Mainstream Temperature Research Articles

Investigation on the suitability of conventional film hole under pulsed detonation incoming flow conditions

As a novel and efficient engine, the pulse detonation engine will increasingly demand advanced cooling technology. Film cooling, widely utilized in conventional aero engines, is also anticipated to be employed in pulse detonation engines. However, further investigation is required to assess the suitability of conventional film holes for pulse detonation engines. This study determines the cooling characteristics of a plate with a single film hole in a pulse detonation engine operating at a frequency of 30Hz through numerical calculations. The types of film holes considered include cylindrical, fan-shaped, laid-back, laid-back fan-shaped, and converging-slot holes, all of which have a diameter of 1 mm and an inclination angle of 30°. The single pulse detonation period is divided into stages: initiation and detonation wave propagation, gas exhaust, and refilling. During the initiation and detonation wave propagation stage, the film hole exhibits a significant backflow phenomenon, with the magnitude of gas backflow positively correlated with the outlet area of the film hole. Notably, the converging-slot hole experiences the least amount of gas backflow, with an exit area 33 % smaller than that of cylindrical holes and a corresponding 18 % reduction in backflow enthalpy. Throughout the initiation and detonation wave propagation stage, the backflow gas carries an enthalpy ranging from 0.43 J to 0.63 J into each individual film hole. In the gas exhaust stage, the blowing ratio increases over time as the mainstream pressure decreases, leading to a rapid decline in the film cooling effectiveness of the cylindrical and laid-back holes. The converging-slot holes have the largest film covering area, thus exhibiting the highest film cooling effectiveness, which is 53 % higher than that of the cylindrical hole. In the refilling stage, the mainstream temperature reaches the same level as the secondary flow temperature, rendering the consideration of the cooling characteristics of the film hole unnecessary. Under the conditions of this study, the converging-slot hole is found to be most suitable for cooling the pulse detonation engine.

Background radiation compensation calibration method for film cooling infrared temperature measurement based on BP neural network

The precise non-contact temperature measurement method is essential for studying gas turbine component heat transfer. While infrared thermal imaging provides high-resolution two-dimensional temperature fields, errors arise from the measurement environment's complexity, emissivity variations, and reflection radiation effects. This study utilizes BP neural networks to correct infrared radiation on gas film cooled plates. By modeling background radiation and analyzing infrared emission processes, factors influencing temperature distribution are identified. Experimental data from uncooled plate are used for network training. Experimental measurements were conducted on uncooled plates to obtain training data. A BP neural network was established based on Planck's law and the radiation transmission process to relate the mainstream temperature to the background radiation. Calibration analysis was performed based on experimental data from the cooled plate, achieving the restoration of the two-dimensional temperature field under multiple operating conditions and significantly reducing measurement errors. This method comprehensively considers the entire process of radiation transmission, thereby eliminating background radiation embedded in the infrared images. The obtained measurement results vividly depict the real temperature distribution, offered significant support for gas turbine engineering applications.

Study of design methods and heat transfer characteristics of combined cooling structure for turbine blades with turbine inter-vane burner

The turbine inter-vane burner can greatly increase the engine thrust but brings about a harsh thermal environment to the turbine blades. Fuel-air combined cooling structure is an effective way to solve the thermal protection problem of the blades. There is a lack of research on the thermal protection of turbine blades with turbine inter-vane burner, especially systematic research on the fuel–air combined cooling structure. In this paper, the design methods of the fuel–air combined cooling structure of turbine blades with turbine inter-vane burner are proposed, and one-dimensional empirical formulas are used to design specific parameters. The heat transfer characteristics of the designed combined cooling structure are numerically investigated and analyzed without turbine inter-vane combustion, where the mainstream temperature varies from 818 K to 1414 K, the cold air temperature ranges from 500 K to 700 K, and the mass flow rate of cold air changes from 0.005 kg/s to 0.02 kg/s. The results show that in the combined cooling structure with embedded fuel channels, the heat absorbed by fuel is mostly influenced by cold air temperature compared to mainstream temperature and mass flow rate of cold air. The proportion of fuel heat absorption to overall heat absorption decreases from 0.25 to 0.13 when mainstream temperature increases from 818 K to 1418 K, as the increase of mainstream temperature has a minimal effect on the heat flux of the fuel channels, but can significantly increase the overall heat absorption. The proportion of fuel heat absorption to the overall heat absorption changes from 0.15 to 0.31 when cold air temperature increases from 500 K to 700 K, as the increase of cold air temperature enhances the heat exchange between the fuel channels and the cold air but decreases the heat exchange between the mainstream and the cold air. Besides, the flow and heat transfer performance of the combined cooling structure of turbine blades with turbine inter-vane combustion is numerically studied. The results show that the temperature of blade and fuel channels are maintained within the safe range with turbine inter-vane combustion, providing research support for subsequent studies on the fuel–air combined cooling structure of turbine blades with turbine inter-vane burner.

