Hasil untuk "Oils, fats, and waxes"

Xiaoming Wang, Junbin Chen, Hao Wang et al.

Abstract The development of natural fractures can easily lead to horizontal wellbore instability caused by stress concentration after drilling in shale reservoirs, which is not conducive to the safe development of shale gas, but how different natural fractures impact the horizontal wellbore stability in shale reservoirs is still unclear. Therefore, the effect of single straight, intersecting, and T-shaped natural fractures on horizontal wellbore stability in shale reservoirs is studied. Then a stress distribution model around the horizontal wellbore in shale reservoirs considering natural fractures is established based on linear elasticity theory, the stress distribution around horizontal wellbores in shale reservoirs with single straight, intersecting, and T-shaped natural fractures is acquired through the finite element method (FEM), and the effect of different natural fractures on horizontal wellbore stability is analyzed finally. Results show that among three types of natural fractures, intersecting natural fractures relieve the maximum stress of 1.676 × 106Pa, and the horizontal wellbore is the most stable; T-shaped natural fractures have the largest effect on total stress around the horizontal wellbore, which is the largest and can reach 68.105 × 106Pa, which makes the wellbore the most unstable; single straight natural fractures and intersecting natural fractures can cause the maximum circumferential stress on the wellbore wall respectively in the two directions of the maximum horizontal principal stress and the vertical principal stress, and wellbore wall is prone to compression and tensile failure respectively; circumferential stress and total stress around horizontal wellbore are the largest in the direction of the maximum horizontal principal stress, the wellbore is the most unstable. This work will be helpful for a more reliable assessment of borehole instability and benefit the drilling design in shale reservoirs with single straight, intersecting, and T-shaped natural fractures.

Sergey Matveenko, Nikita Rastegaev

In this paper we discuss a one-dimensional model for two-phase Enhanced Oil Recovery (EOR) floods, primarily for the polymer flood. We improve upon the method for the construction of semi-analytical solutions for the oil displacement by a water slug containing dissolved chemicals given in (Pires, Bedrikovetsky and Shapiro, 2006) and later generalized in (Apolinário, de Paula and Pires, 2020), (Apolinário and Pires, 2021). This method utilizes a transformation into the Lagrange coordinates that splits the equations and allows one to solve the chromatographic one-phase problem separately. The solution is then substituted into a scalar hyperbolic conservation law, which is solved using the method of characteristics. However, there is often a gap in the characteristics near the chemical shock front. It was posited to the authors that the Jouguet principle could be used to close that gap. However, no rigorous justification was given for this approach, and as such it remained a heuristic. We analyze the conditions for the appearance of the gap and its properties, and give a proper argumentation for the Jouguet heuristic and its applicability based on the Kružkov-type uniqueness theorem for the conservation law system. Additionally, a second splitting technique within the Lagrange coordinates is developed that simplifies this analysis and the construction of characteristics. Keywords: Enhanced oil recovery, Polymer flooding, Slug injection, Conservation laws, Hyperbolic systems of partial differential equations

Zhu Jinsong, Song Xiaojian, Yu Yanfei et al.

During the operation of the rotary steering system， the magnetic interference faced by the steering head when performing dynamic measurement tasks mainly comes from two aspects： one is the magnetic influence of the internal current fluctuation of the M30 bus， and the other is the external magnetic interference in the real-time environment of the drilling operation. Specifically， when the current intensity of the M30 bus is greater than 1 A， an interference magnetic field will be generated， which directly challenges the magnetic measurement accuracy of the steering head. Meanwhile， the elements such as bit and mud flow involved in drilling further aggravate the degree of magnetic interference， which not only significantly reduces the magnetic measurement accuracy of the steering head， but also may mislead the judgment of the azimuth gamma and resistivity imaging areas， leading to engineering errors. To address the above problems， a magnetic interference correction scheme for the steering head was innovatively proposed. First， magnetic interference regression analysis was conducted on the current of the M30 bus. Then， by means of integrating attitude measurement principles with multi-point analysis techniques， the single-point correction and the multi-point correction model optimized by an adaptive genetic algorithm were creatively applied to conduct deep and precise calibration on the three-axis fluxgate sensor. Analysis on the data obtained after application in DengX well shows that this method reduces the dynamic magnetic measurement azimuth angle error of the rotary steering system by 85%. Further application in multiple well clusters in Huabei Oilfield and Changqing Oilfield shows that the azimuth angle consistency of static magnetic measurement is improved by 13%. These application practices prove the effectiveness of the magnetic interference correction method in significantly improving the dynamic magnetic measurement accuracy of rotary steering.

