Steady-state Temperature Research Articles

Kinetic simulations comparing quasi-parallel and quasi-perpendicular piston-driven collisionless shock dynamics in magnetized laboratory plasmas

Magnetized collisionless shocks are common in astrophysical systems, and scaled versions can be created in laboratory experiments by utilizing laser-driven piston plasmas to create these shocks in a magnetized background plasma. A key parameter for these experiments is the angle θB between the shock propagation direction and the background magnetic field. We performed quasi-1D piston-driven shock simulations to explore shock formation, evolution, and key observables relevant to laboratory experiments for a range of shock angles between θB=90° to θB=30°. Our results show that the spatial and temporal scales of shock formation for all angles considered are similar when expressed in terms of the perpendicular component of the magnetic field. In a steady state, ion and electron temperatures become more isotropic, and the electron-to-ion temperature ratio is higher for smaller θB. At θB=30°, ion heating parallel to the magnetic field becomes dominant, associated with more ions being reflected at one discontinuity and subsequently trapped by the next discontinuity due to shock reformation.

Ultrahigh-speed absolute temperature sensing using ferroelectric HfO2 enabled by transient negative differential capacitance.

Conventional ferroelectric polarization-driven temperature sensors, like pyroelectric sensors, often face challenges such as slow response times, limited compatibility with conventional nanoelectronics, and inability to operate under constant temperature conditions. These shortcomings hinder their adaptability to a broad range of applications, especially when compared to thermal and optical sensors. To address these challenges, we introduce a proof-of-concept methodology that enables ferroelectric-based pyroelectric sensors to measure absolute temperatures with high accuracy and speed. Specifically, we demonstrate that a perturbation pulse (+0.8 V, duration = 180 ns) can serve as an effective probe for quantifying both absolute and dynamic temperatures across ferroelectric hafnium zirconium oxide (HZO) nanolaminates. The device demonstrates an ultrafast response time of ∼50 nanoseconds, offering one million readings per second and a temperature sensing accuracy comparable to the state-of-the-art temperature sensing accuracy of 1.0 K. The observed performance is attributed to the temperature-dependent change of transient negative differential capacitance and effective ferroelectric polarization of HZO. For potential applications, we successfully integrated the sensor with a commercially available universal serial bus interface, thereby demonstrating real-time temperature monitoring during data transfer and environmental heating activities. Our research significantly broadens the range of applications for pyroelectric sensors for both steady-state and rapid dynamic temperature measurements.

Mass Sensing by Symmetry Breaking and Mode Localization in a System of Parametrically Excited Microbeam Resonators

In this work, we study the nonlinear dynamics of a mode-localized mass detector. A system of equations is obtained for two weakly coupled beam resonators with an alternating electric current flowing through them and taking into account the point mass on one of the resonators. The one-dimensional problem of thermal conductivity is solved, and a steady-state harmonic temperature distribution in the volume of the resonators is obtained. Using the method of multiple scales, a system of equations in slow variables is obtained, on the basis of which instability zones of parametric resonance, amplitude-frequency characteristics, as well as zones of attraction of various branches, are found. It is shown that in a completely symmetrical system (without a deposited particle), the effect of branching of the antiphase branch of the frequency response is observed, which leads to the existence of an oscillation regime with different amplitudes in a certain frequency range. In the presence of a deposited particle, this effect is enhanced, and the branching point and the ratio of the amplitudes of oscillations of the resonators depend on the mass of the deposited particle.

Heat transfer comparison investigation of the permanent magnet synchronous motor for electric vehicles based on the BEM and the FEM

In the field of heat transfer in permanent magnet synchronous motors (PMSM) for electric vehicles, the boundary element method (BEM) has been applied for the first time to calculate the steady-state temperature of the PMSM with a spiral water-cooled system. In this investigation, the boundary-integration equation for the steady-state heat transfer problem of a water-cooled PMSM is first derived on the basis of thermodynamic theory, and the system of constant coefficient differential equations is obtained by discretizing its boundaries, while the temperature results obtained from the BEM are compared with the finite element method (FEM) results. Furthermore, the temperature distribution and heat transfer characteristics obtained from the FEM and BEM were verified twice using the PMSM prototype and test platform. The results show that the maximum relative error between the temperature calculation results of FEM and BEM is 1.97%, and the maximum relative error between the results of BEM and the test does not exceed 3%, which finally verifies the validity and accuracy of BEM in solving the heat transfer problems of water-cooled PMSM.