Experimental research on high-temperature radiation characteristics of film-cooled plate of gas turbines

With the rise in pre-turbine temperature and advancements in cooling technology, the temperature gap between the hot-gas and the blades increases. This phenomenon accentuates the significance of high-temperature radiation. However, the relevant experiments available to provide quantitative assessments of radiation are limited because of the challenging task of designing, constructing, and operating a high-temperature radiation facility. In this study, a high-temperature radiation facility is constructed to study the measurement method of evaluating radiation. The radiative heat flux of film-cooled plate of gas turbines are quantified successfully through the presented infrared-thermocouple dual reference body measurement and regression technique based on thermocouple data. The two proposed methodologies can pave the way for novel research avenues in evaluating radiation of the guide vanes. It is found that the proportion of radiation to total heat flux decreases gradually as the wall temperature increases. When the mainstream temperature is 912 K and the coolant temperature is 303 K, the radiation constitutes 50 % of the total heat flux.

The mechanical characteristics and cooling performance of a turbine blade with non-homogeneous lattice structure

The turbine blade is working at a high rotation speed and under constant impact from the high-temperature and high-pressure mainstream, causing deformation and a reduction in working efficiency; at the same time, the mainstream temperature at the inlet is increasing to achieve a high heat efficiency. Therefore, there is a high demand for turbine blade cooling technology. In this study, the authors proposed replacing the traditional spoiler with a non-homogeneous lattice structure in the inner cavity of the high-pressure turbine blade. The turbine blade was then simulated and experimend in real-world conditions using numerical simulation software and manufactured actual blades, and the maximum deformation of the turbine blade was measured to assess the impact of the non-homogeneous lattice structure on the blade's strength. The findings are as follows: The maximum deformation of the turbine blade optimized with a non-homogeneous lattice structure is 9.91% less than that of the traditional turbine blade with a spoiler, and its deformation-weight ratio is 11.51% less than the latter; the optimized turbine blade has a large cooling area in the concave surface of the blade, which improves the air film cooling effect, the coverage area of gas film hole outlet flow rate has increased by 12.39%. Finally, the non-homogeneous lattice structure optimizes the inner cavity structure of the turbine blade and is useful for improving the turbine blade's structural design and air film cooling performance.

Research on blending combustion characteristics of coaxial injector of oxygen/methane engine

Aiming at the demand of oxygen/methane rocket engine for future reusable spacecraft, the design of oxygen/methane coaxial injector engine and the study of flow mixing and combustion characteristics were carried out. The flow field characteristics, flame structure size and heat release state changes under different fuel-oxygen momentum ratio of coaxial injector were investigated. The results show that the increase of fuel-oxygen momentum ratio in the cold flow state increases the influence of the mainstream flow on the flow in the combustion chamber, and the length of the vorticity shear layer also increases. With the increase of fuel-oxygen momentum ratio, the flame's lifting distance gradually decreases, the rate of methane needed to stabilize the flame in the shear layer is over twice that of oxygen. At this time, as this ratio increases, the flame expansion angle increases while its length decreases. Rich combustion in the return zone is suppressed, but there is still some impact on component distribution ahead of main heat release. With the increase of fuel-oxygen momentum ratio, the starting position of the high temperature zone gradually advances, and the increase of fuel-oxygen momentum ratio makes the mainstream temperature change significantly intensified. Within a fuel-oxygen momentum ratio range of 0.5–2, the alteration of this ratio has a significant impact on the temperature profile of the gas close to the wall. However, as the ratio increases, the effect of this change on the gas temperature diminishes significantly.