Jianhua Guo, Yong Ma, Yatian Li et al.

Abstract Luzhou, in the southern Sichuan Basin, is one of China’s major shale-gas production areas; however, its extensive Permian carbonate formations frequently exhibit gas-logging anomalies and minor gas intrusion during drilling—both in carbonate and shale strata—severely impairing drilling efficiency. In this study, a two-pronged modeling strategy is introduced. First, based on porous–elastic coupling theory, a pore-pressure prediction model for carbonate and shale formations is established, subdividing the reservoir into high- and low-pressure zones to enhance precision. Second, the conventional Eaton model is applied across the full well section. Model performance is assessed against measured pressure data from the B and C wells. In the carbonate interval, the porous–elastic model achieved an average error of 6.02%, compared with 39.06% for the Eaton model. In the shale interval, the two approaches produced comparable errors of 8.75% for the fluid–solid coupling method and 3.30% for the Eaton method. The novel incorporation of stress-dependent zonal partitioning into the porous-elastic framework represents a significant advance beyond single-model approaches reported in previous literature. These findings demonstrate that the coupled model markedly improves pressure estimates in carbonate strata, while the Eaton model remains appropriate for shale. This hybrid methodology offers robust, quantitative support for guiding drilling design and risk mitigation in complex geological settings.

李亚1，罗兰1，田云才2,3，董俊姿4，田勇2,3， 李冰4，张文环2,3，吴明一1 LI Ya1, LUO Lan1, TIAN Yuncai2,3, DONG Junzi4, TIAN Yong2,3, LI Bing4, ZHANG Wenhuan2,3, WU Mingyi1