Performance-Based Design Assessment of Temperature Tenability Condition in a Hotel Atrium

Fire safety risk assessment to prevent loss of human life and property is necessary for complex structures where the traditional prescriptive designs are inapplicable. Maintaining tenable temperature conditions is essential for the safe evacuation of building occupants. This study considered British Standards (BS) 7974 and the Code of Practice for Fire Precautions in Buildings to analyze the temperature tenability conditions in the hotel atrium through a performance-based design approach. Further, the Computational Fluid Dynamics (CFD) code, Pyrosim, a Graphical User Interface (GUI) of the Fire Dynamics Simulator (FDS), was utilized to simulate a constant Heat Release Rate (HRR) steady state design fire of 5 Megawatts (MW) igniting from the hotel brasserie (ground floor) within the atrium. The researcher used the big design fire of 5MW to generalize the results to similar fires in similar structures. The objective was to conduct a fire safety risk assessment to prevent loss of property and fatalities by activating a smoke management control system with a ‘what if’ condition when the fire suppression system failed to start. Temperature data was collected through the statistical steady state profile, smoke layer temperatures, thermocouples, and 2-dimensional slice temperature recordings. The ground floor, the fire source, was found to have untenable conditions for human survival with temperatures above 2250C, as confirmed by thermocouple and steady-state temperature profile readings. Other floors demonstrated tenable conditions for human survival with temperatures below 400C due to the effect of natural vents and mechanical extractors, which extracted the hot smoke at a rate of 15m/s. The temperature recordings from this study compared well with those from Chew and Liew’s (2000) Computational Fluid Dynamics results, which had fire igniting within the atrium, without sprinklers, and had mechanical extraction fans and a constant Heat Release Rate of 5 Megawatts (MW). The results indicated that the smoke control management system maintained tenable temperature conditions within the hotel atrium, even without the fire suppression system through sprinklers. Considering the design fire size was 5 MW, which was significantly big, the results could be generalized for other hotels or structures with similar designs.

Eco-friendly preparation and characterization of high-performance electrothermal graphene-AgNPs/lignocellulose composites.

Graphene-based (Gr-based) electrothermal heaters, due to their light weight, low electrical resistance, high thermal conductivity, and easy accessibility, have attracted widespread attention in the field of electrothermal heating. To achieve a high steady-state temperature in electrothermal heaters under low voltage, here we constructed a Gr-based film with low electrical resistance. Firstly, we employed non-toxic vitamin C to reduce silver nitrate for the in situ chemical deposition of silver nanoparticles (AgNPs) on the Gr surface. The SEM results confirmed that the AgNPs were uniformly deposited on the Gr surface. The synergistic interaction between AgNPs and Gr provided high-speed electrons transport paths for the film. On the other hand, we employed biodegradable lignocellulose fiber (LCF) as a dispersant and film-forming agent. The aromatic ring structure of LCF interacts with Gr via π-π interactions, aiding the dispersion of Gr in aqueous solutions. SEM results revealed that LCF permeated through the surfaces and interstices of the two-dimensional Gr sheets, providing mechanical support for the composite film. This approach enables the creation of freestanding Gr-AgNPs/LCF electrothermal composites. The resistivity and electrothermal results demonstrated that the obtained 20 wt% Gr-based composite film possessed low electrical resistance (5.4 Ω sq-1) and exhibited an outstanding saturated temperature of 214 °C under a very low input voltage of 7 V. The preparation method of this Gr-based composite film is simple, easy to operate, and environmentally friendly, providing a new reference for the preparation of eco-friendly and high-performance resistance heating electronics.

Highly oriented BN-based TIMs with high through-plane thermal conductivity and low compression modulus.

In the pursuit of effective thermal management for electronic devices, it is crucial to develop insulation thermal interface materials (TIMs) that exhibit exceptional through-plane thermal conductivity, low thermal resistance, and minimal compression modulus. Boron nitride (BN), given its outstanding thermal conduction and insulation properties, has garnered significant attention as a potential material for this purpose. However, previously reported BN-based composites have consistently demonstrated through-plane thermal conductivity below 10 W m-1 K-1 and high compression modulus, whilst also presenting challenges in terms of mass production. In this study, low molecular weight polydimethylsiloxane (PDMS) and large-size BN were utilized as the foundational materials. Utilizing a rolling-curing integrated apparatus, we successfully accomplished the continuous preparation of large-sized, high-adhesion BN films. Subsequent implementation of stacking, cold pressing, and vertical cutting techniques enabled the attainment of a remarkable BN-based TIM, characterized by an unprecedented through-plane thermal conductivity of up to 12.11 W m-1 K-1, remarkably low compression modulus (55 kPa), and total effective thermal resistance (0.16 °C in2 W-1, 50 Psi). During the TIMs performance evaluation, our TIMs demonstrated superior heat dissipation capabilities compared with commercial TIMs. At a heating power density of 40 W cm-2, the steady-state temperature of the ceramic heating element was found to be 7 °C lower than that of the commercial TIMs. This pioneering feat not only contributes valuable technical insights for the development of high-performance insulating TIMs but also establishes a solid foundation for widespread implementation in thermal management applications across a range of electronic devices.

