Acoustic Heating Research Articles

Acoustic characteristics of looped-tube thermoacoustic refrigerators with external and in-built acoustic drivers: A comparative study.

Thermoacoustic refrigerators (TARs) are in the first place acoustic systems. It is indispensable to conduct an acoustic analysis of the entire system before a thermodynamic analysis of the thermoacoustic core. This study focuses on the acoustic characteristics of looped-tube TARs integrated with single (or dual) external (or in-built) acoustic driver(s). System-level acoustic models are established for the looped-tube TARs, and their acoustic performances are discussed and compared. Results show that looped-tube TARs with a single acoustic driver have a standing-wave acoustic field no matter whether the configuration is symmetric or not. The eigenmodes of the TAR are not influenced by the location of the external acoustic driver but are affected by the location of the in-built acoustic driver. New pairs of resonance and anti-resonance frequencies show up for TARs with an asymmetric configuration. Compared with looped-tube TARs with a single external (or in-built) acoustic driver, looped-tube TARs with dual external (or in-built) acoustic drivers have the same (or different) eigenmodes. A standing-wave acoustic field is present inside the loop only when the two acoustic drivers work in in-phase and anti-phase modes. At other phase differences between the two acoustic drivers, the acoustic field inside the loop becomes hybrid, containing both standing- and traveling-wave components. The theoretical methodology and analytical results in this study are valuable in comprehending the acoustic behavior of electrically-driven looped-tube TARs, providing useful guidelines for the active control of acoustic field and heat transport in the thermoacoustic core.

Dynamical Characterization of Thermoacoustic Oscillations in a Hydrogen-Enriched Partially Premixed Swirl-Stabilized Methane/Air Combustor

Abstract In this study, we systematically analyze the effects of hydrogen enrichment in the well-known PRECCINSTA burner, a partially premixed swirl-stabilized methane/air combustor. Keeping the equivalence ratio and thermal power constant, we vary the hydrogen percentage in the fuel. Successive increments in hydrogen fuel fraction increase the adiabatic flame temperature and also shift the dominant frequencies of acoustic pressure fluctuations to higher values. Under hydrogen enrichment, we observe the emergence of periodicity in the combustor resulting from the interaction between acoustic modes. As a result of the interaction between these modes, the combustor exhibits a variety of dynamical states, including period-1 limit cycle oscillations (LCO), period-2 LCO, chaotic oscillations, and intermittency. The flame and flow behavior is found to be significantly different for each dynamical state. Analyzing the coupled behavior of the acoustic pressure and the heat release rate oscillations during the states of thermoacoustic instability, we report the occurrence of 2:1 frequency-locking during period-2 LCO, where two cycles of acoustic pressure lock with one cycle of the heat release rate. During period-1 LCO, we notice 1:1 frequency-locking, where both acoustic pressure and heat release rate repeat their behavior in every cycle.

Using Amorphous CoB Alloy as Transducer to Detect Acoustic Propagation and Heat Transport at Interface

Acoustic oscillation provides useful information regarding the interfacial coupling between metal transducer layers and substrate materials. The interfacial coupling can be significantly reduced by a mechanically soft layer between the transducer and substrate. However, preserving a thin, soft layer at the interface during fabrication is often challenging. In this study, we demonstrate that an amorphous CoB alloy on top of a sapphire substrate can substantially amplify acoustic oscillations. By analyzing the attenuation of acoustic oscillations, we show that a thin, soft layer with a thickness of >2 ± 1 Å exists at the interface. The intermediate layer at the interface is further verified by investigating heat transport. By analyzing the slow decrease of the temperature of the transducer layer, we determine a thermal conductance of 35 ± 5 MW m−2 K−1 at the transducer/substrate interface. This low value supports the existence of a thin, soft layer at the interface. Our results demonstrate that an amorphous metal with B alloying effectively preserves the soft nature at the interface and detects the acoustic propagation and heat transport across it.

Chromospheric activity in 55 Cancri: II. Theoretical wave studies versus observations

ABSTRACT In this study, we consider chromospheric heating models for 55 Cancri in conjunction with observations. The theoretical models, previously discussed in Paper I, are self-consistent, non-linear, and time-dependent ab-initio computations encompassing the generation, propagation, and dissipation of waves. Our focus is the consideration of both acoustic waves and longitudinal flux tube waves amounting to two-component chromosphere models. 55 Cancri, a K-type orange dwarf, is a star of low activity, as expected by its age, which also implies a relatively small magnetic filling factor. The Ca ii K fluxes are computed (multi-ray treatment) assuming partial redistribution and time-dependent ionization. The theoretical Ca ii H+K fluxes are subsequently compared with observations. It is found that for stages of lowest chromospheric activity the observed Ca ii fluxes are akin, though not identical, to those obtained by acoustic heating, but agreement can be obtained if low levels of magnetic heating – consistent with the expected photospheric magnetic filling factor – are considered as an additional component; this idea is in alignment with previous proposals conveyed in the literature.