旨在为栀子的进一步开发和利用提供参考数据，使用正己烷索氏提取法和乙醇提取法提取产自湖南宁乡、江西九江、江西抚州、福建福鼎、江西金溪和江西樟树的6种栀子籽中的油脂，并对其理化性质、脂肪酸组成、功能成分（西红花苷Ⅰ、磷脂、 β-谷甾醇）含量及活性（DPPH自由基清除能力、紫外吸收能力）进行比较。结果表明：正己烷索氏提取法的栀子油得率高于乙醇提取法的；以正己烷索氏提取法提取栀子油，福建福鼎的栀子油得率最高，为（15.41±0.21）%，且其碘值和皂化值(KOH)最高，分别为(89.87±5.25) g/100 g和(164.96±8.24) mg/g，江西樟树的栀子油酸值（KOH）最低，为（2.35±0.09）mg/g，而江西抚州的栀子油过氧化值最低，为（0.14±0.01）g/100 g；正己烷索氏提取法提取的栀子油中，江西金溪的西红花苷Ⅰ含量最高（0.46 mg/g），江西九江的β-谷甾醇含量最高（0.99 mg/g），江西樟树的磷脂含量最高（11.75 mg/g）；正己烷索氏提取法和乙醇法提取的栀子油中，主要含有油酸和亚油酸2种不饱和脂肪酸，总含量在80%~85%之间；正己烷索氏法提取的江西金溪栀子油的DPPH自由基清除能力最强，而乙醇法提取的福建福鼎栀子油的紫外吸收能力最高。综上，不同产地栀子油的理化性质、功能成分含量及活性差别较大。In order to provide reference data for the further development and utilization of Gardenia jasminoides Ellis, different solvents (n-hexane and alcohol) were used to extract six kinds of oil from Gardenia jasminoides Ellis seeds collected from Ningxiang of Hunan Province, Jiujiang of Jiangxi Province, Fuzhou of Jiangxi Province, Fuding of Fujian Province, Jinxi of Jiangxi Province and Zhangshu of Jiangxi Province, respectively. The physicochemical properties, fatty acid composition, functional components (crocin-I, phospholipid,β-sitosterol), and activities (DPPH free radical scavenging capacity, UV absorption capacity) of the oils extracted were compared and analyzed. The results showed that the yield of Gardenia jasminoides Ellis seed oil extraced by n-hexane Soxhlet method was higher than that by alcohol extraction method. For extraction of Gardenia jasminoides Ellis by n-hexane Soxhlet method, the highest oil yield of (15.41±0.21)% was from Fuding, with the highest iodine value and saponification value at (89.87±5.25) g/100 g and (164.96±8.24) mgKOH/g, respectively. For the Gardenia jasminoides Ellis seed oil extracted with n-hexane Soxhlet method, the oil from Zhangshu had the lowest acid value of (2.35±0.09) mgKOH/g, the oil from Fuzhou had the lowest peroxide value of (0.14±0.01) g/100 g, the oil from Jinxi had the highest crocin-I content of 0.46 mg/g, the oil from Jiujiang had the highest β-sitosterol content of 0.99 mg/g, and the oil from Zhangshu had the highest phospholipid content of 11.75 mg/g. The Gardenia jasminoides Ellis seed oils extracted by both the n-hexane Soxhlet method and the alcohol method mainly contained two unsaturated fatty acids of oleic acid and linoleic acid with total contents ranging from 80% to 85%. Additionally, the Gardenia jasminoides Ellis seed oil extracted by n-hexane from Jinxi had the strongest DPPH free radical scavenging capacity, and Gardenia jasminoides Ellis seed oil extracted by ethanol from Fuding had highest UV absorption capacity. In conclusion, the physicochemical properties, functional components and activity of Gardenia jasminoides Ellis seed oil from different origins are various.

徐影影1,2，苗永军3，赵文革4，杜建4，郑畅1，刘昌盛1，陈洪建5，邓乾春1 XU Yingying1,2 , MIAO Yongjun3, ZHAO Wenge4, DU Jian4, ZHENG Chang1, LIU Changsheng1, CHEN Hongjian5, DENG Qianchun1

核桃油营养丰富，富含不饱和脂肪酸及多种对人体有益的微量营养物质，但其稳定性差，在加工时易氧化酸败，极大地影响了核桃油产品的品质与安全，制约了核桃油产业的发展。为了改善核桃油品质，延长其货架期，重点综述了近年来有关核桃油加工技术对其氧化稳定性的影响和核桃油抗氧化技术的研究进展。核桃油加工技术主要包括前处理、提取和精炼，适宜的加工工艺有利于提高核桃油品质、保留微量营养成分及提高氧化稳定性。在抗氧化方面，可以采用添加抗氧化剂、制备调和油、将其制成微胶囊和油凝胶等延缓核桃油的氧化酸败。未来仍需探索合适的核桃油加工及抗氧化技术，以延长其货架期。Walnut oil is rich in nutrients, containing unsaturated fatty acids and a variety of beneficial trace nutrients for the human body. However, walnut oil has poor stability and is prone to oxidative rancidity during processing, which greatly affects the quality and safety of walnut oil products and constrains the development of the walnut oil industry. To improve the quality of walnut oil and extend its shelf life,the research progress in recent years on the impact of walnut oil processing technologies on its oxidative stability and the development of antioxidant technologies for walnut oil were reviewed. Walnut oil processing technologies mainly include pretreatment, extraction and refining. Appropriate processing technologies are beneficial for enhancing the quality of walnut oil, retaining trace nutrients, and improving oxidative stability. In terms of antioxidation, methods such as adding antioxidants, preparing blended oils, and forming microcapsules and oleogels can be used to delay the oxidative rancidity of walnut oil.There is still a need to explore suitable processing and antioxidant technologies to extend the shelf life of walnut oil in the future.