Design and Optimization of an Interior Permanent-Magnet Synchronous Motor for Aircraft Drive Application

The torque performance of the interior permanent-magnet synchronous motor (IPMSM) must be further improved to satisfy the growing demand of aircraft drive application. To this end, this article focuses on the design optimization of the IPMSM structure in the aircraft drive systems to improve the torque density and reduce the torque ripple. A special fractional-slot winding and ∇-type magnetic-pole rotor topology are proposed as the optimized IPMSM structure compared with the structure of an existing motor. The simulations of the original and optimized structures at different current values reveal the variance of the torque in the average and ripple, mechanical and external characteristics, efficiency and steady-state temperature. The performance of an optimized prototype is analyzed by experimental testing, and the results show that an optimized motor has a higher torque density and lower torque ripple than the original one at the same speed and rated power, but it also has a higher temperature rise. However, the temperature rise value is acceptable in the experimental testing condition, so the validity of the design optimization method for the proposed structure is verified.

Conjugate heat transfer characteristics numerical simulation on steam generator tube of lead-cooled fast reactor

The safety assessment of the Steam Generator Tube Rupture (SGTR) accident is a crucial step in the design process of the Lead-cooled Fast Reactor (LFR). To begin with, it is necessary to simulate the steady-state heat transfer of the LFR Heat Exchanger (HX) in order to determine the initial conditions of the SGTR accident. In this study, the heat transfer characteristics of the fluids on both sides of the LFR HX are analyzed. The appropriate models are modified based on the heat transfer characteristics of liquid metal and boiling water. The accuracy of the boiling models is verified by comparing the simulation results with the outcomes of boiling heat transfer experiments. Additionally, the simulation results are compared with the results obtained from ATHLET calculation and empirical formulas. On the secondary side, the supercooled water undergoes heating until it reaches the superheated steam phase. The preheating section spans from 0 to 600 mm, the saturated boiling section ranges from 600 to 3000 mm, and the superheating section extends from 3000 to 6600 mm. Ultimately, the distributions of steady-state temperature, pressure, and vapor volume fractions of the LFR HX are determined, providing the necessary initial conditions for the occurrence of the SGTR accident.

A new LTNE analysis process for predicting the steady-state temperature distribution in a fixed bed of randomly packed mono-sized rough spheres based on pore-scale simulations

A new analysis process for the LTNE (local thermal non-equilibrium) model to solve for steady-state, fully-developed convection in mono-sized-sphere packed bed is proposed to predict the temperature distribution inside a fixed bed. For an actual mono-sized-sphere packed bed, the voidage lies between those of the regularly arranged beds of FCC, BCC, and SC. Through an interpolation/extrapolation process based on the pore-scale computation results of the SC, BCC, and FCC packings, the heat transfer parameters of a randomly packed bed can be calculated. To reliably estimate the local heat transfer rate, the regional mass flow rates in a packed bed are accurately predicted first. Then, the regional solid-phase thermal conduction can be independently evaluated without interference from the regional fluid-solid convection heat transfer. Additionally, a finite-thickness wall is constructed into the computational model to significantly improve the accuracy of the predicted radial temperature profiles. With realistic temperature self-adjustment within the wall, there is no need to set unrealistic boundary conditions of either isothermal, isoflux or their combinations at the outer face of the porous zone, as many conventional methods in the literature do. The solution process and necessary parameters are summarized into flowcharts. Finally, the accuracy of the new LTNE analysis process in predicting the temperature distribution throughout the packed bed is validated with the literature experiment. In contrast, the conventional methods fail to provide the correct trend of the temperature variation.