Nonlinear Dynamics of a Swirl-Stabilized Combustor under Acoustic Excitations: Influence of the Excited Combustor Natural Mode Oscillations

In this study, experimental measurements are performed on a swirl-stabilized combustor to study the nonlinear combustor dynamic characteristics under acoustic excitations. The imposed acoustic disturbances with different frequencies and amplitudes generated by a loudspeaker are applied to the combustion system. The acoustic pressure oscillations and heat release rate fluctuations are measured using acoustic pressure transducers and a photomultiplier tube equipped with a bandpass OH* filter, respectively. Various parametric studies are conducted to evaluate the effects of the equivalent ratio $$\phi$$ , amplitude Af, and frequency ff of the acoustic excitations on the combustor dynamics. The obtained results indicate that the combustor experiences frequency locking-in phenomenon accompanied by high amplitude acoustic oscillations when ff is close to the natural frequency fa of the combustor quarter-wave mode. Such physical phenomena are observed even for a low forcing wave amplitude. However, heat release rate fluctuations reach saturation at high amplitude excitations. Moreover, the combustor experiences super-harmonic resonances when ff is close to fa/2 or fa/3. Under such conditions, high amplitude excitations are required to stimulate the natural resonant mode, while the heat release rate fluctuations rarely reach saturation. Cross-correlation and cross-power spectral density analyses on the OH* chemiluminescence and acoustic pressure signals reveal that super-harmonic resonances are caused by “quasi-couplings” between the acoustic pressure and unsteady heat release. Further, the results demonstrate that the excited natural mode oscillations affect the acoustic wave characteristics at the inlet section, while they hardly influence the heat release rate fluctuations. The obtained results indicate that the equivalence ratio has a negligible effect on the combustor dynamics under forced conditions. Finally, discussions are provided to address the influences of the excited natural mode oscillations on the experimental measurements of the flame describing function (FDF). The achieved acoustic velocity disturbances at the injector outlet are suppressed by excited natural mode oscillations, which confine the velocity disturbance amplitude within a narrow range when ff matches fa. Hence, excited natural mode oscillations should be avoided in practice if we need to measure the FDF under a wide range of acoustic velocity amplitudes. The nonlinear characteristics of forced oscillations studied in this paper are crucial to the development of control strategy and FDF measurement.

Exploring Applicability of Acoustic Heat Transfer Enhancement Across Various Perturbation Elements

Abstract The requirements of improved heat transfer performance on turbine surfaces and internal cooling passages drive the research into exploring new methods for efficiency enhancements. The addition of ribbed structures inside the cooling ducts has proven to be most practical, which increases heat transfer from surfaces to fluid flow at the cost of some pressure loss. Many active and passive methods have been proposed for enhancing the heat transfer, where acoustic excitation has been recently shown to be an effective option. Moreover, the existing pressure fluctuations due to rotor–stator interactions can also be utilized as a source of excitation. However, the sensitivity of the phenomenon to various flow and geometric parameters has not been fully characterized. The present study investigates various aspects of convective heat transfer enhancement and turbulent flow modulation caused by acoustic forcing on separating and reattaching flow over isolated rib obstacles. A parametric study is conducted; rib obstacles of various sizes and shapes (including rectangular, squared, triangular, and semi-cylindrical) are installed in a low-speed, fully turbulent wind tunnel, and measurements are taken at different velocities and excitation frequencies. Static pressure and spatially resolved surface temperature measurements are performed to quantify the ramifications of acoustic excitation on the wetted wall. Within the favorable Strouhal number range of 0.1–0.25, an optimum value of 0.16 is observed. It is shown that triangular ribs are more prone to acoustic heat transfer enhancement than rectangular or cylindrical perturbations. A linear correlation between static pressure recovery rate and acoustic heat transfer enhancement is observed, which is invariant to change in size/shape of the rib as well as flow and excitation parameters.

