reasonable solution is to study such systems using large-scale aerodynamic models that allow to approximate to real aircraft flight conditions and, therefore, actualize the experimental studies [2].

For research purposes, we made a decision to use a prefabricated large-sized aerodynamic model of the mechanized wing section. The flow control system has been developed regarding its application in the existing model. The aerodynamic model is a mechanized wing section, the dimensions of which are as near as possible to real aircraft dimensions (scale ~ 1:1). In terms of design, the model comprises a wing section, a leading edge slat, a plane flap, shut-off washers and an engine nacelle. Model dimensions: length 7900 mm, width 6000 mm. Model weight: 5200 kg.

Design of active wing flap flow control system

The system comprises a device supplying compressed air to the flap and to the leading edge of the flap. Then the air under pressure is blown out through shaped slots and holes of the leading edge onto the upper surface of the flap.

The device supplying compressed air to the flap is a branched air line consisting of rigid steel and aluminium pipes, flexible steel braided pipes and flexible corrugated pipes made of stainless steel (Fig. 1). One section of the air line supplying compressed air is arranged outside the model and is connected to the other section. The other section of the air line passes through the nose of the wing section, then goes inside the wing section passing through its front wall, approximately through its centre. Both sections of the air line are made of rigid steel pipes of a large diameter (~ ∅100 mm). Further, the air line located inside the wing section is divided into three branch lines connected to the rear wall of the section. The air line consists of flexible steel braided pipes and rigid pipes made of aluminium alloy. The diameter of these pipes is smaller than the diameter of the air supply line pipes. Each pipe located in the rear wall area is connected to corrugated steel pipes. Further, corrugated steel pipes are laid inside the trailing edge of the model and are connected directly to the flap.


Fig. 1
. Arrangement of active airflow control system elements on the model

The pipe types are selected based on the following:

  • pipe operating conditions under high air pressure with them retaining tightness at connecting joints;
  • pipes shall be installed within the outlines of the prefabricated model with regard to the existing structural elements;
  • pipe cross-section areas shall remain proportional to those of the slots on the flap leading edge, thorough which air is blown out onto the upper surface of the flap. Proportionality of the pipe cross-section areas ensures uniform air outblow onto the upper surface of the flap within its entire span.

With a variety of available commercial pipe products, the most preferable choice is to use flexible corrugated stainless steel pipes to be installed in the area of the wing section’s trailing edge. This choice is due to the requirements for pipes featuring numerous elbows in order to install them between closely-spaced structural elements of the model. Using flexible corrugated pipes together with swivel connections (Fig. 2) arranged on the leading edge of the flap allowed to turn the flap through an angle of up to 60 degrees. When the flap turns, corrugated pipes are bent with their cross-section areas unchanged while pipes can withstand high air pressure; when turning, air supply swivel connections prevent intolerable bending and fractures in corrugated pipes in the area where they are connected to the flap.


Fig. 2
. Air supply swivel connections on the leading edge of the flap

The leading edge of the flap comprises four removable nose sections. Each nose section has inner airtight cavities, which receive air under the pressure of 4 atm from the device supplying compressed air to the flap. The air is blown out under pressure onto the upper surface of the flap. Two methods to blow the air out of the flap have been implemented: tangential blowing (Fig. 3) and air blowing with formation of air jet vortex generators (Fig. 4).


Fig. 3
. Tangential blowing

Fig. 4
. Air blowing with formation of air jet vortex generators

Special-purpose inserts in the flap nose sections provide for the two different types of blowing. Some inserts have rectangular slots, while the other ones have holes arranged at two different angles relative to the normal of the surface being blown. Airtight cavities inside removable nose sections are intended to obtain uniform air blowing from the shaped slots or holes.

During experiment, the airflow is visualized using small turfs that fully fit against the flap surface under the attached airflow and move in case of the detached airflow. To record the airflow behaviour, the model has a special box with a video camera and lighting fixtures installed in the dedicated location (Fig. 5).


Fig. 5
. Box with windows for video camera lighting fixtures installed inside

Conclusion

As a result of the work, we have developed the flap airflow control system and manufactured its prototype model. Besides, we have carried out experimental studies using the T-101 wind tunnel at TsAGI.

Due to the development of the airflow control system, we have carried out an aerodynamic experiment using the wind tunnel, but without real aircraft flight tests, because it involves heavy costs to prepare and conduct such an experiment in real flight conditions. It is expensive to develop an airborne system of the kind since it requires considerable modernization of the engine systems along with implementation of an auxiliary air system inside the wind structure. Such modifications are difficult to implement in the design of the existing aircraft.

References

1. Разработка принципиальной конструктивной схемы и технологии большеразмерной аэродинамической модели крыла (в аэродинамическую установку Т-101). Научно-технический отчет № 10/3092, ЦАГИ, 2000 г.

2. Петров А.В. Аэродинамика транспортных самолетов короткого взлета и посадки с энергетическими системами увеличения подъемной силы. М.: Инновационное машиностроение, 2018.


About the Authors

D. A. Zhogolev
Central Aerohydrodynamic Institute (TsAGI)
Russian Federation

Zhogolev Denis Alekseevich - Engineer of the 2nd category, Research interests: aerodynamic models.

Zhukovsky, Moscow region


A. A. Kopylov
Central Aerohydrodynamic Institute (TsAGI)
Russian Federation

Kopylov Kopylov Aleksey Anatolevich - Sectoral Head, Research interests: aerodynamic models.

Zhukovsky, Moscow region


A. A. Nikulenko
Central Aerohydrodynamic Institute (TsAGI)
Russian Federation

Nikulenko Aleksey Alekseevich - Leading Design Engineer, Research interests: aerodynamic models.

Zhukovsky, Moscow region


S. Ya. Sevostyanov
Central Aerohydrodynamic Institute (TsAGI)
Russian Federation

Sevostyanov Sergey Yakovlevich - Leading Design Engineer, Research interests: development of aerodynamic models and hydraulic systems.

Zhukovsky, Moscow region


V. G. Sudakov
Central Aerohydrodynamic Institute (TsAGI)
Russian Federation

Sudakov Vitaly Georgievich - Dr. Sci. (Phys.- Math.), Assoc. Prof., Deputy Head, Research interests: aerodynamics, mechanics of liquids and gases.

Zhukovsky, Moscow region


For citation:


Zhogolev D.A., Kopylov A.A., Nikulenko A.A., Sevostyanov S.Ya., Sudakov V.G. An active system for controlling the wing flap flow on a model of a passenger aircraft wing section. Journal of «Almaz – Antey» Air and Space Defence Corporation. 2020;(4):41-46. https://doi.org/10.38013/2542-0542-2020-4-41-46

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ISSN 2542-0542 (Print)