Analysis of Cavity Disk Heat Transfer by Solving Inverse Heat Transfer Problem

Abstract The flow and heat transfer within compressor rotor cavities of aero-engines is a conjugate problem. The operating conditions buoyancy forces, caused by radial temperature difference between the cold throughflow and the hotter shroud, can influence the amount of entrained air significantly. By this, the heat transfer depends on the radial temperature gradient of the cavity walls, and in turn, the disk temperatures are dependent on the heat transfer. In this article, disk Nusselt numbers are calculated in reference to the air inlet temperature and in comparison to a modeled local air temperature inside the cavity. The local disk heat flux is determined from measured steady-state surface temperatures by solving the inverse heat transfer problem in an iterative procedure. The conduction equation is solved on a 2D mesh using a validated finite element approach, and the heat flux confidence intervals are calculated with a stratified Monte Carlo approach. An estimate for the amount of air entering into the cavity is calculated by a simplified heat balance. The major influences on the Nusselt number were found to be the mass flowrate entering the cavity and the density of the fluid inside the cavity.

Performance of all-air wall induction unit for displacement ventilation in a four-bed hospital ward during the cooling period

The existing induction air-conditioning system faces ventilation shortcomings and condensation risks. We developed an all-air wall induction air terminal unit (wall IU) that doesn't require reheating and eliminates water pipes to address condensation. Moreover, with modifications to its supply method, it can achieve displacement ventilation (DV) in an adiabatic environment. However, the real-world performance of this system needs to be further confirmed. This study examines wall IU performance during the cooling period. A full-scale experiment was conducted in a room furnished as a four-bed hospital ward with an outdoor climate chamber (OCC) to simulate summer conditions. IU's cooling and ventilation performance was evaluated by examining steady-state temperatures and tracer gas distributions. Moreover, CFD simulations to reproduce the experiment were performed to supplement the results. Patients' thermal comfort and infection risk while cohabiting with an infected individual were estimated using detailed temperature, airflow, and concentration data from an experiment-based CFD analysis. Furthermore, the DV stratification height under various perimeter heat loads and performance comparison between wall and ceiling-mounted induction units were also studied. In conclusion, the wall IU improved ventilation efficiency by achieving DV under cooling supply conditions. Satisfied thermal comfort is ensured based on ADPI and DR evaluation. DV's stratification height can be kept high enough under a 20 °C equivalent temperature difference when using a single glass window or more after thermal insulation enhancement. Compared with ceiling-mounted induction units, wall-mounted units can reduce infection risk by more than double while making cold drafts less noticeable.

Exact moments and re-entrant transitions in the inertial dynamics of active Brownian particles

In this study, we investigate the behavior of free inertial active Brownian particles in the presence of thermal noise. While finding a closed-form solution for the joint distribution of positions, orientations, and velocities using the Fokker–Planck equation is generally challenging, we utilize a Laplace transform method to obtain the exact temporal evolution of all dynamical moments in arbitrary dimensions. Our expressions in d dimensions reveal that inertia significantly impacts steady-state kinetic temperature and swim pressure while leaving the late-time diffusivity unchanged. Notably, as a function of activity and inertia, the steady-state velocity distribution exhibits a remarkable re-entrant crossover from ‘passive’ Gaussian to ‘active’ non-Gaussian behaviors. We construct a corresponding ‘phase diagram’ using the exact expression of the d-dimensional kurtosis. Our analytic expressions describe steady states and offer insights into time-dependent crossovers observed in moments of velocity and displacement. Our calculations can be extended to predict up to second-order moments for run-and-tumble particles and the active Ornstein–Uhlenbeck process (AOUP). Additionally, the kurtosis shows differences from AOUP.

A theta projection model for compressive creep behaviour of refractories at high temperature: application to alumina-spinel

Thermomechanical loads are normally applied to refractory materials throughout their service life whichever is their practical use (e.g. steel ladle, rotary kiln furnaces). Among all the phenomena that the refractories are exposed to, the influence of creep behaviour is essential in determining their performance. Creep of refractories is usually represented by simple creep laws such as Norton-Bailey, which lack the capacity for generalization. The theta projection creep method, on the other hand, was proposed in the twentieth century to predict the creep of metals and alloys across different temperatures and stresses. The model is represented by one exponential equation capable of representing the complete creep curve, and coefficients that are temperature and stress-dependent, thus enabling the representation of complex nonlinear creep behaviour. Since refractories have similar creep responses to metals, the theta projection creep model is validated to characterize the compressive creep behaviour of alumina-spinel refractories at temperatures between 1200 and 1500 °C. Creep data from steady-state and transient temperature creep tests are used to calibrate the model. A regression by the least square method is applied to calculate the model’s parameters. The model shows good flexibility in fitting the test data of the alumina-spinel refractory over the three creep stages. A temperature and stress dependence model is derived for the theta coefficients, reducing the number of material parameters necessary to describe the material's behaviour. The experimental creep curves are presented, as well as the curves resulting from the identified parameters. The implications of the chosen creep data set on the definition of the model and its adequacy for this novel application are discussed.