Post-recombination effects in confined gases photoionized at megahertz repetition rates

Recombination-driven acoustic pulses and heating in a photoionized gas transiently alter its refractive index. Slow thermal dissipation can cause substantial heat accumulation and impair the performance and stability of gas-based laser systems operating at strong-field intensities and megahertz repetition rates. Here we study this effect by probing the pulse-by-pulse buildup of refractive index changes in gases spatially confined inside a capillary. A high-power repetition-rate-tunable femtosecond laser photoionizes the gas at its free-space focus, while a transverse-propagating probe laser interferometrically monitors the resulting time-dependent changes in refractive index. The system allows convenient exploration of the nonlinear regimes used to temporally compress pulses with durations in the ∼30 to ∼300 fs range. We observe thermal gas-density depressions, milliseconds in duration, that saturate to a level that depends on the peak intensity and repetition rate of the pulses, in good agreement with numerical modelling. The dynamics are independently confirmed by measuring the mean speed-of-sound across the capillary core, allowing us to infer that the temperature in the gas can exceed 1000 K. Finally, we explore several strategies for mitigating these effects and improving the stability of gas-based high-power laser systems at high repetition rates.

Heat dissipation and acoustic emission features of titanium alloys in cyclic deformation mode

The present work unveils the features of heat dissipation and acoustic emission accompanying the fatigue crack growth in a titanium alloy (Ti-0.8Al-0.8Mn and Ti Grade 2) using the compact tension and Charpy V-notch specimens. The quantitative measurements of the heat dissipation rate were carried out by an original heat flux sensor. The obtained results reveal that there exist two appreciably different stages of the crack propagation within the stable Paris regime. Relationships between the crack growth rate and the heat dissipation rate are proposed for both stages. The application of the non-supervised clustering algorithm to the continuously recorded acoustic emission signal helped to identify two dominant mechanisms of stress relaxation that occur ahead of the crack tip—mechanical twinning and crack opening. The correlation between the acoustic emission energy and heat dissipation was found to be a harbinger of the approaching transition from stable to unstable crack growth.

Low order modelling of thermoacoustic instabilities and intermittency: Flame response delay and nonlinearity

This paper investigates the simplifying assumptions used for deriving low order models of thermoacoustic instabilities and thermoacoustic intermittency in turbulent combustor. These models consists in self-sustained oscillators subject to parametric and additive stochastic forcing. The main aspects of the thermoacoustic dynamics investigated in the present work are the phase between acoustic pressure and heat release rate oscillations, and the nonlinearity ruling the saturation of the flame response. We propose a model of coupled acoustic oscillators subject to delayed nonlinear source term from the flame, with parametric and additive stochastic forcing. This model qualitatively reproduces the experimentally observed thermoacoustic dynamics, including the intermittency in the vicinity of supercritical Hopf bifurcations, as well as the full spectral signature of the acoustic pressure. It is also shown that a simpler model, consisting of a single Van der Pol oscillator, is capable of capturing the essential aspects of the thermoacoustic coupling at the fundamental oscillation frequency and can serve as a basis for an effective estimation of the system’s linear growth rate via output-only identification methods.

Synchronous temperature variation monitoring during ultrasound imaging and/or treatment pulse application: a phantom study.

Ultrasound attenuation through soft tissues can produce an acoustic radiation force (ARF) and heating. The ARF-induced displacements and temperature evaluations can reveal tissue properties and provide insights into focused ultrasound (FUS) bio-effects. In this study, we describe an interleaving pulse sequence tested in a tissue-mimicking phantom that alternates FUS and plane-wave imaging pulses at a 1 kHz frame rate. The FUS is amplitude modulated, enabling the simultaneous evaluation of tissue-mimicking phantom displacement using harmonic motion imaging (HMI) and temperature rise using thermal strain imaging (TSI). The parameters were varied with a spatial peak temporal average acoustic intensity (I spta ) ranging from 1.5 to 311 W.cm-2, mechanical index (MI) from 0.43 to 4.0, and total energy (E) from 0.24 to 83 J.cm-2. The HMI and TSI processing could estimate displacement and temperature independently for temperatures below 1.80°C and displacements up to ~117 μm (I spta <311 W.cm-2, MI<4.0, and E<83 J.cm-2) indicated by a steady-state tissue-mimicking phantom displacement throughout the sonication and a comparable temperature estimation with simulations in the absence of tissue-mimicking phantom motion. The TSI estimations presented a mean error of ±0.03°C versus thermocouple estimations with a mean error of ±0.24°C. The results presented herein indicate that HMI can operate at diagnostic-temperature levels (i.e., <1°C) even when exceeding diagnostic acoustic intensity levels (720 mW.cm-2 < I spta < 207 W.cm-2). In addition, the combined HMI and TSI can potentially be used for simultaneous evaluation of safety during tissue elasticity imaging as well as FUS mechanism involved in novel ultrasound applications such as ultrasound neuromodulation and tumor ablation.