XU DAN, ZHANG CONG, JIA HUIMIN et al.

Helium is a crucial strategic resource with very limited reserves, but its enrichment and dilution mechanisms in gas reservoirs remain unclear. Noble gas isotopes play an important role in characterizing the interactions between gas and groundwater. In this study, noble gas compositions and isotopic signatures of coalbed methane (CBM) from the third coal seam in the southern Qinshui Basin were analyzed to determine the isotope composition characteristics of noble gas and to establish a helium reservoir formation model. Gas samples were collected from 13 CBM production wells. The results showed that the helium (He) content in CBM was generally one order of magnitude higher than in the atmosphere. The ³He/⁴He ratios were 0.002 9-0.021 8 <italic>R</italic>_a, with a very low mantle source contribution (0-0.31%). The ²⁰Ne/²²Ne ratios (10.09-10.43) and ²¹Ne/²²Ne ratios (0.029 6-0.031 9) were slightly higher than those in the atmosphere, reflecting an excess of ²¹Ne relative to the atmosphere. The ⁴⁰Ar/³⁶Ar ratios (295.23-779.44) were overall higher than the atmospheric values, suggesting a significant influence of crustal ⁴⁰Ar accumulation over time. The isotopic signatures of krypton (Kr) and xenon (Xe) were similar to those of the atmosphere. Quantitative calculations of helium production revealed an external ⁴He flux into the self-generating and self-preserving CBM system. The linear relationship between ⁴He and ²⁰Ne indicated that helium dissolved in groundwater before degassing into the gas reservoir, while methane desorbed from coal seams diluted helium (as well as neon and argon) in the groundwater-associated gases. Therefore, gas reservoirs with lower grades were more likely to accumulate helium. Helium was mainly distributed in areas with effective helium source rocks, ancient groundwater systems, efficient migration channels, and appropriate hydrocarbon generation intensity, providing a theoretical basis for exploring helium resources in CBM. Rayleigh fractionation, dilution modelling, and gas production quantification showed that the water output per well during gas production was 8.03×10³-1.63×10⁶ m³. CBM exploration affected only the local water around each well, offering a basis for optimizing well spacing design.

Pinar Ankaraligil, Buket Aydeniz-Guneser

Oleogelation has proven to be a successful strategy for structuring oils. In recent years, the use of oleogels as a deep frying medium has gained popularity as an effective approach to minimise oil uptake and reduce the energy content of fried foods. This study was designed to evaluate an oleogel matrix consisting of rice bran wax and canola oil, prepared by oleogelation technique, as a deep frying medium. Two types of the oleogels (CRBO-3 with 3 g wax/100 g oil; CRBO-6 with 6 g wax/100 g oil) were formulated and these oleogels were tested as a frying medium for fish fillets. The prepared oleogels were compared with refined canola oil (CO, control) and evaluated for both the frying stability of the oils and the volatile profile of the fried fish fillets. In particular, differences were observed in the crystallization and melting profiles of oleogels before and after frying. Lower levels of total polar material, peroxide value and trans fatty acids contents were noticed in fish fillets fried in the oleogels. An increase in wax concentration had an impact on the volatile profile of fish fillets and lead significant increases in p-xylene, pentene-3-ol and nonanoic acid. In general, oleogel-based frying medium contributed to the formation of characteristic fish fillet including aroma notes of pineapple, balsamic and honey when compared to fish fried in refined canola oil. The findings suggest oleogels as an alternative frying medium for fish with reduced calorie value and improved aromatic quality. Oleogelation has a positive impact on the production of fried foods or snacks with lower fat and calorie content. Oleogelation, which is considered a healthy strategy for structuring oils to a solid consistency, will promote the repeated use of frying oils. The volatile aroma profile of fish fried in rice bran wax-canola oil oleogels as a frying medium is reported for the first time in the literature. Oleogelation has a positive impact on the production of fried foods or snacks with lower fat and calorie content. Oleogelation, which is considered a healthy strategy for structuring oils to a solid consistency, will promote the repeated use of frying oils. The volatile aroma profile of fish fried in rice bran wax-canola oil oleogels as a frying medium is reported for the first time in the literature.