Uncertainty analysis of intra-module environmental stress parameter design in light use efficiency-based gross primary productivity estimation models

Terrestrial gross primary productivity is a key part in the carbon cycle, and the light use efficiency model is a widely employed tool for its estimation. However, since the specific designs of environmental stress parameters in light use efficiency models have obvious disparities, even for a single module (e.g., the temperature stress module), the uncertainties related to intra-module environmental stress parameters in light use efficiency models remain unclear. Thus, we gathered mainstream temperature and water stress parameters in light use efficiency models from existing publications, and employed a compatible framework to assess them from three perspectives: (1) identifying similarities and differences of environmental stress parameters; (2) evaluating the error propagation effect of input data under different environmental stress parameter combinations; and (3) assessing the generalization ability of environmental stress parameters. The results showed that the temperature stress parameters exhibited general homogeneity (shared 67.87% variance), while water stress parameters displayed noticeable internal variations (shared variance below 1.0%). Meanwhile, we revealed that the current flexible parameter combination method in light use efficiency model construction should be more cautious, since the flexible environmental stress parameter combinations would influence the error propagation effect from input data to final gross primary productivity estimations. In addition, our analysis found that the variance of environmental stress parameters was closely coupled to model estimation accuracy, and there was a positive relationship between the unique variance of temperature stress parameters and the ability of temperature stress parameters to describe gross primary productivity variation. Overall, the current environmental stress parameters demonstrated acceptable performance across most situations, except for biomes with high temperatures. This study provided a foundation towards the development of future parameter design, which may also inspire the application of empirical environmental factors in other gross primary productivity models.

Analysis of energy consumption of tobacco drying process based on industrial big data

To promote green upgrading, energy conservation, and consumption reduction in the tobacco manufacturing process, the process relationship between parameters of drying and the thermal energy consumption is qualitatively and quantitatively studied by using statistical analysis methods such as interpretable machine learning (RF, Extra-Trees, XGBoost, and LightGBM) and regression analysis. At the same time, the key indicators of energy saving and consumption reduction are concerned with various mathematical models. The thermal energy consumption during drying is mainly affected by the main steam temperature generated by the power workshop. 145 ∼ 275 MJ/h energy (for every 2 °C reduction in mainstream temperature) are saved in production based on main steam temperature regulation. Therefore, stable high-temperature steam and control systems are essential for green upgrades. By regulating the process parameters of other equipment, an energy-saving effect of 2.1 ∼ 2.2% (main steam temperature is 184 ∼ 188 °C) can be further achieved, which is about 81.9 ∼ 90.2 MJ/h. This research provides an improved guidance for green, energy-saving, and intelligent processing of tobacco manufacturing.

Effect of CMAS penetration behavior on stress evolution in TBCs under three-dimensional temperature gradients

CaO–MgO–Al2O3–SiO2 (CMAS) penetration is the primary failure mode of thermal barrier coating (TBC) film cooling systems, and therefore, understanding the CMAS penetration behavior and its effect on the internal stress evolution of TBCs is necessary. In this study, the effect of nonuniform CMAS penetration on the stress profile of a top ceramic (TC) coating layer was investigated under a nonuniform temperature field with three different mainstream temperatures (1561, 1623, and 1673 K). Further, a conjugate heat transfer numerical model was established to determine the temperature distribution in the TBCs with a gas-film cooling system. A phase-field model was adopted to study the CMAS penetration behavior. Moreover, the effects of CMAS penetration on the temperature distribution, growth rate of the thermal growth oxide (TGO), and residual stress are discussed. The CMAS penetration continuously eroded the TC layer, following the temperature distribution trend. CMAS penetration achieved temperature increments of 26.1, 35.1, and 40.3 K at the TC/TGO interface and TGO thickness differences up to 0.12, 0.26, and 0.37 μm after 500 h oxidation at the three mainstream temperatures. A significant increase in the residual stresses of the TBCs caused by CMAS penetration was observed. The von Mises stress increased from 243.7, 295.7, and 339.9 MPa to 367.0, 391.5, and 414.9 MPa, respectively. Driving forces for Mode I and Mode II interfacial cracks at the trailing edge of the cooling hole increased with CMAS penetration, and the increase in the mainstream temperature enhanced the driving forces.