Numerical Modeling and Performance Evaluation of Standing Wave Thermoacoustic Refrigerators with a Multi-Layered Stack

Thermoacoustic refrigerators have huge potential to replace conventional refrigeration systems as an alternative clean refrigeration technology. These devices utilize conversion of acoustic power and heat energy to generate the desired cooling. The stack plays a pivotal role in the performance of Standing Wave Thermoacoustic Refrigerators (SWTARs), as the heat transfer takes place across it. Performance of stacks can be significantly improved by making an arrangement of different materials inside the stack, resulting in anisotropic thermal properties along the length. In the present numerical study, the effect of multi-layered stack on the refrigeration performance of a SWTAR has been evaluated in terms of temperature drop across the stack, acoustic power consumed and device Coefficient of Performance (COP). Two different aspects of multi-layered stack, namely, different material combinations and different lengths of stacked layers, have been investigated. The combinations of four stack materials and length ratios have been investigated. The numerical results showed that multi-layered stacks produce lower refrigeration temperatures, consume less energy and have higher COP value than their homogeneous counterparts. Among all the material combinations of multi-layered stack investigated, stacks composed of a material layer with low thermal conductivity at the ends, i.e., RVC, produced the best performance with an increase of 26.14% in temperature drop value, reduction in the acoustic power consumption by 4.55% and COP enhancement of 5.12%. The results also showed that, for a constant overall length, an increase in length of side stacked material layer results in an increase in values of both temperature drop and COP.

Numerical Investigation of Influence of Entropy Wave on the Acoustic and Wall Heat Transfer Characteristics of a High-Pressure Turbine Guide Vane

As an indirect noise source generated in the combustion chamber, entropy waves are widely prevalent in modern gas turbines and aero-engines. In the present work, the influence of entropy waves on the downstream flow field of a turbine guide vane is investigated. The work is mainly based on a well-known experimental configuration called LS89. Two different turbulence models are used in the simulations which are the standard k-ω model and the scale-adaptive simulation (SAS) model. In order to handle the potential transition issue, Menter’s ð-Reθ transition model is coupled with both models. The baseline cases are first simulated with the two different turbulence models without any incoming perturbation. Then one forced case with an entropy wave train set at the turbine inlet at a given frequency and amplitude is simulated. Results show that the downstream maximum Mach number is rising from 0.98 to 1.16, because the entropy waves increase the local temperature of the flow field; also, the torque of the vane varies as the entropy waves go through, the magnitude of the oscillation is 7% of the unforced case. For the wall (both suction and pressure side of the vane) heat transfer, the entropy waves make the maximum heat transfer coefficient nearly twice as the large at the leading edge, while the minimum heat transfer coefficient stays at a low level. As for the averaged normalized heat transfer coefficient, a maximum difference of 30% appears between the baseline case and the forced case. Besides, during the transmission process of entropy waves, the local pressure fluctuates with the wake vortex shedding. The oscillation magnitude of the pressure wave at the throat is found to be enhanced due to the inlet entropy wave by applying the dynamic mode decomposition (DMD) method. Moreover, the transmission coefficient of the entropy waves, and the reflection and transmission coefficients of acoustic waves are calculated.

Acoustic streaming effect on flow and heat transfer in porous tissue during exposure to focused ultrasound

High-intensity focused ultrasound (HIFU) is a minimally invasive technique of regional treatment in which ultrasound waves are focused on targeted tissue. Nevertheless, the precise localization of the target area of HIFU ablation remains challenging. This study investigated acoustic pressure, fluid flow, and heat transfer in porous tissue during exposure to HIFU. The effects of the heat transfer model, tissue permeability, and exposure time on fluid flow and temperature distribution in the tissue were numerically investigated. Additionally, the heating-region shape and heating position were studied. The acoustic pressure, fluid flow, and temperature distributions in the porous tissue during exposure to HIFU were calculated using the numerical simulation of acoustic wave propagation and heat transfer models. The heat transfer models used were formulated based on the conventional bioheat model and porous media theory. With the porous media model, the temperature distributions were observed to be different from those of the conventional bioheat model; this was caused by the acoustic streaming effect. Permeability affected the flow pattern and temperature distribution in the tissue. In particular, tissue permeability also has a significant effect on the position of the target area and lesion shape within the tissue.