Yanping Liu, Wei Zhou, Hongxia Gao et al.

D‐limonene is an important flavouring ingredient with a wide range of applications. However, its high volatility and low stability have severely impacted its application in the food industry. To address these limitations, temperature‐flavour release control system is expected to be established to reduce the loss of D‐limonene during processing and storage, as well as to control its release by temperature. The aim of the current study is to construct an oleogel system to encapsulate D‐limonene using carnauba wax as a gelling agent and palm oils (POs) as the base oil. POs with 24 °C, 38 °C, 42 °C, 48 °C, and 52 °C melting points were selected to systematically investigate the effects of the base oil melting point on the crystal morphology, interactions, physicochemical properties, microstructure, and D‐limonene release of the oleogels. The enthalpy of melting, enthalpy of crystallisation, hardness, stickiness, and gel strength increased in oleogels prepared using POs with a higher melting point. In addition, the oil‐binding capacity (OBC) (>95%) of the oleogels increased with the base oil melting point, while the fat crystal distribution became more homogeneous and denser. Based on the influence that extraction temperature has on the concentration of released D‐limonene (a lower concentration of aroma was released from high‐melting‐point POs oleogels at low temperatures (2.5 mg mL−1), suitable POs can be selected to achieve the release or retention of the aroma. These results demonstrate that a temperature‐responsive flavour delivery system can be prepared with different PO melting points. The molecular dynamics of flavour release revealed that storage temperature and fat crystalline state impact the cumulative release rate of D‐limonene.

T. Schmid, M. Kinner, Luca Stäheli et al.

Palm fat has uniquely optimal melting characteristics that are difficult to replace in products such as baked goods and chocolate-based items. This study investigates the efficacy of using Pickering emulsions derived from Swiss plant oils and their micromilled press cakes. Emulsification was carried out at both the lab and pilot scales using sunflower- and rapeseed-based recipes, with and without additional surfactants, for both oil-in-water and water-in-oil emulsions. The resulting emulsions were measured for viscosity and short- and long-term stability and linked to the properties of the raw materials. The results indicated that the contact angle, size, and macronutrient composition of the particles significantly impact emulsion quality, though differences in oil pressing methods might predominate these effects. The combination of particles and surfactants demonstrated a clear advantage with respect to interface stabilisation, with a suggested link between the wax content of the oil and particles and the resulting emulsion quality and stability.

C. Talens, S. Álvarez-Sabatel, Esther Sanmartín et al.

ABSTRACT The prevalence of diet‐related health issues has driven the demand for healthier food options, particularly those with reduced fat content. This systematic review evaluates the integration of sensory analysis in low‐fat emulsion research, highlighting a significant gap in current practices. From an initial pool of 400 articles, 227 unique studies were screened, but only 15 (6.6%) included sensory analysis, underscoring a major shortfall in evaluating consumer acceptance. The reviewed studies investigated various emulsion types, including simple emulsions, emulsion gels, and Pickering emulsions, utilizing a diverse range of fat replacers, such as plant‐based oils, proteins, and modified starches. These fat replacers included natural and modified ingredients such as banana peel flour, lard‐based diacylglycerols, cedar oil cake, microparticulated egg white proteins, Nigella sativa oil, avocado, whey protein, flaxseed oil, polyphenol extracts, okara, microcrystalline wax and cellulose, rapeseed cake, and polysaccharide nanoparticles. These innovative approaches aimed to improve the sensory attributes of meat products, dairy‐type applications, salad dressings, and bakery products. The review highlights a disparity in the rigor and comprehensiveness of sensory evaluations among studies. While some studies have thoroughly assessed multiple attributes, others have been limited to general acceptability. This variability underscores the need for standardized, detailed sensory analysis in low‐fat emulsion research to ensure a comprehensive understanding of consumer preferences and product quality.

