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  • Author: Guoqiang He x
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Abstract

The vortex valve solid variable thrust motor is a new solid motor which can achieve Vehicle system trajectory optimization and motor energy management. Numerical calculation was performed to investigate the influence of vortex chamber diameter, vortex chamber shape, and vortex chamber height of the vortex valve solid variable thrust motor on modulation performance. The test results verified that the calculation results are consistent with laboratory results with a maximum error of 9.5%. The research drew the following major conclusions: the optimal modulation performance was achieved in a cylindrical vortex chamber, increasing the vortex chamber diameter improved the modulation performance of the vortex valve solid variable thrust motor, optimal modulation performance could be achieved when the height of the vortex chamber is half of the vortex chamber outlet diameter, and the hot gas control flow could result in an enhancement of modulation performance. The results can provide the basis for establishing the design method of the vortex valve solid variable thrust motor.

Abstract

Fully integrated numerical simulations were performed for a ready-made central strut-based rocket-based combined-cycle (RBCC) engine operating in ejector mode, and the applicability of using a boundary layer bleed in the RBCC inlet designed for supersonic speeds was investigated in detail. The operational mechanism of the boundary layer bleed and its effects on the RBCC inlet and the engine under different off-design conditions in ejector mode were determined. The boundary layer bleed played different roles in the RBCC inlet for different flight regimes. When the RBCC engine took off, some air was entrained into the inlet through the bleed block, thereby inducing significant flow separation and a low-speed vortex, which deteriorated the inner flow and reduced the entraining air mass flow rate: thus, the total pressure loss increased and extra drag was exerted on the inlet. In the low subsonic regime, the bleed block had almost no impact on the RBCC engine and its inlet. However, as the RBCC engine accelerated into a high subsonic flight regime, the boundary layer bleed had a clearly positive effect, comprehensively improving the performance of the RBCC inlet. A boundary layer bleed operation strategy for the RBCC inlet in ejector mode was also developed in this study.

Abstract

Background: DNA somatic mutations of EGFR, KRAS, BRAF and PIK3CA in the epidermal growth factor receptor (EGFR) signaling pathway play critical roles in the response or resistance of tumors to targeted therapy with tyrosine kinase inhibitors (EGFR-TKIs). To provide a high-throughput (HTP) clinical testing service for detecting these mutations, we developed a novel platform, SurPlex ®-xTAG70plex-EGFR liquidchip.

Methods: This platform was developed based on a universal 100-tag system. The procedures for multiplex PCR, allele specific primer extension (ASPE) and hybridization were optimized and standardized.

Results: A total of 70 alleles of somatic mutations of EGFR, KRAS, BRAF and PIK3CA can be detected simultaneously in one reaction from one formalin-fixed and paraffin-embedded (FFPE) slide within one day. Cross-reaction was <8% between individual amplimers and 70 different ASPE primers. The sensitivity for detecting mutants in the wild-type DNA was 1%–5%. Seventy-three FFPE samples with somatic mutations were used to validate the 70plex. Seventy-one showed a complete match, while two were not detected.

Conclusions: A simple, accurate, sensitive HTP technology was developed and standardized for detecting simultaneously 70 different alleles of EGFR, KRAS, BRAF and PIK3CA gene mutations from FFPE tumor slides.

Abstract

Thermal choke is commonly employed in a fixed geometry RBCC combustor to eliminate the need for physically variable exit geometry. This paper proposed detailed numerical studies based on a two-dimensional integration model to characterize thermal choke behaviors driven by various embedded rocket operations in an RBCC engine at Mach 4 in ramjet mode. The influences of different embedded rocket operations as well as the corresponding secondary fuel injection adjustment on thermal choke generation process, the related thermal throat feature, and the engine performance are analyzed. Operations of embedded rocket bring significant effects on the thermal choke behaviors: (1) the thermal throat feature becomes much more irregular influenced by the rocket plume; (2) the occupancy range in the combustor is significantly lengthened; (3) the asynchrony of the flow in different regions accelerating to sonic speed becomes much more significant; (4) as the rocket throttling ratio decreases, the thermal choke position constantly moves upstream integrally, and the heated flow in the top region that is directly affected by the rocket plume reaches sonic speed more rapidly. Finally, we can conclude that appropriate secondary fuel injection adjustment can provide a higher integration thrust for the RBCC engine with the embedded rocket operating, while the thermal choke is stably controlled, and the increased heat release and combustion pressure are well balanced by the variations of pre-combustion shocks in the inlet isolator.

Abstract

A widely applicable and variable geometry 2-D rocket based combined cycle (RBCC) inlet characterized by the dual-duct design is conceptually put forward. The inlet operates as dual-duct status in the low Mach range (0~4), and transits to single-flowpath status in the following high Mach range (4~7). It accomplishes operational status transition through an 8.0-degree ramp rotation and a 4.0-degree cowl rotation at Mach 4. Through numerical simulations on typical flight Mach numbers, the observed starting Mach number is 2.2, which provides a sufficient operational window for a smooth ejector-to-ramjet mode transition. The RBCC inlet achieves comprehensive high mass capture coefficients in the overall wide flight range, especially in the low speed regimes. Suitable Mach numbers satisfying various combustion requirements in different modes together with high total pressure recovery coefficients are also obtained since the physical throat areas, compression angles, and the corresponding contraction ratios can be adjusted by a large margin through very limited rotations. The variable geometry scheme is not only feasible for practical realizations, but is also simple to arrange the dynamic sealing issues in a low-temperature environment in the RBCC engine.

Abstract

Numerical integration simulations were performed on a ready-made central strut-based rocket-based combined-cycle (RBCC) engine operating in the ejector mode during the takeoff regime. The effective principles of various cowl lip positions and shapes on the inlet operation and the overall performance of the entire engine were investigated in detail. Under the static condition, reverse cowl lip rotation in a certain range was found to contribute comprehensive improvement to the RBCC inlet and the entire engine. However, the reverse rotation of the cowl lip contributed very little enhancement of the RBCC inlet under the low subsonic flight regime and induced extremely negative impacts in the high subsonic flight regime, especially in terms of a significant increase in the drag of the inlet. Changes to the cowl lip shape provided little improvement to the overall performance of the RBCC engine, merely shifting the location of the leeward area inside the RBCC inlet, as well as the flow separation and eddy, but not relieving or eliminating those phenomena. The results of this study indicate that proper cowl lip rotation offers an efficient variable geometry scheme for a RBCC inlet in the takeoff regime.

Abstract

Chinese biochemical engineering is committed to supporting the chemical and food industries, to advance science and technology frontiers, and to meet major demands of Chinese society and national economic development. This paper reviews the development of biochemical engineering, strategic deployment of these technologies by the government, industrial demand, research progress, and breakthroughs in key technologies in China. Furthermore, the outlook for future developments in biochemical engineering in China is also discussed.