A Study of the Impact of Methanol, Ethanol and the Miller Cycle on a Gasoline Engine

This paper focuses on the investigation and optimisation of the Miller cycle, methanol, ethanol and turbocharging when applied to a high-performance gasoline engine. These technologies have been applied both individually and concurrently to test for potential compounding effects. Improvements have been targeted with regards to both emission output and performance. Also assessed is the capability of the engine to operate when exclusively powered by biofuels. This has been carried out numerically using the 1D gas dynamics tool ‘WAVE’, a 1D Navier–Stokes equation solver. These technologies have been implemented within the McLaren M838T 3.8L twin-turbo engine. The Miller cycle early intake valve close (EIVC) improved peak efficiency by 0.17% and increased power output at low and medium loads by 11%. Reductions of 6% for both NOx and CO were also found at rated speed. The biofuels achieved NOx and CO reductions of 60% and 96% respectively, alongside an efficiency increase of 2.5%. Exclusive biofuel use was found to be feasible with a minimum 35% power penalty. Applied cooperatively, the Miller cycle and biofuels were not detrimental to each other, compounding effects of a further 0.05% efficiency and 2% NOx improvements were achieved.

An Experimental Investigation to Use the Biodiesel Resulting from Recycled Sunflower Oil, and Sunflower Oil with Palm Oil as Fuels for Aviation Turbo-Engines

The paper is presenting the experimental analysis of the use of biodiesel from waste sunflower oil and a blend of sunflower oil with palm oil as fuel for aviation turbo-engines. A comparative analysis for fuel mixtures made of Jet A + 5% Aeroshell 500 Oil (Ke) with 10%, 30%, and 50% for each bio-fuel type has been performed and Ke has been used as reference. Firstly, the following physical and chemical properties were determined: density, viscosity, flash point, freezing point, calorific power. Then, elemental analysis and Fourier transform infrared spectroscopy (FTIR) analysis were conducted for Ke, biodiesel obtained from recycled sunflower oil (SF), biodiesel obtained from blending recycled sunflower oil, and recycled palm oil (SFP), and for each fuel blend. Secondly, experimental tests of the blends have been conducted on the Jet Cat P80® micro-turbo engine (Gunt Hamburg, Barsbüttel, Germany). The tests have been conducted at different engine working regimes as follows: idle, cruise, intermediate, and maximum. For each regime, a one-minute testing period was chosen, and the engine parameters have been monitored. The turbo engine instrumentation recorded the temperature after the compressor and before the turbine, the fuel consumption and air flow, pressure inside the combustion chamber, and generated thrust. The burning efficiency and the specific consumption have been calculated for all four above-mentioned regimes and for all fuel blends. Two accelerometers have been installed on the engine’s support to register radial and axial vibrations allowing the assessment of engine stability.

Investigating the Use of Recycled Pork Fat-Based Biodiesel in Aviation Turbo Engines

This paper presents an analysis of the possibility of using recycled pork fat-based biodiesel as fuel for aviation turbo-engines. The analysis consists of the assessment of four blends of Jet A kerosene with 10%, 30%, 50%, and 100% biodiesel and pure Jet A that was used as reference in the study. The first part of the paper presents the physical-chemical properties of the blends: density, viscosity, flash point, freezing point, and calorific power. Through Fourier transform infrared spectroscopy (FTIR) analysis, a benchmark was performed on the mixtures of Jet A with 10%, 20%, 30%, 50%, and 100% biodiesel compared with Jet A. The second part of the paper presents the test results of these blends used for fuelling a Jet Cat P80 turbo engine at the Turbo Engines Laboratory of the Aerospace Engineering Faculty of Polyethnic University of Bucharest. These functional tests were performed using different operating regimes as follows: idle, cruise, intermediate, and maximum. For each regime, a testing period of around 1 min was selected and the engine parameters were monitored during the test execution. The burning efficiency was calculated for the maximum regime for all mixtures. To evaluate the functioning stability of the turbo engine using biodiesel, two accelerometers were mounted on the engine support that recorded the radial and axial vibrations. Moreover, to assess the burning stability and to identify other acoustic spectral components when biodiesel is used, two microphones were placed near the jet region. A comparative analysis between blends was made by taking the Jet A fuel as reference.

Experimental Study on Centrifugal Compressor Performance at Pulsating Backpressure Conditions

The flow in the intake manifold of a downsized internal combustion engine has become more unsteady due to the reduction of cylinder number and increasing boosting level. The turbocharger compressor is thus imposed by an unsteady backpressure when matched with an engine. It has been experimentally confirmed that the compressor performance is affected when exposed to pulsating backpressure. In order to enhance compressor stability and achieve better turbo-engine matching, it is necessary to understand behaviors of compressor at pulsating backpressure conditions. In this study, the performance of compressor exposed to pulsating backpressure is experimentally studied on the compressor test rig located in Shanghai Jiao Tong University. The results show that compressor performance with pulsating backpressure is notably different from the one with constant backpressure. Hysteresis loops which encapsulate the steady performance are generated at pulsating backpressure conditions due to filling-emptying effect. The mass flow rate, pulse frequency and compressor rotational speed all have evident influence on dynamic behaviors of the compressor. As the mass flow rate and rotational speed increase, hysteresis loops are enlarged and the unsteady behaviors are enhanced. The influence of pulsating backpressure on the compressor surge margin is analyzed in detail. Results demonstrate that the stable operation range is evidently influenced by the pulsating backpressure. Particularly, the mass flow rate of surge is postponed by 15.1% compared with the corresponding constant backpressure condition. Fast Fourier Transform method (FFT) is applied to identify the initiation of surge. The frequency domain analysis proves that the pulsating backpressure has little influence on the frequency of surge, but the strength of surge is alleviated indicated by the magnitude of fluctuations. The study provides an insight on the influence of pulsating backpressure on the centrifugal compressor, which can benefit the design methodology of compressor as well as turbo-engine matching.