Wind tunnel investigation of hemispherical forebody interaction on the drag coefficient of a D-shaped model

IF 1.2 4区工程技术 Q3 ENGINEERING, AEROSPACE Aircraft Engineering and Aerospace Technology Pub Date : 2024-09-17 DOI:10.1108/aeat-12-2023-0326

Suresh V., Kathiravan Balusamy, Senthilkumar Chidambaram

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Abstract

Purpose

An experimental investigation of hemispherical forebody interaction effects on the drag coefficient of a D-shaped model is carried out for three-dimensional flow in the subcritical range of Reynolds number 1 × 10⁵ ≤ Re ≤ 1.8 × 10⁵. To study the interaction effect, hemispherical shapes of various sizes are attached to the upriver of the D-shaped bluff body model. The diameter of the hemisphere (b₁) varied from 0.25 to 0.75 times the diameter of the D-shaped model (b₂) and its gap from the D-shaped model (g/b₂) ranged from 0.25 to 1.75 b₂.

Design/methodology/approach

The experiments were carried out in a low-speed open-circuit closed jet wind tunnel with test section dimensions of 1.2 × 0.9 × 1.8 m (W × H × L) capable of generating maximum velocity up to 45 m/s. The wind tunnel is equipped with a driving unit which has a 175-hp motor with three propellers controlled by a 160-kW inverter drive. Drag force is measured with an internal six-component balance with the help of the Spider 3013 E-pro data acquisition system.

Findings

The wind tunnel results show that the hemispherical forebody has a diameter ratio of 0.75 with a gap ratio of 0.25, resulting in a maximum drag reduction of 67%.

Research limitations/implications

The turbulence intensity of the wind tunnel is about 5.6% at a velocity of 18 m/s. The uncertainty in the velocity and the drag coefficient measurement are about ±1.5 and ±2.83 %, respectively. The maximum error in the geometric model is about ±1.33 %.

ractical implications

The results from the research work are helpful in choosing the optimum spacing of road vehicles, especially truck–trailer and launch vehicle applications.

Social implications

Drag reduction of road vehicle resulting less fuel consumption as well as less pollution to the environment. For instance, tractor trailer experiencing approximately 45% of aerodynamics drag is due to front part of the vehicle. The other contributors are 30% due to trailer base and 25% is due to under body flow. Nearly 65% of energy was spent to overcome the aerodynamic drag, when the vehicle is traveling at the average of 70 kmph (Seifert 2008 and Doyle 2008).

Originality/value

The benefits of placing the forebody in front of the main body will have a strong influence on reducing fuel consumption.

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半球形前体相互作用对 D 形模型阻力系数的风洞研究

目的在雷诺数 1 × 105 ≤ Re ≤ 1.8 × 105 的亚临界范围内，对半球形前体对 D 形模型阻力系数的相互作用效应进行了实验研究。为了研究相互作用效应，在 D 形崖体模型的上游附着了不同大小的半球形。半球的直径（b1）为 D 形模型直径（b2）的 0.25 至 0.75 倍，与 D 形模型的间隙（g/b2）为 0.25 至 1.75 b2。风洞配备了一个驱动装置，该装置有一个 175 马力的电机和三个螺旋桨，由一个 160 千瓦的变频驱动器控制。研究结果风洞结果表明，半球形前体的直径比为 0.75，间隙比为 0.25，最大阻力减少了 67%。速度和阻力系数测量的不确定性分别约为±1.5%和±2.83%。研究结果有助于选择公路车辆的最佳间距，特别是卡车拖车和运载火箭的应用。社会影响减少公路车辆的阻力可降低燃料消耗，减少对环境的污染。例如，牵引拖车约 45% 的空气阻力来自车辆前部。其他 30% 的阻力来自拖车底座，25% 来自车身底部的气流。当车辆以平均 70 公里/小时的速度行驶时，近 65% 的能量用于克服空气阻力（Seifert，2008 年；Doyle，2008 年）。

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来源期刊

Aircraft Engineering and Aerospace Technology 工程技术-工程：宇航

CiteScore

3.20

自引率

13.30%

发文量

168

审稿时长

8 months

期刊介绍： Aircraft Engineering and Aerospace Technology provides a broad coverage of the materials and techniques employed in the aircraft and aerospace industry. Its international perspectives allow readers to keep up to date with current thinking and developments in critical areas such as coping with increasingly overcrowded airways, the development of new materials, recent breakthroughs in navigation technology - and more.