REDUCING OF EXTERNAL NOISE ARMED VEHICLE “DOZOR-B” APPLICATIONS TO DUMPING COATING

There has been a war in Ukraine for 6 years. In this regard, the production of military equipment has increased significantly, including. armored vehicles. Serious requirements are imposed on any military equipment. This paper focuses on the reduction of the external noise of the Dozor-B armored vehicle both in terms of ecology and in terms of camouflage. The technical characteristics of the mentioned armored car and its main sources of noise are briefly discussed. It is concluded that the body emits a significant level of noise, and therefore it is important to reduce the total external noise of the armored car by reducing the noise emitted by the body of the latter. The dissertation work of Krutolapov V.Ye. was analyzed. "A method of improving the vibroacoustic characteristics of the car body using vibration damping materials." The dissertation deals with the method of measuring the amplitude-frequency characteristic of a plate with a damping coating, called "obst". We have pointed out the disadvantages developed by Krutolapov V.Ye. bituminous coated plates and suggested their solution. A method of reducing the level of external noise of armored vehicles by coating their housings with a multilayer damping coating is proposed. The algorithm of calculation of the mentioned covering is developed. The choice of the necessary materials is made on the basis of their acoustic properties, heat resistance and cost. The number of coating layers is calculated based on the required acoustic effect, cost and weight of the structure. The acoustic efficiency of the developed three-layer damping coating was calculated, as well as the estimation of the external noise reduction of the Dozor-B armored car for a number of speeds of the latter on the main cycle on the road due to the application of this coating. Keywords: transport, armored car, armed forces, fire support machine, military equipment, engine, power unit, noise, camouflage, ecology, noise source, housing, acoustic efficiency, wave impedance, sound penetration coefficient, multi-layer vibration damping material.

Acoustofluidics along inclined surfaces based on AlN/Si Rayleigh surface acoustic waves

Conventional acoustofluidics are restricted to manipulation of droplets on a flat surface, and there is an increasing demand for acoustofluidic devices to be performed at inclined surfaces to facilitate multilayered microfluidic device design and enhance system compactness. This paper reports theoretical and experimental studies of acoustofluidic behaviors (including transportation/pumping and jetting) along inclined surfaces using AlN/Si Rayleigh surface acoustic waves (SAWs). It has been demonstrated that for droplets with volume smaller than 3 μL, they could be efficiently transported on arbitrary inclined surfaces. The gravity effect would play a more and more important role in uphill climbing with the increased inclination angle. When the inclination angle was increased up to 90°, a higher threshold power was needed to transport the droplet and the maximum droplet volume which can be pumped also reached its minimum value. Effects of surface inclination angle on droplet jetting angles could be neglected for their volumes less than 2 μL. Moreover, microfluidic and acoustic heating performances of AlN/Si SAWs were further studied and compared with those conventional ZnO/Si SAWs with the same electrode configurations.

Multifractal analysis of flame dynamics during transition to thermoacoustic instability in a turbulent combustor

Gas turbine combustors are susceptible to thermoacoustic instability, which manifests as large amplitude periodic oscillations in acoustic pressure and heat release rate. The transition from a stable operation characterized by combustion noise to thermoacoustic instability in turbulent combustors has been described as an emergence of order (periodicity) from chaos in the temporal dynamics. This emergence of order in the acoustic pressure oscillations corresponds to a loss of multifractality in the pressure signal. In this study, we investigate the spatiotemporal dynamics of a turbulent flame in a bluff-body stabilized combustor during the transition from combustion noise to thermoacoustic instability. During the occurrence of combustion noise, the flame wrinkles due to the presence of small-scale vortices in the turbulent flow. On the other hand, during thermoacoustic instability, large-scale coherent structures emerge periodically. These large-scale coherent structures roll up the wrinkled flame surface further and introduce additional complexity in the flame topology. We perform multifractal analysis on the flame contours detected from high-speed planar Mie scattering images of the reactive flow seeded with non-reactive tracer particles. We find that multifractality exists in the flame topology for all the dynamical states during the transition to thermoacoustic instability. We discuss the variation of multifractal parameters for the different states. We find that the multifractal spectrum oscillates periodically during the occurrence of thermoacoustic instability at the time scale of the acoustic pressure oscillations. The loss of multifractality in the temporal dynamics and the oscillation of the multifractal spectrum of the spatial dynamics go hand in hand.

