Alternative Jet Research Articles

Numerical Study on the Operational Ventilation Patterns of Alternative Jet Fans in Curved Tunnels

In tunnel operation ventilation systems, the arrangement of jet fans plays a decisive role in ensuring ventilation efficiency. Curved tunnels, due to their unique radius of curvature, exhibit significant differences in fan installation parameters and jet flow field distribution compared to traditional straight-line tunnels. In order to investigate the distinct characteristics, this research utilized computational fluid dynamics (CFD) simulation methods to analyze the ventilation performance of both an innovative, adjustable jet fan system and conventional jet fans within the context of curved tunnel configurations. The findings reveal that by adjusting the horizontal deflection angle of the novel jet fan, the flow field distribution can be effectively optimized, and the jet effect can be enhanced, thereby improving ventilation efficiency. Compared to traditional jet fans, the novel fan demonstrates a significantly greater capability in flow field optimization, especially when its horizontal deflection angle is adjusted, showing a trend where the jet effect initially increases and then decreases, with the longitudinal impact range being adjustable within a range of 5 m to 25 m.

Simulated contrail-processed aviation soot aerosols are poor ice-nucleating particles at cirrus temperatures

Abstract. Aviation soot surrogates processed in contrails are believed to become potent ice nuclei at cirrus temperatures. This is not verified for real aviation soot, which can have vastly different physico-chemical properties. Here, we sampled soot particles from in-use commercial aircraft engines and quantified the effect of contrail processing on their ice nucleation ability at T< 228 K. We show that aviation soot becomes compacted upon contrail processing, but that does not change their ice nucleation ability in contrast to other soot types. The presence of H2SO4 condensed in soot pores, the highly fused nature of the soot primary particles and their arrangement are what limit the volume of pores generated upon contrail processing, in turn limiting sites for ice nucleation. Furthermore, we hypothesized that contrail-processed aviation soot particles emitted from alternative jet fuel would also be poor ice-nucleating particles if their emission sizes remain small (< 150 nm).

Fuzzy Rule-based Comparison of Alternative Jet Fuels

In today's aviation alternative jet fuels play an increasingly important role. Their application incurs new engineering and environmental protection challenges. The key properties of their feasibility of integration are from technological point of view aging behavior and applicability as well as from environmental protection point of view the carbon footprint. During the comparison process experts can evaluate the above characteristics with linguistic variables. The application of linguistic variables always results in some degree of uncertainty – by their subjectivities. Fuzzy calculation methods are used to mathematically describe these uncertainties. The purpose of this study as a pilot project is to gain experience in developing a methodology of a multi-level fuzzy rule-based jet fuel qualification process.

Pyrolysis mechanism of a highly branched bio-derived fuel and its blends with aviation kerosene (RP-3)

To address the environmental issues caused by traditional aviation fuels, the use of new alternative jet fuels (AJF) is emerging. C1 fuel, due to its excellent performance, is used as a blended fuel with traditional aviation kerosene. In this study, the pyrolysis pathways of C1 fuel are examined from molecular simulations. Furthermore, C1 fuel is blended with traditional aviation kerosene fuel RP-3 in a 1:4 vol ratio, and the potential coupling effects between two fuels are addressed under both pyrolysis and combustion conditions. In the process of fuel pyrolysis, it is observed that the composition of the fuel has a significant impact on the pyrolysis products. The decomposition process of C1 fuel is mainly dominated by branched-chain alkanes, while the pyrolysis of RP-3 primarily involves β-scission reactions of straight-chain alkanes. By comparing the combustion and pyrolysis processes of fuels, it is found that the combustion of fuel first involves the decomposition of fuel molecules, followed by the oxidation of pyrolysis products. Moreover, it is found that the reaction kinetics of blended fuel can be approximated using the additivity of two neat fuels, indicating a minor chemical coupling. Based on the proportion of C1 and RP-3 in the blended fuel, the mass fractions of key hydrocarbon products, including CH4, C2H2, C2H4, C2H6, C3H6, C4H6, C6H6, and C7H8, can be computed from the simulations of neat fuels. From a molecular perspective, the additivity of the HyChem model in describing the combustion behavior of blended fuels is verified.