Simultaneous estimation of SAR, thermal diffusivity, and damping using periodic power modulation for MRgFUS quality assurance

Purpose: A crucial aspect of quality assurance in thermal therapy is periodic demonstration of the heating performance of the device. Existing methods estimate the specific absorption rate (SAR) from the temperature rise after a short power pulse, which yields a biased estimate as thermal diffusion broadens the apparent SAR pattern. To obtain an unbiased estimate, we propose a robust frequency-domain method that simultaneously identifies the SAR as well as the thermal dynamics. Methods: We propose a method consisting of periodic modulation of the FUS power while recording the response with MR thermometry (MRT). This approach enables unbiased measurements of spatial Fourier coefficients that encode the thermal response. These coefficients are substituted in a generic thermal model to simultaneously estimate the SAR, diffusivity, and damping. The method was tested using a cylindrical phantom and a 3 T clinical MR-HIFU system. Three scenarios with varying modulation strategies are chosen to challenge the method. The results are compared to the well-known power pulse technique. Results: The thermal diffusivity is estimated at 0.151 mm2s–1 with a standard deviation of 0.01 mm2s–1 between six experiments. The SAR estimates are consistent between all experiments and show an excellent signal-to-noise ratio (SNR) compared to the well established power pulse method. The frequency-domain method proved to be insensitive to B 0-drift and non steady-state initial temperature distributions. Conclusion: The proposed frequency-domain estimation method shows a high SNR and provided reproducible estimates of the SAR and the corresponding thermal diffusivity. The findings suggest that frequency-domain tools can be highly effective at estimating the SAR from (biased) MRT data acquired during periodic power modulation.

Inverse Design of Axis Fan for Permanent Magnet Drive Motor for Special Vehicles

The control of mechanical energy loss is especially key in the design of permanent magnet drive motors for special vehicles. This paper takes a 300 kW high-efficiency motor as an example, and under the operating condition of 9000 rev/min, in order to control the size of the mechanical loss Pmech, improve the efficiency of the motor, as well as enhance the ventilation and heat dissipation performance of the motor, the structural parameters of the motor’s Axis fan are identified by using the Reverse Engineering (RE), and the fan performance is simulated and analysed by using the standard k-ε turbulence model of Computational Fluid Dynamics. The mechanical loss calculation model is investigated, and the effects of different blade numbers, wrap angles, and mounting angle parameters of the fan on the mechanical loss Pmech are derived. And finally, the scheme is calculated to show that when the blade number Z is 13, the wrap angle Δφ is 60°, the front mounting angle Φ1 is 45°, and the rear mounting angle Φ2 is 30°, the mechanical loss Pmech decreases from 8.0 kW to 2.54 kW, and the motor efficiency η0 is greatly improved, increasing from 94.2% to 96.1%. Meanwhile, based on finite element simulation experiments, the effects of the motor Axis fan on the steady-state temperature field of the pre-optimised and post-optimised fans are compared, and the optimised axis fan makes the motor ventilation and heat dissipation more reasonable. The maximum temperature of the motor under the same working condition decreased by 16.7 K, the efficiency η0 of this motor was greatly improved, and the efficiency η0 increased from 94.2% to 96.1%.

Enhancing overall performances of Cu/Ag/AZO multilayer films for transparent heaters via laser/furnace step-by-step annealing mode

Four different step-by-step annealing modes based on furnace and/or laser annealing (i.e. F + L, F + F, L + F and L + L) were developed and compared with one-step furnace or laser annealing mode (i.e. F and L), with an aim to enhance overall performances of Cu/Ag/AZO (CAA) multilayer films applied to transparent heaters. It was found that the L + F step-by-step annealing mode improved the transmittance and conductivity of the CAA film to the greatest extent, and therefore the resulting sample L + F achieved the best overall performance with a figure of merit of 4.26 × 10−2 Ω−1. These results should be ascribed to that laser annealing for the AZO layer in the first step facilitated growth and recrystallization of AZO grains to provide better nucleation sites for overlying Ag and Cu grains, and furnace annealing of the whole CAA film in the second step promoted the melting of the surface Ag and Cu grains to re-aggregate with the nearby AZO grains. The transparent heater prepared from the sample L + F exhibited a high steady-state temperature of 127.1 °C within a short response time of 80 s under an input voltage of 3 V, as well as good heating stability and effective deicing function.