Acoustic field alteration in a 100 Hz dual acoustic driver straight tube travelling wave thermoacoustic heat pump for thermoacoustic heat transport control

A dual acoustic driver thermoacoustic heat pump was constructed to investigate the effect of acoustic field control on travelling wave thermoacoustic heat transport at a frequency of 100 Hz. The acoustic field was controlled by varying the phase difference and magnitude between the two drivers. Variation of phase difference demonstrated the change of both acoustic power flow direction and standing-travelling wave characteristics. Maximum temperature differences obtained between the ends of the regenerator were 23 °C and 19 °C when the acoustic power was flowing in the negative and positive directions, respectively. It has been shown that matching impedances on the cold and hot side of the regenerator influence the thermoacoustic heat pumping characteristics. Where monodirectional acoustic flow was observed on both sides of the regenerator, the impedance angles also coincided well. Variation of magnitude displayed a trend in which activation of an opposing acoustic driver at weaker power enhanced acoustic power flow and heat transport. A maximum temperature difference between the hot and cold sections of 23 °C is obtained when the input electric power of the opposing acoustic driver was 17% of the power of the initial acoustic driver where the impedances and impedance angles on both ends of the regenerator are matched but the acoustic field travelling wave characteristics are still sufficient for travelling wave device operation.

Acoustic Radiation Force Impulse Imaging Using Displacements of Lateral Dimension

Acoustic radiation force (ARF) induced elasticity imaging is usually used to obtain the elastic properties of media by detecting the induced displacement at the focal point. However, the ARF induced displacement response actually appears not only at the focal point, but also in lateral dimension at the focal depth. The relationship between the stiffness of media and the axial-directional displacements in lateral dimension at the focal depth has been analyzed through theoretical derivation, simulation and experimental verification. The results demonstrate that the maximum displacement in lateral dimension is inversely proportional to the lateral distance from the currently estimated point to the focal point. Therefore, the maximum displacement in lateral dimension at the focal depth is capable of estimating the elastic properties of the media. Based on this conclusion, an ARF impulse imaging method using displacements of lateral dimension is proposed. The induced displacements at the focal point as well as in the lateral dimension at the focal depth are detected under only the focal point excited. In this way, the proposed imaging method is expected to broaden the ARF impulse imaging region from the focal point to a larger region in the lateral dimension while reducing patient acoustic exposure and transducer heating.

Geonics (Geomimetics) as a Theoretical Approach for Designing and Production of Natural-Like Heat-Insulating Structurally and Composites with Acoustic Properties

Today, the use of thermal and acoustic insulation and energy loss prevention is one of the topics in the world. As presented by this research, it can be used for the technogenic parts and composite materials of different gens, to make green composite structures of different functionality (heat saving structurally, and acoustic without satisfying the cost and structure performance. These structures are used to prevent from unwanted heat and noise and safe existence which includes proper acoustic system, heat and humidity comfort conditions, environmental safety, and other comfort systems.

On the mechanism of open-loop control of thermoacoustic instability in a laminar premixed combustor

We identify mechanisms through which open-loop control of thermoacoustic instability is achieved in a laminar combustor and characterize them using synchronization theory. The thermoacoustic system comprises two nonlinearly coupled damped harmonic oscillators – acoustic and unsteady heat release rate (HRR) field – each possessing different eigenfrequencies. The frequency of the preferred mode of HRR oscillations is less than the third acoustic eigenfrequency where thermoacoustic instability develops. We systematically subject the limit-cycle oscillations to an external harmonic forcing at different frequencies and amplitudes. We observe that forcing at a frequency near the preferred mode of the HRR oscillator leads to a greater than 90 % decrease in the amplitude of the limit-cycle oscillations through the phenomenon of asynchronous quenching. Concurrently, there is a resonant amplification in the amplitude of HRR oscillations. Further, we show that the flame dynamics plays a key role in controlling the frequency at which quenching is observed. Most importantly, we show that forcing can cause asynchronous quenching either by imposing out-of-phase relation between pressure and HRR oscillations or by inducing period-2 dynamics in pressure oscillations while period-1 in HRR oscillations, thereby causing phase drifting between the two subsystems. In each of the two cases, acoustic driving is very low and hence thermoacoustic instability is suppressed. We show that the characteristics of forced synchronization of the pressure and HRR oscillations are significantly different. Thus, we find that the simultaneous characterization of the two subsystems is necessary to quantify completely the nonlinear response of the forced thermoacoustic system.