Parametric analysis on combustion characteristics of hydrocarbon fueled parallel wall-jet inside a supersonic combustor

Using hydrocarbon fuel as cooling film is one of the most promising ways to thermally protect supersonic combustors and it can also be considered as a special combustion process. Parametric analysis is very important for increasing combustion efficiency of this special combustion process which is a parallel fuel wall-jet, and it is numerically investigated in this paper. It is found that, for parallel wall-jet combustion lacking near-field mixing enhancement because of the thermal protection purpose, decreasing equivalence ratio can lead to a significant increase in combustion efficiency since the wall-jet combustion efficiency is only determined by the shear mixing process. Moreover, under the constant equivalence ratio, increasing injection height from 0.67 mm to 2 mm can only slightly increase the combustion efficiency by 1.5% although it can reach a much better cooling performance. It is worth mentioning that, the effects of mainstream parameters on combustion efficiency present a step trend, self-ignition will occur as the mainstream temperature or Mach number reaches a certain value. And afterward, keep increasing mainstream temperature has little effect on the combustion efficiency since the mixing process keeps almost unchanged. Whereas, continuous reduction of mainstream Mach number will improve combustion efficiency by significantly enhancing mixing.

An LSTM-PSO-Based Predictive Strategy and Its Application in the Main Steam Temperature Control in Power Plants

We proposed an LSTM-PSO predictive controller strategy to overcome the large delay and strong disturbance during main steam temperature control. First, the long short-term memory (LSTM) network model was developed to forecast the future trend of mainstream temperature, and the deviation between the model output and the expected value after feedback correction was minimized by the particle swarm optimization (PSO) algorithm. Then, the LSTM-PSO predictive controller was taken as the primary controller to maintain the steam temperature of the coal-fired boiler. A comparative simulation with conventional PID cascade control and dynamic matrix controller strategies was given, and the test calculations indicate that the adjustment time was shortened and the overshoot was reduced. Finally, the LSTM – PSO predictive control strategy was deployed into the actual boiler operation process of a 300 MW coal-fired power plant, within 0.5 °C steady-state error and 2 °C dynamic error.

Numerical investigation of the effects of cooling jets on flow and cooling film characteristics downstream of air-cooled integrated flameholder

Integrated flameholders are widely used in advanced augmented/ramjet combustors to reduce the flow loss and weight of aero-engine. Air cooling is a credible method for restraining the increasingly raised wall temperature of flameholders with the increasing inlet temperature and operation cycle of combustors. In this work, an air-cooled integrated flameholder coupled with wall and radial parts was proposed based on our previous studies. Numerical investigations were performed to understand the influence of cooling jets on the flow and cooling film characteristics of air-cooled integrated flameholder in a simplified afterburner. Results suggest that the cooling jet angles α and β on the oblique and rear plates of the wall part mainly affect the flow and cooling film features in the wall backward-facing step, whereas the hole angle θ on the back wall of the radial part has a significant impact on both of the wall step region and downstream of the radial strut. Furthermore, flow analysis of the interaction of radial and wall cooling jets shows that when α and β remain unchanged, θ not only obviously determines the flow features downstream of the radial part but also has a great impact on the flow field in the step region. On the other hand, when θ is constant, α and β almost only change the flow field in the step region, whereas the flow field downstream of the radial part is mainly affected by the flow rate of radial cooling jets. Notably, since the cooling jets on the wall part can remove the flow resistance loss caused by the sudden contraction upon the oblique and rear plates, all air-cooled integrated flameholder schemes proposed in this work can diminish the total pressure loss of afterburner. The total pressure loss is almost unaffected by the varied α and β while θ=90∘ with the flow rate of radial cooling jets increasing. In addition, the total pressure loss is gradually increased with the mainstream velocity increasing and the mainstream temperature decreasing.

Thermal-hydraulic analysis of He–Xe gas mixture in 2×2 rod bundle wrapped with helical wires

Gas-cooled space reactor, which adopts He–Xe gas mixture as working fluid, is a better choice for megawatt power generation. In this paper, thermal-hydraulic characteristics of He–Xe gas mixture in 2 × 2 rod bundle wrapped with helical wires is numerically investigated. The velocity, pressure and temperature distribution of the coolant are obtained and analyzed. The results show that the existence of helical wires forms the vortexes and changes the velocity and temperature distribution. Hot spots are found at the contact corners between helical wires and fuel rods. The highest temperature of the hot spots reach 1600K, while the mainstream temperature is less than 400K. The helical wire structure increases the friction pressure drop by 20%–50%. The effect extent varies with the pitch and the number of helical wires. The helical wire structure leads to the reduction of Nusselt number. Comparing thermal-hydraulic performance ratios (THPR) of different structures, the THPR values are all less than 1. It means that gas-cooled space reactor adopting helical wires could not strengthen the core heat removal performance. This work provides the thermal-hydraulic design basis for He–Xe gas cooled space nuclear reactor.

