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The grain design of hybrid rocket motor is a design of proper fuel grain geometry and flow adjustment scheme based on the total impulse, thrust, chamber pressure, length and outer diameter of combustion chamber. And the laws of various parameters in the working process of motor are obtained through the internal ballistic calculation. Based on the overall indicators of the upper stage motor of launch vehicles, the grain design process of single wagon-wheel and the internal ballistic calculation of adjusting the oxidizer flow according to the thrust feedback under the preset thrust condition are established. According to the indicators of power system, the constant thrust is F=11kN, the total impulse is I≥1100kN·s, the outer diameter is Dt≤400mm and the chamber length is L≤1000mm. Furthermore, the comparison and optimization design on star-shaped and single wagon-wheel grain are carried out. The oxidizer is 98% hydrogen peroxide (HP), the fuel is hydroxyl-terminated polybutadiene (HTPB) based fuel (including 58% Al), and the optimal oxygen-fuel ratio (O/Fopt) is 1.3. According to the theory of constant regression rate of the burning surface, the changes of the burning line length and channel area of the single wagon-wheel grain with the regression of the combustion surface are calculated. The results show that when the expansion ratio is 100 and average combustion chamber pressure is 5 MPa, the burning area of single wagon-wheel grain increases by 16.9% compared with the star-shaped grain, the O/F is reduced during motor operation, and the average specific impulse of the engine is increased by nearly 2%. In this paper, a typical uniform-thickness single wagon-wheel fuel grain is adopted. According to the optimization design, when the spokes number is 6, the average specific impulse of the motor is the largest. With increasing the spokes angle coefficient, increasing the height of the spokes, and reducing the angle of the spokes, the burning area is increased and the channel area is reduced, thereby the regression rate and fuel flow are increased and the O/F is reduced during the working process. Then the average specific impulse and overall performance are improved. This research provides a reference for single wagon-wheel fuel grain of hybrid rocket motor, calculation of interior ballistic performance under preset thrust, and flow adjustment by thrust feedback.

Rice wine, known as yellow wine in China and Japan, possesses considerable nutritional value and holds significant global influence. This study addresses the challenge of preserving rice wine, which is prone to rancidity due to its low alcohol content. Conventional storage techniques employing pottery jars often result in substantial spoilage losses. Through rigorous investigation, this research identifies a polarization phenomenon exhibited by degraded rice wine when subjected to high-frequency microwaves(>60GHz), presenting a pioneering method for detecting spoilage, even within sealed containers. Employing a multi-channel microwave radar apparatus, the study delves into the susceptibility of rice wine to electromagnetic waves across various frequencies, uncovering pronounced polarization traits in deteriorated samples within the E-band microwave spectrum. Furthermore, lab-controlled simulations elucidate a direct correlation between physicochemical alterations and high-frequency Radar Cross Section (RCS) signals during the wine's deterioration process. A novel six-membered Hydrated Cluster hypothesis is proposed, offering insights into the molecular mechanisms underlying this phenomenon. Additionally, dielectric property assessments conducted using vector network analyzers (VNA) reveal noteworthy enhancements in the dielectric constant of deteriorated rice wine, particularly within the high-frequency domain, thereby augmenting detectability. These findings carry implications for refining rice wine preservation techniques and contribute to the advancement of non-destructive testing technologies, enabling the detection of rice wine deterioration or indications thereof, even within sealed vessels. [ABSTRACT FROM AUTHOR]

This study investigated reconstruction techniques for building the instantaneous fuel regression rate of the hybrid rocket motor (HRM). Specifically, an experiment in a laboratory 500 N-class hybrid rocket motor with single-port wagon wheel fuel grain, operated with hydrogen peroxide (HP) and hydroxyl-terminated polybutadiene (HTPB) based fuel (including Al), was carried out. A piece of post-processing software was developed to reconstruct the instantaneous regression rate and other performance parameters of the HRM during the firing test. The results produced by the reconstruction techniques are in good agreement with experimental data obtained by traditional methods, with a maximum error of less than 5.75%. Moreover, compared with the traditional endpoint method, the reconstruction method had a significant advantage, which could ascertain the sensitivity of the regression rate to changes in the oxidizer mass flux and fit the formula of regression rate in a single firing test. Additionally, digital image processing techniques were employed to determine the axial distribution of the fuel regression rate after the test using computed tomography (CT) scanning. This served to verify the accuracy of the instantaneous reconstruction calculation. The error in the average regression rate between CT scanning and the reconstruction calculation was 1.91%, proving that the CT scanning and pixel statistic method of the calculating regression rate was practical for characterizing the axial distribution of the average regression rate during the firing test. In summary, the main objective of this study was to reconstruct the transient parameters of hybrid rocket motor with single-port wagon wheel fuel grain using reconstruction techniques, and to fit the formula of the regression rate through a single-firing test. Furthermore, this paper proposes a modified reconstruction method that is essential for investigating fuel regression rate during the firing test of HRMs. [ABSTRACT FROM AUTHOR]