Purpose

This paper aims to achieve an optimum flow separation control over the airfoil using a passive flow control method by introducing a bio-inspired nose near the leading edge of the National Advisory Committee for Aeronautics (NACA) 4 and 6 series airfoil. In addition, to find the optimised leading edge nose design for NACA 4 and 6 series airfoils for flow separation control.

Design/methodology/approach

Different bio-inspired noses that are inspired by the cetacean species have been analysed for different NACA 4 and 6 series airfoils. Bio-inspired nose with different nose length, nose depth and nose circle diameter have been analysed on airfoils with different thicknesses, camber and camber locations to understand the aerodynamic flow properties such as vortex formation, flow separation, aerodynamic efficiency and moment.

Findings

The porpoise nose design that has a leading edge with depth = 2.25% of chord, length = 0.75% of chord and nose diameter = 2% of chord, delays the flow separation and improves the aerodynamic efficiency. Average increments of 5.5% to 6° in the lift values and decrements in parasitic drag (without affecting the pitching moment) for all the NACA 4 and 6 series airfoils were observed irrespective of airfoil geometry such as different thicknesses, camber and camber location.

Research limitations/implications

The two-dimensional computational analysis is done for different NACA 4 and 6 series airfoils at low subsonic speed.

Practical implications

This design improves aerodynamic performance and increases the structural strength of the aircraft wing compared to other conventional high lift devices and flow control devices. This universal leading edge flow control device can be adapted to aircraft wings incorporated with any NACA 4 and 6 series airfoil.

Social implications

The results would be of significant interest in the fields of aircraft design and wind turbine design, lowering the cost of energy and air travel for social benefits.

Originality/value

Different bio-inspired nose designs that are inspired by the cetacean species have been analysed for NACA 4 and 6 series airfoils and universal optimum nose design (porpoise airfoil) is found for NACA 4 and 6 series airfoils.

中文翻译：

---

使用生物启发式机头进行流分离控制，适用于NACA 4和6系列机翼

目的

本文旨在通过在美国国家航空航天咨询委员会（NACA）4和6系列机翼的前沿附近引入生物启发式机头，从而采用被动式流量控制方法来实现对机翼的最佳流分离控制。此外，要找到用于流分离控制的NACA 4和6系列机翼的优化前缘设计。

设计/方法/方法

分析了鲸类物种激发的不同生物激发的鼻子，以分析不同的NACA 4和6系列机翼。在具有不同厚度，外倾角和外倾角位置的翼型上分析了具有不同鼻子长度，鼻子深度和鼻圈直径的受生物启发的鼻子，以了解空气动力流动特性，例如涡流形成，流动分离，空气动力效率和力矩。

发现

海豚鼻子设计的前缘深度=弦的2.25％，长度=弦的0.75％，鼻直径=弦的2％，延迟了气流分离并提高了空气动力学效率。观察到所有NACA 4和6系列翼型的升力值平均增加5.5％至6°，并且寄生阻力减小（不影响俯仰力矩），而与翼型几何形状（例如厚度，外倾角和外倾角位置）无关。

研究局限/意义

在低亚音速下对不同的NACA 4和6系列机翼进行了二维计算分析。

实际影响

与其他传统的高升力设备和流量控制设备相比，该设计提高了空气动力学性能并提高了飞机机翼的结构强度。这种通用的前缘流控制装置可适用于装有任何NACA 4和6系列机翼的飞机机翼。

社会影响

该结果将在飞机设计和风力涡轮机设计领域引起巨大兴趣，从而降低能源和航空旅行的成本，从而带来社会效益。

创意/价值

已经分析了鲸类物种激发出的不同生物启发式鼻设计的NACA 4和6系列机翼，发现了NACA 4和6系列机翼的通用最佳鼻设计（海豚机翼）。