Guillermo Garcia-Sanchez, Ana M. Mancho, Antonio G. Ramos et al.

The chaotic nature of ocean motion is a major challenge that hinders the discovery of spatio-temporal current routes that govern the transport of material. Certain material, such as oil spills, pose significant environmental threats and these are enhanced by the fact that they evolve in a chaotic sea, in a way which still nowadays is far from being systematically anticipated. Recently such an oil spill event has affected the Mediterranean coast of several Middle Eastern countries. No accidents were reported for these spills previous to their arrival at the coast, and therefore there was no hint of their origin. Modelling such an event, in which uncertainties are increased due to the lack of information on where and when the spills was produced, stretches available technologies to their limits, and requires the use of novel ideas that help to understand the essential features of oil and tar transport by ocean currents. In this regard Lagrangian Coherent Structures enable us to find order within ocean chaos and provide powerful insights into chaotic events and their relationships over different locations and times like the one addressed. Using the observed locations of the oil impacting the coast at specific times, we seek to determine its original location and the time it was released in the open ocean. We have determined both using a combination of earlier satellite observations and computational modelling of the time evolution. The observed agreement between modeled cases and satellite observations highlights the power of these ideas.

Jonas Ekeland Kittelsen, Eric Aislan Antonelo, Eduardo Camponogara et al.

Neural networks, while powerful, often lack interpretability. Physics-Informed Neural Networks (PINNs) address this limitation by incorporating physics laws into the loss function, making them applicable to solving Ordinary Differential Equations (ODEs) and Partial Differential Equations (PDEs). The recently introduced PINC framework extends PINNs to control applications, allowing for open-ended long-range prediction and control of dynamic systems. In this work, we enhance PINC for modeling highly nonlinear systems such as gas-lifted oil wells. By introducing skip connections in the PINC network and refining certain terms in the ODE, we achieve more accurate gradients during training, resulting in an effective modeling process for the oil well system. Our proposed improved PINC demonstrates superior performance, reducing the validation prediction error by an average of 67% in the oil well application and significantly enhancing gradient flow through the network layers, increasing its magnitude by four orders of magnitude compared to the original PINC. Furthermore, experiments showcase the efficacy of Model Predictive Control (MPC) in regulating the bottom-hole pressure of the oil well using the improved PINC model, even in the presence of noisy measurements.

V. Jenning, A. Thünemann, S. Gohla

Xueqian Su, Farah Toublan, Yun Yin et al.

Siavash Hosseini, Thangarajah Akilan

Global oil demand is rapidly increasing and is expected to reach 106.3 million barrels per day by 2040. Thus, it is vital for hydrocarbon extraction industries to forecast their production to optimize their operations and avoid losses. Big companies have realized that exploiting the power of deep learning (DL) and the massive amount of data from various oil wells for this purpose can save a lot of operational costs and reduce unwanted environmental impacts. In this direction, researchers have proposed models using conventional machine learning (ML) techniques for oil production forecasting. However, these techniques are inappropriate for this problem as they can not capture historical patterns found in time series data, resulting in inaccurate predictions. This research aims to overcome these issues by developing advanced data-driven regression models using sequential convolutions and long short-term memory (LSTM) units. Exhaustive analyses are conducted to select the optimal sequence length, model hyperparameters, and cross-well dataset formation to build highly generalized robust models. A comprehensive experimental study on Volve oilfield data validates the proposed models. It reveals that the LSTM-based sequence learning model can predict oil production better than the 1-D convolutional neural network (CNN) with mean absolute error (MAE) and R2 score of 111.16 and 0.98, respectively. It is also found that the LSTM-based model performs better than all the existing state-of-the-art solutions and achieves a 37% improvement compared to a standard linear regression, which is considered the baseline model in this work.