熱力学的自己抑制効果と壁面加熱がノズル内キャビテーションに及ぼす影響

To clarify the thermal aspect of cavitating flow, cavitation experiments were conducted using a heated nozzle with different mainstream temperatures and heating conditions to evaluate two thermal effects that affect the cavity. The decrease in cavity length was observed due to the thermodynamic self-suppression effect by increasing the mainstream temperature, and the cavity length increased by heating from the wall. By comparing the variation of cavity length in the non-heated and heated conditions, the condition balancing the two thermal effect was found. Additionally, the response of each thermal effect to the mainstream temperature was also found. It was also shown that the required wall superheat to cancel out thermodynamic self-suppression effect reaches a maximum value when the mainstream temperature is around 70 °C. The experimental results were compared and discussed with the mathematical model values for the two thermal effects.

A numerical study of mist-air film cooling on a 3-D flat plate

PurposeThe purpose of this study is to explore the mist-air film cooling performance on a three-dimensional (3-D) flat plate. In mist-air film cooling technique, a small amount of water droplets is injected along with the coolant air. The objective is to study the influence of shape of the coolant hole and operating conditions on the cooling effectiveness.Design/methodology/approachIn this study, 3-D numerical simulations are performed. To simulate the mist-air film cooling over a flat plate, air is considered as a continuous phase and mist is considered as a discrete phase. Turbulence in the flow is accounted using Reynolds averaged Navier–Stokes equation and is modeled using k–e model with enhanced wall treatment.FindingsThe results of this study show that, for cylindrical coolant hole, coolant with 5% mist concentration is not effective for mainstream temperatures above 600 K, whereas for fan-shaped hole, even 2% mist concentration has shown significant impact on cooling effectiveness for temperatures up to 1,000 K. For given mist-air coolant flow conditions, different trend in effectiveness is observed for cylindrical and fan-shaped coolant hole with respect to main stream temperature.Research limitations/implicationsThis study is limited to a flat plate geometry with single coolant hole.Practical implicationsThe motivation of this study comes from the requirement of high efficiency cooling techniques for cooling of gas turbine blades. This study aims to study the performance of mist-air film cooling at different geometric and operating conditions.Originality/valueThe originality of this study lies in studying the effect of parameters such as mist concentration, droplet size and blowing ratio on cooling performance, particularly at high mainstream temperatures. In addition, a systematic performance comparison is presented between the cylindrical and fan-shaped cooling hole geometries.

Film-Cooling Effectiveness Downstream of a Single Row of Holes With Numberical Modeling in ANSYS-Fluent

With the increasing thrust of aero-engine, the temperature of turbine leading edge gradually exceeded the limit that materials can bear. Therefore, it is a common way to cool the turbine blades with a reasonable structure of film cooling. In this paper, the single exhaust film hole is taken as the main research object, and the effects of jet mass flow ratio, different temperature of mainstream and jet flow on the cooling effect are studied. The main research method is numerical modeling, and the modeling results are compared with the existing experimental results. The results show that the results have some error in jet’s flow situation and fluctuation in cooling efficiency, but there are still some errors in the calculation of heat transfer efficiency, which may be related to boundary layer separation phenomenon and the accuracy of the corresponding turbulence model.

Numerical simulation study of transpiration cooling with hydrocarbon fuel as coolant

Transpiration cooling is an advanced active thermal protection technology, which has been studied widely. The effects of cracking reaction on transpiration cooling are considered in this paper when n-decane is used as coolant. The porous wall temperature is reduced and the cooling efficiency is improved due to the cracking reaction. The cracking of n-decane produces a large number of small molecular products, and the random motion of the small molecular products increases the turbulent kinetic energy near the wall. The synergistic effect of the flow field and the total enthalpy near the porous wall is analyzed. The energy fluctuation caused by the cracking reaction is not enough to change the momentum distribution at the porous wall. The pressure increase caused by the small molecular gas generated by the cracking of n-decane can block the flow inside the porous media. The cooling effect brought by the cracking reaction is more obvious when increasing the coolant inlet temperature and the mainstream temperature.