Jet fuel production via palm oil hydrodeoxygenation over bifunctional zeolite mixture supported Ni catalyst: Effect of Si/Al ratio

The influence of the Si/Al ratio of ZSM-5 on 10 wt% Ni/ZSM-5.SAPO-11 catalysts were investigated through the palm oil hydrodeoxygenation (HDO) process, based on the product selectivity of alternative jet fuel. This study utilizes a 1 L batch reactor at 60 bar and 350 °C for palm oil hydrodeoxygenation over 10 wt% Ni/ZSM-5.SAPO-11 catalysts. Si/Al ratio of 50 produces a 10 wt% Ni/ZSM-5.SAPO-11 catalyst with the optimum physicochemical properties for palm oil hydrodeoxygenation. TGA/DTG analysis of the spent catalyst shows that the catalyst has good thermal and catalyst stability with minor carbon deposition. GC/MS analysis also demonstrated a 100 % palm oil conversion to alternative jet fuel. The highest jet fuel yield of 51 % was attained with a Si/Al ratio of 50. The physicochemical properties of alternative jet fuel samples were measured to ensure that the conventional fuel standard limits were appropriately followed. These results indicated that such types of bifunctional Ni-based catalysts have the potential to be used in the conversion of triglycerides to alternative jet fuel.

Indications of Endocrine Disruptor Effects of JP-5 Jet Fuel Using a Rat-Model Reproductive Study and an In Vitro Human Hormone Receptor Assay.

Recent events concerning jet fuel contamination of drinking water have shown that we need a better understanding of the effects of ingested jet fuel. To this end, a reproductive study with ingested jet fuel in rats was undertaken with relatively high concentrations of Jet Propellant (JP)-5 along with a human estrogen receptor activation in vitro assay using JP-5, JP-8, and an alternative jet fuel derived from the camelina plant referred to as HydroRenewable Jet (HRJ) fuel, to help evaluate potential effects of ingested jet fuel. The results of the in vivo study provide evidence that JP-5 can act as an endocrine disruptor, with specific observations including altered hormone levels with JP-5 exposure (significantly lower estradiol levels in male rats and significantly increased Dehydroepiandrosterone levels in females), and a decreased male/female offspring ratio. The in vitro hormone receptor activation assay indicated that JP-5 and JP-8 are capable of upregulating human estrogen receptor (ER) activity, while HRJ was not active in the ER assay. The jet fuels were not able to activate androgen or glucocorticoid receptors in further in vitro assays. These results infer potential endocrine disruption associated with JP-5, with activation of the estrogen receptor as one potential mechanism of action.

PLIF Flame Study on the Qualitative and Quantitative Measurement of OH Species for Conventional and Alternative Jet Fuels; Experimental and Theoretical Investigations

ABSTRACT The hydroxyl molecule is one of the most important intermediate species in the chemistry of combustion processes and plays an important role in the chemical reactions of a hydrocarbon-air flame. However, investigation on a laser-based quantitative measurement of OH in heavy liquid hydrocarbon flames remains very scarce. Thus, in this study, OH radicals were measured qualitatively with the aid of planar laser-induced fluorescence in atmospheric pressure studies of burner stabilized laminar flames of kerosene and alcohol-to-jet (ATJ) fuel. These qualitative profiles were then put on a quantitative basis by analysis of the impact of temperature on the Boltzmann distribution of OH over the ground electronic state rotational energy levels and the use of a simple methane reference flame and its modeling using ANSYS Chemkin-Pro. The quantitative profiles in turn were used to validate the developed chemical kinetic mechanisms of kerosene and ATJ combustion. An experimental apparatus has been developed to investigate the temperature profile and the OH relative amounts of kerosene and ATJ laminar flames in an optimized premixed flat flame burner, under three different air/fuel ratio conditions. Fine wire type thermocouples were applied to provide reliable temperature profiles for the fuel flames. In general, reasonable agreement were observed between the experimental OH results and the simulations for the target fuel flames in the case of kerosene, while a higher peak value of OH was predicted in the ATJ model output compared to the PLIF derived data.

Kinematic viscosity prediction of jet fuels and alternative blending components via comprehensive two-dimensional gas chromatography, partial least squares, and Yeo-Johnson transformation.