Roberto Colomboni, Emmanuel Esposito, Andrea Paudice

The fat-shattering dimension characterizes the uniform convergence property of real-valued functions. The state-of-the-art upper bounds feature a multiplicative squared logarithmic factor on the sample complexity, leaving an open gap with the existing lower bound. We provide an improved uniform convergence bound that closes this gap.

Sarit Maitra, Vivek Mishra, Sukanya Kundu et al.

This work adopts a novel approach to determine the risk and return of crude oil stocks by employing Arbitrage Pricing Theory (APT) and Quantile Regression (QR).The APT identifies the underlying risk factors likely to impact crude oil returns.Subsequently, QR estimates the relationship between the factors and the returns across different quantiles of the distribution. The West Texas Intermediate (WTI) crude oil price is used in this study as a benchmark for crude oil prices. WTI price fluctuations can have a significant impact on the performance of crude oil stocks and, subsequently, the global economy.To determine the proposed models stability, various statistical measures are used in this study.The results show that changes in WTI returns can have varying effects depending on market conditions and levels of volatility. The study highlights the impact of structural discontinuities on returns, which can be caused by changes in the global economy and the demand for crude oil.The inclusion of pandemic, geopolitical, and inflation-related explanatory variables add uniqueness to this study as it considers current global events that can affect crude oil returns.Findings show that the key factors that pose major risks to returns are industrial production, inflation, the global price of energy, the shape of the yield curve, and global economic policy uncertainty.This implies that while making investing decisions in WTI futures, investors should pay particular attention to these elements

Joel Jean-Philyppe

A computational model is developed to assist the design of the first hybrid rocket engine of the McGill Rocket Team, using liquid nitrous oxide as an oxidizer and solid paraffin wax as a fuel. The model is developed in three phases: In the first phase, a steady-state model which neglects transient performance decrease of the hybrid engine is considered. The steady-state model considers: a constant oxidizer mass flow rate; a combustion chamber in chemical equilibrium; a one-dimensional isentropic nozzle; and a one-dimensional constant-thrust rocket ascent. The steady-state model is used to conduct parametric studies on engine performance as a function of design parameters such as: oxidizer mass flow rate, fuel grain dimensions, and nozzle dimensions. The engine design point is selected to optimize specific impulse, given physical and structural constraints of the system. In the second phase, an unsteady model incorporating transient performance decrease of the hybrid engine is considered. The transient model considers: a self-pressurizing oxidizer tank in quasi-steady liquid-vapor equilibrium; a combustion chamber in quasi-steady chemical equilibrium; a one-dimensional non-isentropic nozzle; and a one-dimensional rocket ascent model. The transient performance profile of the engine is established, and the unsteady model is used to predict propellant requirements for the launch vehicle, given a target apogee of 3048 m (10,000 ft). In the third stage, the unsteady model is compared to hot fire testing data of the McGill Rocket Team. Semi-empirical parameters used in the formulation are calibrated against testing data, and the validity of the model is assessed.

Jochem G. Meijer, Yanshen Li, Christian Diddens et al.

When an immiscible oil drop is immersed in a stably stratified ethanol-water mixture, the Marangoni flow on the surface of the drop can experience an oscillatory instability, so that the drop undergoes a transition from levitating to bouncing. The onset of the instability and its mechanisms have been studied previously, yet the bouncing motion of the drop itself, which is a completely different problem, has not yet been investigated. Here we study how the bouncing characteristics (jumping height, rising and sinking time) depend on the control parameters (drop radius, stratification strength, drop viscosity). We first record experimentally the bouncing trajectories of drops of different viscosities in different stratifications. Then a simplified dynamical analysis is performed to get the scaling relations of the jumping height and the rising and sinking times. The rising and sinking time scales are found to depend on the drag coefficient of the drop $C_D^S$ in the stratified liquid, which is determined empirically for the current parameter space. For low viscosity (5 cSt) oil drops the results on the drag coefficient match the ones from the literature. For high viscosity (100 cSt) oil drops the parameter space had not been explored and the drag coefficients are not readily available. Numerical simulations are therefore performed to provide external verification for the drag coefficients, which well match with the experimental results.