Effect of Unsteady Lift Force on Vehicle Dynamics in Heave and Pitch Motion

Kawamura, Tetsuhiro; Ogawa, Atsushi

doi:10.4271/2014-01-0576

Cited by 5 publications

(3 citation statements)

References 10 publications

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“…This study employed an 8% scale (L = 0.376 m) simplified sedan model with the same shape as the model used by Kawamura and Ogawa (2014) shown in Fig. 2.…”

Section: Test Model and Experimental Setupmentioning

confidence: 99%

“…But it was shown that the ground speed has almost no influence on the dynamic effect, even when the ground speed is zero. Kawamura and Ogawa (2014) conducted a towing tank test using a one-degree-of-freedom oscillating apparatus with a six-component balance and numerical analysis. They quantified the unsteady lift characteristics of a simplified sedan model moving in the heaving and pitching directions.…”

Section: Introductionmentioning

confidence: 99%

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Effects of heaving and pitching motions on underside aerodynamics of a sedan vehicle

Maruyama

Shinji

Nonomura

et al. 2019

JFST

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Unsteady pressure distributions around a simplified sedan automobile model were investigated by conducting dynamic wind-tunnel testing using the newly developed forced oscillating apparatus, HEXA-X3, which can produce 6-degrees-of-freedom motion. The effects of heaving and pitching oscillation were investigated as the model simulated a vehicle running on a flat road at approximately 40 m/s and 1 Hz oscillation. The effects of the ground plate on unsteady pressure distributions over the model surfaces were measured while simulating heaving and pitching motion at Strouhal-number conditions similar to those for actual vehicles. The influence of the tubing on the frequency response of the pressure sensor was evaluated to be negligible by conducting a calibration experiment first. In the static case, the overall pressure distribution was consistent with that for a typical sedan, and the influence of the local relative flow velocity changes due to the contraction effect was observed in the underside of the model. In the forced oscillation tests, the effect of heaving and pitching motions on the flow around the underside was investigated. Effects of oscillation parameters, specifically amplitude and frequency, were investigated using the gain and phase-lag normalized by data from the steady model. Results of the test indicate that there is a characteristic distribution in pressure fluctuation, and the phenomena that become dominant in the flow around the underside vary according to location. The dynamic heaving motion was shown to change the pressure distribution, possibly due to changes in the effective angle of attack in addition to the static effect. The pitching test showed that a dynamic camber effect works in addition to those effects.

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“…This study employed an 8% scale (L = 0.376 m) simplified sedan model with the same shape as the model used by Kawamura and Ogawa (2014) shown in Fig. 2.…”

Section: Test Model and Experimental Setupmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Effects of heaving and pitching motions on underside aerodynamics of a sedan vehicle

Maruyama

Shinji

Nonomura

et al. 2019

JFST

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show abstract

“…The impact of such complex flow behaviour on vehicle stability at high speeds is challenging to predict (Okada et al, 2009; Kawakami et al, 2015). For example, changes in flow due to crosswinds, high-speed lane changes or braking, pitch or heave due to road indentations (and the shape of the vehicle itself) generate unsteady aerodynamic forces and moments that may cause vehicle instabilities (Baker, 1993; Baker & Reynolds, 1992; Howell & Baden Fuller, 2010; Kawamura & Ogawa, 2014; Macadam et al, 1990; Theissen, 2012). Under such conditions, the response of the vehicle is usually subjectively rated by the drivers, from excellent to unacceptable, to determine the quality of the vehicle dynamics.…”

Section: Introductionmentioning

confidence: 99%

Prediction of Drivers’ Subjective Evaluation of Vehicle Reaction Under Aerodynamic Excitations

et al. 2023

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Objective The objectives are to determine which quantities are important to measure to determine how drivers perceive vehicle stability, and to develop a regression model to predict which induced external disturbances drivers are able to feel. Background Driver experience of a vehicle’s dynamic performance is important to auto manufacturers. Test engineers and test drivers perform several on-road assessments to evaluate the vehicle’s dynamic performance before sign-off for production. The presence of external disturbances such as aerodynamic forces and moments play a significant role in the overall vehicle assessment. As a result, it is important to understand the relation between the subjective experience of the drivers and these external disturbances acting on the vehicle. Method A sequence of external yaw and roll moment disturbances of varying amplitudes and frequencies is added to a straight-line high-speed stability simulation test in a driving simulator. The tests are performed with both common and professional test drivers, and their evaluations to these external disturbances are recorded. The sampled data from these tests are used to generate the needed regression model. Results A model is derived for predicting which disturbances drivers can feel. It quantifies difference in sensitivity between driver types and between yaw and roll disturbances. Conclusion The model shows a relationship between steering input and driver sensitivity to external disturbances in a straight-line drive. Drivers are more sensitive to yaw disturbance than roll disturbance and increased steering input lowers sensitivity. Application Identify the threshold above which unexpected disturbances such as aerodynamic excitations can potentially create unstable vehicle behaviour.

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Improved Predictive Model of Drivers’ Subjective Perception of Vehicle Reaction under Aerodynamic Excitations

Kumar,

Sällström,

Sebben

et al. 2023

Int.J Automot. Technol.

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Effect of Unsteady Lift Force on Vehicle Dynamics in Heave and Pitch Motion

Cited by 5 publications

References 10 publications

Effects of heaving and pitching motions on underside aerodynamics of a sedan vehicle

Effects of heaving and pitching motions on underside aerodynamics of a sedan vehicle

Prediction of Drivers’ Subjective Evaluation of Vehicle Reaction Under Aerodynamic Excitations

Improved Predictive Model of Drivers’ Subjective Perception of Vehicle Reaction under Aerodynamic Excitations

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