This work presents an accurate yet simplified partial least squares model to predict the kinematic viscosity of conventional and alternative jet fuels at -20°C using comprehensive two-dimensional gas chromatography coupled to a flame ionization detector (GC×GC/FID). Three different normalization methods (mean-centering, logarithmic, and Yeo-Johnson) were evaluated to identify their impact in the prediction of middle distillates' physical properties. Results using Yeo-Johnson transformation exhibited improved viscosity prediction capabilities over the validation set with a mean absolute percentage error of 5.3%, a root-mean-squared error of 0.23, and a coefficient of determination (R2 ) of 0.9404 using only 10 latent variables. Unlike previously reported correlations, this model allowed the identification of specific hydrocarbon groups and carbon numbers that drive jet fuel viscosity at low temperatures. The presence of even small amounts of large branched-alkanes (C15 -C17 ), dicyclic-alkanes (C10 ), and cycloaromatics (C11 ) have the potential to strongly increase the kinematic viscosity of jet fuels. Contrastingly, light monocycloalkanes and branched-alkanes (≤ C10 ) were associated with lower viscosity values. Novelly, this model suggests the implementation of Yeo-Johnson transformations to predict the physical properties of middle distillates to further improve the performance metrics of partial least squares models based on GC data.

Prospects for Low-Resolution NDIR Sensors to Discern Ignition Properties of Fuels

Abstract The cetane number (CN) is an important fuel property to consider for compression ignition engines as it is a measure of a fuel's ignition delay. Derived cetane number (DCN) already varies significantly within jet fuels. With the expected increasing prevalence of alternative jet fuels, additional variability is expected. DCN is usually assigned to fuels using ASTM methods that use large equipment like the ignition quality tester (IQT), which consumes a lot of fuel and is cumbersome to operate. Over the last decade, there have been advances in the development of chemometric models, which use machine learning to correlate infrared spectra of fuels to fuel properties like DCN, density, and C/H ratio, among many others. These techniques have certain advantages over the ASTM methods, and previous studies performed on samples of diesel fuels have shown high accuracies in DCN prediction. However, this accuracy is generally a result of high resolution, making the equipment expensive, relatively large for handheld sensors, and power-hungry. On the other hand, nondispersive infrared (NDIR) sensors, despite having a low resolution, are attractive because they can be compact, inexpensive, and power efficient. These characteristics are important for handheld or onboard fuel sensors. However, one would anticipate a tradeoff between these advantages and accuracy. This study investigates this tradeoff and the feasibility of low-resolution NDIR sensors to discern fuel properties such as DCN by using Machine Learning models trained on real FTIR data, and DCNs obtained from IQT. DCN predictions were made for blends of ATJ/F-24, CN fuels, and neat Jet A1, A2, and JP 5, with an error limit of 10%. It was found that there seems to be sufficient variability in the near infrared (NIR) range to discern DCN with a feasible number of channels, but the channels have to be narrow (e.g., FWHMs as narrow as 60 nm). For the dataset in the study, the performance of linear models was better than the nonlinear model. Finally, NIR region beyond 1050 nm was found to be more important in DCN prediction, primarily the regions consisting of the first and second C-H overtones and the C-H combination band.

A neural network potential energy surface assisted molecular dynamics study on the pyrolysis behavior of two spiro-hydrocarbons.

Spiro-hydrocarbons are potentially a type of novel alternative jet fuel due to their high density and net heat of combustion. In this work, the pyrolysis study of two spiro-hydrocarbons (spiro[cyclopropane-1,6'-tricyclo[3.2.1.02,4]octane] (C10H14) as Fuel 1 and spiro[bicyclo[2.2.1]heptane-2,1'-cyclopropane] (C9H14) as Fuel 2) is performed via molecular dynamics (MD) simulations, with a neural network potential energy surface (NNPES), deep potential (DP) model, adopted. The data set for the DP model of each fuel is constructed after 31 and 27 iterations, respectively. The high precision of the DP model is demonstrated, and the temperature transferability of each model is observed. The overall pyrolysis performance is evaluated with the fuel decomposition rate, showing that both fuels have comparable gas-reactivity to commercial aviation fuels, such as JP-10. The reaction networks of initial pyrolysis for Fuels 1 and 2 are constructed, and the contribution of each pathway is discussed. Fuel 1 tends to form an unsaturated six-membered ring structure, while Fuel 2 generates unsaturated open-chain hydrocarbons. Further analyses of the MD results provide time-evolution information on each component in the pyrolysis species pool. Compared to Fuel 1, the initial pyrolysis of Fuel 2 leads to more hydrogen, alkenes, and alkanes, as well as fewer monocyclic aromatic hydrocarbons (MAHs), demonstrating a reduced tendency for afterward coking. This work might contribute to the development of the mechanism of the two spiro-hydrocarbons and guide the research of other similar structural fuels.

