Methods to control low frequency pulsation in open-jet wind tunnel

Wang, Yigng; Yang, Z.; Li, Qilang

doi:10.1016/j.apacoust.2012.01.002

Cited by 9 publications

(8 citation statements)

References 6 publications

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“…Commonly used passive control measures include (i) the incorporation of a vortex generator at the jet nozzle [2][3][4]8,9,16,23,49,[51][52][53][54][55], (ii) optimization of the configuration of the collector, which includes shape optimization [4,6,17,21,23,31,49,56,57] and the addition of a breathing gap [4,6,7,14,15,21,58,59], (iii) the introduction of resonant chambers (Helmholtz resonators) connected to the plenum or the wind tunnel circuits [31,55,60], and (iv) modifying the wind tunnel circuits [9,11,19].…”

Section: Suppression Methods For Low-frequency Pressure Fluctuationmentioning

confidence: 99%

“…The low-frequency pressure fluctuations involve several factors, including the structural modes of the wind tunnel, instability of the jet shear layer, fluid-structure interaction, vortex-acoustic interaction, and acoustic propagation. The phenomenon of low-frequency pressure fluctuations in different wind tunnels often involves different excitation mechanisms, which poses challenges to the theoretical prediction and design of control methods [5,8,16,26,[28][29][30][31][32].…”

Section: Mechanism Of Low-frequency Pressure Fluctuationmentioning

confidence: 99%

“…The primary source of excitation for low-frequency pressure fluctuations in open-jet wind tunnels is the feedback loop resulting from the interaction between the jet and the collector [5,8,16,26,30,31], commonly referred to in the literature as edgetone. As the jet shear layer progresses downstream, large-scale vortex structures are generated as a result of the Kelvin-Helmholtz instability [33].…”

Section: Excitation Source Of Low-frequency Pressure Fluctuationmentioning

confidence: 99%

See 2 more Smart Citations

Review of Mechanisms and Suppression Methods for Low-Frequency Pressure Fluctuations in Open-Jet Wind Tunnels

Jin,

Deng,

Wang

et al. 2023

Applied Sciences

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Low-frequency pressure fluctuations are common in open-jet wind tunnels, affecting test accuracy and posing safety risks to the wind tunnels. These oscillations can be caused by different mechanisms in different wind tunnels, and it is often necessary to identify the specific mechanism responsible for the oscillation and develop appropriate control methods. This paper presents a comprehensive review of the current state of research on low-frequency pressure fluctuations in subsonic open-jet wind tunnels, with a particular emphasis on their generation mechanisms and control strategies. The primary source of excitation is attributed to the edgetone feedback formed by the impingement of the jet on the collector. The sound wavelength corresponding to the edgetone frequency is close to that of the plenum scale, facilitating resonance with both plenum-associated vibration modes and specific-order standing wave modes within the circuit loop, resulting in significant low-frequency pulsations. Passive control methods such as nozzle vortex generators and collector breathing gaps have been extensively employed due to their cost-effectiveness and efficiency. The concluding section highlights some unresolved issues that require further investigation in this field.

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Section: Suppression Methods For Low-frequency Pressure Fluctuationmentioning

confidence: 99%

Section: Mechanism Of Low-frequency Pressure Fluctuationmentioning

confidence: 99%

Section: Excitation Source Of Low-frequency Pressure Fluctuationmentioning

confidence: 99%

See 1 more Smart Citation

Review of Mechanisms and Suppression Methods for Low-Frequency Pressure Fluctuations in Open-Jet Wind Tunnels

Jin,

Deng,

Wang

et al. 2023

Applied Sciences

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“…The authors put forward two new control methods: a Helmholtz resonator and addition pipes connected with airline of wind tunnel. They can keep a stable level in entire velocity range and the method of addition airline has been applied to control the low frequency pulsation of the first aerodynamic and aero-acoustic automotive wind tunnel in China (Wang, Yang, Li 2012).…”

Section: Introductionmentioning

confidence: 99%

Effects of Reinjection on Flow Field of Open Jet Automotive Wind Tunnel Test Section

Dai

Zhong

et al. 2018

JAFM

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The distributions of axial static pressure coefficient and flow fluctuation in the test section which affect aerodynamic measurement in an open jet wind tunnel is presented. In this paper, the flow characteristics of the open jet automotive wind tunnel with passive reinjection and active reinjection were simultaneously investigated by experimental and numerical approaches. The axial static pressure coefficient variations can be reduced by passive or active reinjection, and recycle flow returns to the test section from the loophole is the main reason. The more mass flow rate improves the effect. Meanwhile, it is found that the improvement of the axial static pressure coefficient by reinjection is always better in the condition of 0° collector angle. The turbulence intensity in the collector angle of 15° is lower than that of 0°, and the reinjection increases the turbulence intensity near the collector. The increase of the turbulence intensity by active reinjection in the collector angle of 0° is greater than the collector angle of 15° for the 3.28° diffusion angle. There are some peaks emerging at the frequencies of 40 Hz and 50 Hz, which indicates that the flow field fluctuations may have induced structural vibration. The peaks at several frequencies increase when the passive and active reinjection are conducted, and the increase of peak is correlate with the increase of the reinjection flow rate. Due to the reduction of average static pressure coefficient and increase of flow fluctuations, the application of passive and active reinjection should be considered at the same time.

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“…In addition, the results by Nishi et al [ 34 ] confirmed a good agreement between target and measured turbulence parameter profiles by using the time-lag modification method. In a more recent study, Wang et al [ 35 ] addressed the control of the low-frequency pulsations that affect both the aerodynamics and the acoustic measurements in an open-circuit wind tunnel by adjusting the angles of the collector flaps and drilling an opening in the test section chamber above the nozzle. In another contribution, Li et al [ 36 ] proposed a hybrid fuzzy-PID control system for the cantilever beam structure that supports the scale models in order to avoid the drawbacks caused by the low-frequency resonant vibration resulting from the natural frequency induced by the flow.…”

Section: Introductionmentioning

confidence: 99%

An Auto-Tuning PI Control System for an Open-Circuit Low-Speed Wind Tunnel Designed for Greenhouse Technology

Espinoza

Valera

Torres

et al. 2015

Sensors

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Wind tunnels are a key experimental tool for the analysis of airflow parameters in many fields of application. Despite their great potential impact on agricultural research, few contributions have dealt with the development of automatic control systems for wind tunnels in the field of greenhouse technology. The objective of this paper is to present an automatic control system that provides precision and speed of measurement, as well as efficient data processing in low-speed wind tunnel experiments for greenhouse engineering applications. The system is based on an algorithm that identifies the system model and calculates the optimum PI controller. The validation of the system was performed on a cellulose evaporative cooling pad and on insect-proof screens to assess its response to perturbations. The control system provided an accuracy of <0.06 m·s−1 for airflow speed and <0.50 Pa for pressure drop, thus permitting the reproducibility and standardization of the tests. The proposed control system also incorporates a fully-integrated software unit that manages the tests in terms of airflow speed and pressure drop set points.

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Methods to control low frequency pulsation in open-jet wind tunnel

Cited by 9 publications

References 6 publications

Review of Mechanisms and Suppression Methods for Low-Frequency Pressure Fluctuations in Open-Jet Wind Tunnels

Review of Mechanisms and Suppression Methods for Low-Frequency Pressure Fluctuations in Open-Jet Wind Tunnels

Effects of Reinjection on Flow Field of Open Jet Automotive Wind Tunnel Test Section

An Auto-Tuning PI Control System for an Open-Circuit Low-Speed Wind Tunnel Designed for Greenhouse Technology

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