Mach 4 Simulating Experiment of Pre-Cooled Turbojet Engine Using Liquid Hydrogen

This study investigated a pre-cooled turbojet engine for a Mach 5 class hypersonic transport aircraft. The engine was demonstrated under takeoff and Mach 2 flight conditions, and a Mach 5 propulsion wind tunnel test is planned. The engine is composed of a pre-cooler, a core engine, and an afterburner. The engine was tested under simulated Mach 4 conditions using an air supply facility. High-temperature air under high pressure was supplied to the engine components through an airflow control valve and an orifice flow meter, and liquid hydrogen was supplied to the pre-cooler and the core engine. The results confirmed that the starting sequence of the engine components was effective under simulated Mach 4 conditions using liquid hydrogen fuel. The pre-cooling effect caused no damage to the rotating parts of the core engine in the experiment.

Advances in ultra-high temperature ceramics, composites, and coatings

Ultra-high temperature ceramics (UHTCs) are generally referred to the carbides, nitrides, and borides of the transition metals, with the Group IVB compounds (Zr & Hf) and TaC as the main focus. The UHTCs are endowed with ultra-high melting points, excellent mechanical properties, and ablation resistance at elevated temperatures. These unique combinations of properties make them promising materials for extremely environmental structural applications in rocket and hypersonic vehicles, particularly nozzles, leading edges, and engine components, etc. In addition to bulk UHTCs, UHTC coatings and fiber reinforced UHTC composites are extensively developed and applied to avoid the intrinsic brittleness and poor thermal shock resistance of bulk ceramics. Recently, highentropy UHTCs are developed rapidly and attract a lot of attention as an emerging direction for ultra-high temperature materials. This review presents the state of the art of processing approaches, microstructure design and properties of UHTCs from bulk materials to composites and coatings, as well as the future directions.

PENGARUH TEMPERATUR TUANG TERHADAP POROSITAS, STUKTUR MIKRO DAN KEKERASAN DARI ALUMUNIUM RONGSOK VELG MENGGUNAKAN PENGECORAN EVAPORATIF

The second largest metal material used after steel is Aluminum and its alloys. Ranging from aircraft bodies, vehicles, engine components, ship components, to buildings and very diverse applications using aluminum alloys. Material for making alloy wheels for components in motors using one of the special aluminum alloy applications with regard to the strength and hardness of high-quality aluminum alloys. Industrial companies that make aluminum doors, including windows and frames, make aluminum shelves, storefronts and other products. Produce waste remnants of used aluminum which can be used as aluminum as the main material destination. To reduce the company's production costs, many of them use aluminium scrap as their main casting material. Casting uses a temperature of 650 ° C, 700 ° C, 750 ° C, 800 ° C including casting type evaporative or casting using Styrofoam. The missing styrofoam casting pattern is a casting that uses a pattern of material that can evaporate when exposed to molten metal heat. The casting temperature results can affect microstructure, hardness, porosity and structure.

Aerothermodynamics and Jet Propulsion

Get up to speed with this robust introduction to the aerothermodynamics principles underpinning jet propulsion, and learn how to apply these principles to jet engine components. Suitable for undergraduate students in aerospace and mechanical engineering, and for professional engineers working in jet propulsion, this textbook includes consistent emphasis on fundamental phenomena and key governing equations, providing students with a solid theoretical grounding on which to build practical understanding; clear derivations from first principles, enabling students to follow the reasoning behind key assumptions and decisions, and successfully apply these approaches to new problems; practical examples grounded in real-world jet propulsion scenarios illustrate new concepts throughout the book, giving students an early introduction to jet and rocket engine considerations; and online materials for course instructors, including solutions, figures, and software resources, to enhance student teaching.

PRODUCT QUALITY CONTROL USING SIX SIGMA (DMAIC) METHODS TO MINIMIZE WAST IN BIMA MANDIRI CIGARETTE COMPANY REMBANG, PASURUAN REGENCY

Quality is a key to be able to compete in the industrial world [16. Quality control is needed to reduce the number of defective products produced by the company, thus reducing losses experienced by the company. The Bima Mandiri Rembang Pasuruan cigarette company is a company that produces cigarettes, one of which is INNO cigarettes. The number of defective products produced by the company so that the company must make an increase in quality by using a method to reduce the number of defects that occur. The number of defective products causes the company to suffer losses. For that, we need a method that can reduce cigarette defective products which in turn can improve the quality of the company's production[12]. Six Sigma with the DMAIC stage (Define, Measure, Analyze, Improve, Control) is a method used in this research. Based on these steps, defects that often occur are less dense cigarettes as many as 289 sticks with a percentage of 25%, tearing on the cigarettes as many as 227 cigarettes with a percentage of 20% and peeling cigarettes as many as 208 sticks with a percentage of 18%. Factors that cause defects include humans, machines, methods and materials. After calculating using the Six Sigma method, before the improvement, the DPMO value is 113988.1 and the Sigma Level value is 2.722. After the improvements were made, the DPMO value decreased to 76488.1 and the Sigma Level was 2.94715. To achieve the six sigma target, the company is expected to be able to carry out improvements with a focus on the factors that cause product defects and always carry out regular control to reduce product defects. The corrective steps taken in the Bima Mandiri Rembang Pasuruan Regency cigarette company are human: regular training for machine operators and employees; methods: inspection of raw materials, blending machines and glue residue in the teat; engine: inspection of engine components; material: reprocessing less refined raw materials and using better quality glue.

Friction and Wear Performance Evaluation of Bio-Lubricants and DLC Coatings on Cam/Tappet Interface of Internal Combustion Engines

The environmental concerns associated with artificially formulated engine oils have forced a shift towards bio-based lubricants. The deposition of hard coatings on engine components and migrating to environmentally friendly green lubricants can help in this regard. Chemically modified forms of vegetable oils, with better low-temperature characteristics and enhanced thermo-oxidative stability, are suitable substitutes to conventional lubricant base oils. The research presented in this manuscript was undertaken to experimentally investigate the wear and friction performance of a possible future generation of an environmentally friendly bio-based lubricant as a potential replacement for conventional engine lubricants. In order to quantify the tribological benefits which can be gained by the deposition of DLC coatings, (an (a-C:H) hydrogenated DLC coating and an (a-C:H:W) tungsten-doped DLC coating) were applied on the cam/tappet interface of a direct acting valve train assembly of an internal combustion engine. The tribological correlation between DLC-coated engine components, lubricant base oils and lubricant additives have been thoroughly investigated in this study using actual engine operating conditions. Two additive-free base oils (polyalphaolefines (PAO) and chemically-modified palm oil (TMP)) and two multi-additive-containing lubricants were used in this investigation. Real-time drive torque was measured to determine the friction force, detailed post-test analysis was performed, which involved the use of a specialized jig to measure camlobe wear. An optical profilometer was used to measure the wear on the tappet, high-resolution scanning electron microscopy was employed to study the wear mechanism and energy-dispersive X-ray spectroscopy was performed on the tested samples to qualitatively access the degradation of the coating. When using additive-free TMP, a low friction coefficient was observed for the cam/tappet interface. The presence of additives further improved the friction characteristics of TMP, resulting in reduced average friction torque values. A tremendous enhancement in wear performance was recorded with a-C:H-coated parts and the coating was able to withstand the test conditions with little or no delamination.