Methodologies for alternative jet fuels testing on small-scale reaction engines

Methodologies for alternative jet fuels testing on small-scale reaction engines

Numerical Modeling of Chemical Kinetics, Spray Dynamics, and Turbulent Combustion towards Sustainable Aviation

With growing interest in sustainable civil supersonic and hypersonic aviation, there is a need to model the combustion of alternative, sustainable jet fuels. This work presents numerical simulations of several related phenomena, including laminar flames, ignition, and spray flames. Two conventional jet fuels, Jet A and JP-5, and two alternative jet fuels, C1 and C5, are targeted. The laminar burning velocities of these fuels are predicted using skeletal and detailed reaction mechanisms. The ignition delay times are predicted in the context of dual-mode ramjet engines. Large Eddy Simulations (LES) of spray combustion in an aeroengine are carried out to investigate how the different thermodynamic and chemical properties of alternative fuels lead to different emergent behavior. A novel set of thermodynamic correlations are developed for the spray model. The laminar burning velocity predictions are normalized by heat of combustion to reveal a more distinct fuel trend, with C1 burning slowest and C5 fastest. The ignition results highlight the contributions of the Negative Temperature Coefficient (NTC) effect, equivalence ratio, and hydrogen enrichment in determining ignition time scales in dual-mode ramjet engines. The spray results reveal that the volatile alternative jet fuels have short penetration depths and that the flame of the most chemically divergent fuel (C1) stabilizes relatively close to the spray.

Influence of fuel characteristics on the alternative jet fuel atomization at non-reacting conditions

Synthetic paraffinic kerosene jet fuel derived from natural gas (NG-SPK) is gaining importance as a low-emission alternative fuel for aviation combustors. In this context, the influence of fuel properties on the atomization of NG-SPK jet fuel at non-reacting, evaporating conditions is investigated. The spray results of NG-SPK jet fuel are compared with the reference, Jet A-1 fuel. This study considers a simplex atomizer, commonly deployed as a pilot injector in aviation gas turbine combustors for ignition at sea level and in high-altitude relight conditions. The local atomization characteristics like droplet concentration, mean diameters, and mean axial droplet velocity is obtained experimentally using phase Doppler anemometry technique at different ambient gas pressures of 100, 500, and 900 kPa while maintaining the ambient temperature at 400 K. The fuel dispersion parameters are measured at two nozzle pressure differentials of 300 and 900 kPa. The NG-SPK jet fuel exhibited higher droplet concentrations for the conditions studied than conventional fuel. Furthermore, the droplet size distribution of NG-SPK jet fuel revealed a higher percentage of smaller droplet diameters than Jet A-1 fuel. This difference in droplet characteristics can positively influence the heat release patterns under reacting conditions.

Formulation of a Jet Fuel Surrogate and Its Kinetic Chemical Mechanism by Emulating Physical and Chemical Properties of Real Jet Fuel

The application of jet fuel in gas turbines and diesel engines adheres to the Army’s single-fuel forward policy, streamlining supply chains. To ensure precise engine combustion numerical studies, surrogate fuels and mechanisms should faithfully replicate real fuel properties and combustion traits. In this work, a new four-component jet fuel surrogate containing 39.05% n-dodecane/21.79% isocetane/11.49% decalin/27.67% toluene by mole fraction is formulated based on a property optimizer. The new-formulated fuel surrogate can satisfactorily emulate the chemical and physical properties of real jet fuel, including cetane number (CN), threshold sooting index (TSI), molecular weight (MW), lower heating value (LHV), the ratio of hydrogen and carbon (H/C), liquid density, viscosity, and surface tension. Furthermore, a reduced and robust kinetic chemical mechanism (containing 124 species and 590 reactions) that could be directly employed in practical engine combustion simulations has also been developed for the proposed surrogate jet fuel. The mechanism is validated through comprehensive experimental data, including ignition delay time (IDT) determined in shock tubes and rapid compression machines (RCMs), species mole fractions measured in premixed flames and jet stirred reactors (JSRs), and laminar flame speeds. Generally, the property deviations of the jet fuel surrogate are less than 2% except for MW (10.73%), viscosity (5.88%), and surface tension (8.71%). The comparison results between the predictions and measurements are in good agreement, indicating that the current kinetic mechanism is capable of reflecting the oxidation process of real jet fuel. The current mechanism can accurately capture variations in the ignition delay time in the negative temperature coefficient (NTC) region as well. In the future, the proposed surrogate jet fuel could be applied in practical engine computational fluid dynamic (CFD) simulations.