Thermodynamic Suppression Effect of Cavitation Arising in a Hydrofoil in 140 °C Hot Water

Abstract The thermodynamic suppression effect of cavitation arising in a NACA0015 single hydrofoil is experimentally investigated in water at mainstream temperatures of T∞ = 20 °C to 140 °C in the present study. The cavity length at T∞ = 140 °C is shorter than that at T∞ = 20 °C at a constant cavitation number for all cavity patterns from inception to supercavitation. On the other hand, the cavity length at T∞ = 80 °C is slightly shorter than that at 20 °C in a certain region in which unsteady sheet-cloud cavitation occurs. This indicates that the thermodynamic suppression effect appears easily in unsteady cavitation. In addition, the temperature reduction inside cavities in water is accurately measured using thermistors, which are inserted from the sidewall directly into the cavity. The temperature measurement is performed at a mainstream temperature of less than 80 °C due to limitation of calibration for the sensor. The temperature reduction at 140 °C is then predicted from the measured cavity length. It is shown that the temperature reduction inside the cavity is approximately ΔT = 0.3 °C at T∞ = 80 °C and ΔT = 0.05 °C at T∞ = 20 °C under supercavitation conditions. The predicted temperature reduction inside the cavity is ΔT = 1.1 K at T∞ = 140 °C under supercavitation conditions. Finally, Fruman's prediction equation for ΔT is examined by fitting to the measured and predicted ΔT values with assuming a volume coefficient of evaporation CQ as a fitting parameter.

Errors Incurred in Local Convective Heat Transfer Coefficients Obtained through Transient One-Dimensional Semi-Infinite Conduction Modeling: A Computational Heat Transfer Study

In typical turbulent flow problems, detailed heat transfer coefficient (h) maps obtained through short-duration experiments are based on inverse heat transfer methods that take the wall temperatures measured via liquid crystals or infrared thermography as input, and an error minimization routine is adopted to determine the best value of h that satisfies the wall temperature temporal evolution under a certain change in fluid temperature. A common practice involves modeling the solid as a one-dimensional semi-infinite medium by selecting the solid material that has low thermal conductivity and low thermal diffusivity. However, in certain flow scenarios, the neglection of the lateral heat diffusion may lead to significant errors in the deduced h values. It is imperative to understand the reasons behind large errors that may be incurred by using the 1D heat conduction assumption in order to accurately determine high-resolution h maps for better heat exchanger designs in a wide range of thermal management applications. This paper presents a computational heat transfer study on different jet impingement scenarios to demonstrate the errors incurred in the determination of h when calculated under the assumption of one-dimensional (1-d) heat conduction into a solid. To this end, three different cases are studied: (a) single jet, (b) array jet (theoretical distribution), (c) array jet (experimental distribution), along with three different mainstream temperature evolution profiles representing step change, moderately fast transient and slow transient nature of flow driving the heat transfer in the solid. A known distribution of heat transfer coefficient (“true h”) for each of the three cases is considered, and three-dimensional transient heat diffusion equations were solved to populate temperatures of each node in the solid at every time step. It is found that stagnation zones’ h1d calculations were lower than the “true h” while the low heat transfer zones exhibited significantly higher h1d compared to the “true h”. For the array jet (experimental distribution) case, it was observed that errors can be as high as 10% in certain low heat transfer zones. Different data reduction procedures, configurations, and conditions explored in this study indicate that a suitable balance can be achieved if shorter time durations in transient experiments are used as a reference for tracking in h1d calculations to keep the deviations from the “true h” low.

Experimental and numerical study on the influence of pneumatic parameters on the flow structure in trapped vortex combustor

Flow field of combustors have been commonly used to help understand the combustion characteristics. In this study, the experimental and numerical investigation was carried out combined to study the effect of pneumatic parameters, such as the main stream Mach number, pressure ratio, and temperature, on the flow structure in a trapped vortex combustor This study aimed to investigate the influence of pneumatic parameters on the vortex center position and area of primary and secondary vortices in the cavity, and also study the distribution of axial and radial velocity in the cavity obtained by changing the inlet airflow temperature. The flow fields in the combustor cavity with the variation of main stream Mach number and pressure ratio were obtained by using Particle Image Velocimetry The results show that, a double-vortex pattern can be generated and tightly locked inside the cavity. Furthermore, the flow structure is significantly influenced by pressure ratio ( rp = 0.97–1.07) instead of mainstream Mach number (Ma = 0.13–0.17). Under the same Mach number, the location of vortex center in the main stream plane is moved with the appearance of the temperature gradient. Meanwhile, the velocity profiles indicate that the axial velocity is reduced as the temperature increase. This study provides a design guideline for combustion with the main stream and second stream, and also offers important reference value for the analysis of combustion performance in cavity.