Unsteady Force and Flow Features of Single and Tandem Wheels

Abstract

Wind-tunnel experiments are presented in this paper for two different models, single wheel and tandem wheels. The tests are performed in the 2.1 m × 1.5 m wind tunnel at the University of Southampton. The aims of the experiment are to gain a better understanding of the flow past simple landing-gear components and to generate a CFD validation database. Since the model is designed to study basic landing-gear components, the wheel geometry is simplified, with no detailed elements in the assembly. The tandem-wheel configuration is formed of two in-line wheels that can be tested at different inter-axis distances and various angles of attack. Mean and unsteady data of aerodynamic loads and on-surface pressures are measured. A vibration test is performed in situ on the model assembly to validate the unsteady-load measurements. Particle Image Velocimetry (PIV) is used to acquire the velocity fields in the wake downstream of the model. The results highlight the low sensitivity of the measured quantities to the three versions of the wheel hub on the single wheel. The mean drag coefficients of the tandem wheels show a low sensitivity to the inter-axis distance, which has stronger effects on the mean lift coefficients and the unsteady aerodynamic loads. The angle of attack determines relevant changes in both mean and unsteady quantities. The pressures on the wheel surface are used for gaining a better understanding of the flow regimes and the effect of tripping the flow. Additionally, the PIV data are used to compare the velocity profiles in the wake and identify the wake vortical structures.

Unsteady aerodynamics of single and tandem wheels

“…Details of the tests with various tripping devices and wheel covers other than the flat cover are given in Spagnolo et al [27].…”

“…5 (more details can be found in Spagnolo et al [27]). The tripping technique used is a zig-zag tape on the front part of the wheel.…”

“…The phenomenon is expected to be related with the transitional flow, because the tripped configurations do not show the same feature. [27] In Figure 17, the pressure coefficients C p of the three tandem-wheel configurations are compared to analyse the effect of the inter-axis distance and the installation angle. The two cases with α = 0 deg show differences in mean values only in the fore part of the rear wheel.…”

“…To the authors' knowledge, it is the first time that the unsteady tests performed in the experiments were conducted. The studies are a part of a large study including tests, analysis and numerical simulations [27,26]. The overall objective of the study is to move the prediction of aerodynamic forces to a more mature stage in terms of accuracy and efficiency.…”

Numerical Simulations of Single and Tandem Wheels for Aerodynamic Loads Prediction

“…This study aims at identifying and predicting the flow features of simple components. It concentrates on DDES simulations of scaled landing-gear wheels in single and tandem configuration that were experimentally investigated in previous works within the same project (Spagnolo et al 19 ). The wheels in tandem configuration represent half of a four-wheel bogie without any interference from struts or doors.…”