Experimental study of droplet vaporization for conventional and renewable transportation fuels: Effects of physical properties and chemical composition

As part of the global energy transition, an increasing number of sustainable liquid fuels with a wide range of physical and chemical properties becomes available for gas turbine and IC engines. For an optimal design and operation of these engines, an improved understanding of the effects of fuel properties on atomization, vaporization and combustion kinetics is required. The present work provides a comprehensive experimental study of fuel effects on droplet vaporization for numerous conventional and alternative fuels. The study employs a recently developed flow channel, where free-falling droplets with initial diameters of D≈77μm vaporize under technically relevant gas temperatures Tg of up to 1300 K. The evolution of droplet diameters over travel distance and time is measured using microscopic shadow imaging. A total of 13 single fuel components, five bi- and tri-component mixtures, six conventional and alternative jet fuels and mixtures thereof, and three IC engine fuels and mixtures thereof have been tested under well-reproducible ambient conditions. The fuels represent a wide range of chemical classes such as n-alkanes, iso-alkanes, cycloalkanes, aromatics, alcohols and oxymethylene ethers, and most of them were measured for the first time with realistic D and Tg. The results for the single fuel components reveal in detail the temperature-dependent effects of physical properties such as boiling point Tb, liquid density ρl and enthalpy of vaporization Hv. In particular, it was found that for high gas temperatures of about 1250 K, the vaporization rate is almost completely determined by the product of Hv and ρl. By comparison with the results for single n-alkanes, the measurements for bi- and tri-component mixtures accurately characterize the preferential vaporization of individual fuel components over droplet lifetime. The results for various multi-component fuels reveal complex interplays of preferential vaporization and temperature-dependent influences of physical properties. It is shown that the vaporization for conventional and corresponding alternative fuels can differ significantly. Finally, the droplet vaporization is characterized for mixtures of PRF90+ethanol and ethanol+water, which exhibit a non-ideal vapor–liquid equilibrium.

Liquid Hydrogen: A Mirage or Potent Solution for Aviation's Climate Woes?

The aviation industry faces a formidable challenge to cap its climate impact in the face of continued growth in passengers and freight. Liquid hydrogen (LH2) is one of the alternative jet fuels under consideration as it does not produce carbon dioxide upon combustion. We conducted a well-to-wake life cycle assessment of CO2 emissions and non-CO2 climate change impacts per passenger-distance for 17 different hydrogen production routes, as well as conventional jet fuel and biofuels. Six other environmental and health impact categories were also considered. The Boeing 787-800 was used as the reference aircraft, and a range of flight distances were explored. Contrail cirrus contributes around 81 ± 31% of the combustion climate impacts for LH2, compared to 32 ± 7% for conventional jet fuel, showing that research is needed to reduce uncertainty in the case of LH2. The life cycle impacts of the two dominant commercial LH2 pathways are on average 8 and 121% larger than conventional jet fuel. Some novel LH2 pathways do show considerable potential for life cycle climate impact reductions versus conventional fuel (up to -205 ± 78%). LH2 from renewable energy is not climate neutral, though, at best -67 ± 10% compared to conventional over the life cycle.

Coupling effect of vehicle wake and jet flow on the dispersion characteristics and dilution efficiency of pollutants in urban highway tunnels

The pollutants emitted by traveling vehicles are prone to accumulation inside urban highway tunnels, which poses a serious threat to the driving safety and health of passengers. This study employed the dynamic mesh method to simulate a traveling vehicle and investigated the coupling effect of vehicle wake and jet flow on the dispersion characteristics of pollutants in urban highway tunnels. To ensure the accuracy of the numerical simulation results, the turbulence model (realizable k–ε model) and dynamic mesh model were validated through field tests. The results revealed that jet flow can disrupt the large-scale longitudinal vortices pattern in the wake region, whereas vehicle wake can simultaneously weaken the entrainment strength of jet flow. The jet flow was found to be decisive in the space with a height greater than 4 m, whereas the vehicle wake intensity was considerably stronger at the bottom space of the tunnel, leading to the accumulation of pollutants in the passenger breathing zone. To evaluate the effect of jet fans on pollutants in the breathing zone, an innovative dilution efficiency was proposed. The dilution efficiency can be significantly affected by the intensity of vehicle wake and turbulence. Moreover, the dilution efficiency of alternative jet fans was better than that of traditional jet fans.