Extension of GeN-Foam to departure from nucleate boiling prediction and validation against the OECD/NRC PSBT benchmark

The prediction of departure from nucleate boiling (DNB) has always been a crucial aspect of thermal-hydraulic codes for the analysis of Light Water Reactors. In this paper, GeN-Foam, a multi-physics code developed based on OpenFOAM, has been enhanced to incorporate DNB prediction using a CHF look-up table as well as post-CHF flow and heat transfer models. To assess GeN-Foam's accuracy in modeling DNB conditions in typical pressurized water reactors (PWRs), a preliminary validation was conducted utilizing Phase II of the PSBT benchmark, including the steady-state fluid temperature (Test Series 1), steady-state DNB (Test Series 4), and transient DNB (Test Series 11T) benchmarks. This paper presents the closure correlations implemented in GeN-Foam, provides a description of the PSBT benchmarks, and includes a comparison between GeN-Foam's predictions and experimental data, as well as code-to-code verification with other participants. The results demonstrate that GeN-Foam exhibits good performance in simulating two-phase flow boiling conditions. Furthermore, GeN-Foam accurately predicts the DNB power and time of occurrence within a ±10 % error range compared to measured values, preliminarily indicating its effectiveness in predicting DNB occurrence and two-phase flow boiling phenomena.

Mathematical Modeling of Collisional Heat Generation and Convective Heat Transfer Problem for Single Spherical Body in Oscillating Boundaries

The application of high-energy ball milling in the field of advanced materials processing, such as mechanochemical alloying and ammonia synthesis, has been gaining increasing attention beyond its traditional use in material crushing. It is important to recognize the role of thermodynamics in high-energy processes, including heat generation from collisions, as well as ongoing investigations into grinding ball behavior. This study aims to develop a mathematical model for the numerical analysis of a spherical ball in a shaker mill, taking into account its dynamics, contact mechanics, thermodynamics, and heat transfer. The complexity of the problem for mathematical modeling is reduced by limiting the motion to one-dimensional translation and representing the vibration of the vial wall in a shaker mill as rigid boundaries that move in a linear fashion. A nonlinear viscoelastic contact model is employed to construct a heat generation model. An equation of internal energy evolution is derived that incorporates a velocity-dependent heat convection model. In coupled field modeling, equations of motion for high-energy impact phenomena are derived from energy-based Hamiltonian mechanics rather than vector-based Newtonian mechanics. The numerical integration of the governing equations is performed at the system level to analyze the general heating characteristics during collisions and the effect of various operational parameters, such as the oscillation frequency and amplitude of the vial. The results of the numerical analysis provide essential performance metrics, including steady-state temperature and time constant for the characteristics of temperature evolution for a high-energy shaker milling process with a computation accuracy of 0.1%. The novelty of this modeling study is that it is the first to obtain such a high accuracy numerical solution for the temperature evolution associated with a shaker mill process.

Meteorite temperature measurements during ground testing

Ground testing meteorite samples offer in-situ measurements of known materials in conditions that occur during entry into Earth’s atmosphere. 22 meteorite samples with a wide range of origins and classifications were tested in the plasma wind tunnel facility PWK1 at the Institute of Space Systems in Stuttgart. These tests recreate the flow condition of a meteoroid during entry into earth’s atmosphere at an altitude of 78.8km altitude and a velocity of 11.7kms-1. Four optical diagnostic techniques were used to measure the surface temperature above 1000K. 2-D methods showed that the surface temperature is evenly distributed over the sample surface, while time-resolved analyses show that the samples reach a steady state temperature within 0.5s. The steady-state temperature for chondritic samples was consistent but varied significantly for achondrites and iron meteorite samples. The composition data showed a strong dependency of the surface temperature on the silicon content. The surface temperatures were shown to be dependent on the material and a database of temperatures was set up. The Planck fit methodology could be directly adapted to spectral meteor observation systems. A comparison of the method to established methods showed an offset between the methods. This data could be applied to thermal models to better understand the energy transfer processes during meteor flight.