Spray characteristics of natural gas-based alternative jet fuel at high pressure ambient conditions

Alternative fuel like Gas-To-Liquid (GTL) jet fuel derived from natural gas is gaining importance in aviation industry due to their cleaner-burning nature. In this context, this study focuses on the role of ambient conditions on the atomization characteristics of GTL jet fuel at inert conditions, and the outcomes are compared with those of the reference, Jet A-1 fuel. For this purpose, a simplex atomizer, commonly utilized as a pilot-injector in aviation combustors for ignition at sea-level and in high-altitude relight conditions, is considered. The local atomization characteristics like droplet concentration, mean diameter and droplet mean axial velocity are obtained experimentally by employing the phase Doppler anemometry technique at different conditions (ambient gas pressures of 100, 500, and 900 kPa, and ambient temperature at 400 K). The fuel dispersion parameters are measured at different locations far from the atomizer while maintaining the pressure differentials across the atomizer at 300 and 900 kPa. For the conditions studied, the dispersion features are greatly influenced by the ambient conditions. At higher ambient gas pressures, GTL jet fuel exhibited higher droplet concentrations than conventional fuel, and smaller droplet and Sauter mean diameters. This difference in droplet characteristics can positively influence the energy release patterns of GTL jet fuel in a combustion environment.

 MODELLING AND SIMULATION OF THE COMBUSTION OF BIODERIVED FUELS IN A PT6A-27 TURBOPROP ENGINE

The motivation for venturing in alternative jet fuels has partly been due to the elevated level and volatility of the price of Jet A and environmental impacts on global climate change and air quality. The model of the annular combustor for the PT6A-27 engine was created using SOLIDWORKS and exported to ANSYS DESIGN MODELER. Creation of the computational mesh for the geometry using ANSYS MESHING was done in preparation for the setting up of the CFD simulation in ANSYS FLUENT. The simulation included, setting material properties and boundary conditions for a non-premixed combustion problem. Initiating the calculation with residual plotting, calculating the solution using the pressure-based solver and visually examining the flow and temperature fields using the post-processing in ANSYS FLUENT with the Standard k-ε 2 equation turbulence model used. The fuel blend from the range of 30% bioethanol and 70% biodiesel (BE30-BD70) to 70% bioethanol and 30% biodiesel (BE70-BD30) indicated a combustion characteristic consistency with that obtained from the combustion of Jet-A1. Further, from the comparisons of the blends in terms of performance and single biofuel combustion simulation the best blend combination was 40% bioethanol with 60% biodiesel (BE40-BD60) whose adiabatic flame temperature was about 2260 Kelvins. The blend of 40% bioethanol to 60% biodiesel was observed to have a reduced Fuel NOx footprint and the observed production rate values of Thermal NOx were a range of to Whereas a pure JetA-1 hydrocarbon fuel had a production rate of Thermal NOx ranging from to . This was indicative of a reduction in Thermal NOx when the two groups of fuels (Jet-A against 40BE & 60BD blend) were compared. These results showed that reduction of NOx emissions is achievable for a blend of 40% bioethanol and 60% biodiesel in a combustion reaction as a substitute for the hydrocarbon JetA-1 in the PT6A-27 turboprop engine. KEY WORDS—PT6A-27, nonpremixed Combustion, NOx, Turbulence model

Evaluating generative models in high energy physics

There has been a recent explosion in research into machine-learning-based generative modeling to tackle computational challenges for simulations in high energy physics (HEP). In order to use such alternative simulators in practice, we need well-defined metrics to compare different generative models and evaluate their discrepancy from the true distributions. We present the first systematic review and investigation into evaluation metrics and their sensitivity to failure modes of generative models, using the framework of two-sample goodness-of-fit testing, and their relevance and viability for HEP. Inspired by previous work in both physics and computer vision, we propose two new metrics, the Fr\'echet and kernel physics distances (FPD and KPD, respectively), and perform a variety of experiments measuring their performance on simple Gaussian-distributed, and simulated high energy jet datasets. We find FPD, in particular, to be the most sensitive metric to all alternative jet distributions tested and recommend its adoption, along with the KPD and Wasserstein distances between individual feature distributions, for evaluating generative models in HEP. We finally demonstrate the efficacy of these proposed metrics in evaluating and comparing a novel attention-based generative adversarial particle transformer to the state-of-the-art message-passing generative adversarial network jet simulation model. The code for our proposed metrics is provided in the open source JetNet Python library.