scholarly journals A Numerical Study for Flow Excitation and Performance of Rampressor Inlet considering Rotor Motion

2014 ◽  
Vol 2014 ◽  
pp. 1-16 ◽  
Author(s):  
Weijia Kang ◽  
Zhansheng Liu ◽  
Jiangbo Lu ◽  
Yu Wang ◽  
Yanyang Dong
Keyword(s):  
Power Systems ◽  
Fundamental Frequency ◽  
Numerical Study ◽  
Pressure Ratio ◽  
Frequency Component ◽  
Inlet Flow ◽  
Compressor Rotor ◽  
Frequency Components ◽  
Subsonic Diffuser ◽  
And Performance

A unique supersonic compressor rotor with high pressure ratio, termed the Rampressor, is presented by Ramgen Power Systems, Inc. (RPS). In order to obtain the excitation characteristic and performance of Rampressor inlet flow field under external excitation, compression inlet flow of Rampressor is studied with considering Rampressor rotor whirling. Flow excitation characteristics and performance of Rampressor inlet are analyzed under different frequency and amplitude of Rampressor rotor whirling. The results indicate that the rotor whirling has a significant effect for flow excitation characteristics and performance of Rampressor inlet. The effect of rotor whirling on the different inlet location excitation has a definite phase difference. Inlet excitation becomes more complex along with the inlet flow path. More frequency components appear in the excitation spectrum of Rampressor inlet with considering Rampressor rotor whirling. The main frequency component is the fundamental frequency, which is caused by the rotor whirling. Besides the fundamental frequency, the double frequency components are generated due to the coupling between inlet compression flow of Rampressor rotor and rotor whirling, especially in the subsonic diffuser of Rampressor rotor inlet. With the increment of rotor whirling frequency and whirling amplitude, the complexity of Rampressor inlet excitation increases, and the stability of Rampressor inlet performance deteriorates.

A Numerical Study on the Effect of Bleed System on Starting Ability and Flow Performance of Rampressor Inlet

2014 ◽  
Vol 136 (12) ◽  
Author(s):  
Weijia Kang ◽  
Zhansheng Liu ◽  
Yu Wang ◽  
Yanyang Dong ◽  
Yong Sun
Keyword(s):  
Boundary Layer ◽  
Power Systems ◽  
Numerical Study ◽  
Pressure Ratio ◽  
Work Condition ◽  
High Pressure Ratio ◽  
Compressor Rotor ◽  
Improvement Effect ◽  
Negative Effect ◽  
Computational Fluid Dynamics Cfd

A unique supersonic compressor rotor with high pressure ratio, termed the Rampressor, is presented by Ramgen Power Systems, Inc., (RPS). Based on the models of Rampressor inlet, the inlet flow field with bleed system is numerically studied. Validation of the employed computational fluid dynamics (CFD) scheme is provided through test cases. The effects of boundary layer bleed location and bleed amount on Rampressor rotor inlet start and flow performance are analyzed. The results indicate that the boundary layer bleed has a significant effect for start and flow performance of Rampressor inlet. Boundary layer bleed technique has been applied to eliminate the emerging flow separation zone for enhancing Rampressor rotor inlet performance and enlarging its stable working range. The starting ability and flow performance of Rampressor inlet are efficiently improved by bleeding system, but the improvement effect is different for Rampressor inlet with different bleed location. Along the position of bleeding system moves forward, the range of Rampressor inlet normal work rotation speed is enlarged. The flow performance of Rampressor inlet improves obviously with the increment of bleed flow rate, and exit stability of Rampressor inlet enhances. And in the same back pressure work condition of Rampressor inlet, bleed system has been shown to be effective that exit stability of Rampressor inlet ameliorates, but the loss of compressed air from the bleed system has a negative effect on overall Rampressor inlet efficiency.

Effect of Tip Clearance Size on the Ram-Rotor Performance

2014 ◽  
Author(s):  
Ji-ang Han ◽  
Jing-jun Zhong ◽  
Zhen-sheng Pan ◽  
Ling Yang ◽  
Jian Guan
Keyword(s):  
Shock Wave ◽  
Power Systems ◽  
High Performance ◽  
Stokes Equations ◽  
Pressure Ratio ◽  
Energy System ◽  
Tip Clearance ◽  
Performance Parameters ◽  
Flow Parameters ◽  
And Performance

The ram-rotor presented by Ramgen Power Systems, Inc. is a new kind of compression system based on shock wave compression technology commonly used in supersonic intakes. Compared to conventional axial and centrifugal compressors, it has a simple and compact configuration, and also has advantages of the higher single stage pressure ratio, small volume and light weight. However, its efficiency should be further improved. Based on its inherent advantages, the ram-rotor can be widely used in small aero-engine, medium and small shipping power system, micro gas turbine employed by distributed energy system and power plant in the future. In this paper, the flow field and performance of a ram-rotor with different tip clearance sizes are simulated numerically by adopting the three dimensional Reynolds-averaged Navier-Stokes equations and the Spalart-Allmaras turbulent model at the design condition. The purpose of numerical simulation is to investigate the flow details and performance parameters of the ram-rotor under different tip clearance sizes, including the structure of the shock wave, the size and location of flow separation zone, radial distribution of flow parameters at the outlet of the ram-rotor, the characteristics of tip clearance leakage flow, and so on. It has been found that the performance of the ram-rotor is very sensitive to the tip clearance size. The overall performance parameters of the ram-rotor decrease greatly with the increase of the tip clearance size. So, the selection of suitable tip clearance size is one of the key issues in obtaining a high performance of the ram-rotor in the design process. For the ram-rotor with tip clearance, the reflection structure of the shock wave will be destroyed. The flow loss of tip region will be increased with the increase of the tip clearance size. For the ram-rotor with and without tip clearance, the flow parameters distribution trend along the radial direction at the outlet is different.

Effect of Water-Cooling Turbine Blades on Advanced Gas Turbine Power Systems

1977 ◽  
Author(s):  
B. V. Johnson ◽  
A. J. Giramonti ◽  
S. J. Lehman
Keyword(s):  
Power Systems ◽  
Gas Turbine ◽  
Pressure Ratio ◽  
Turbine Blades ◽  
Combined Cycle ◽  
Air Cooling ◽  
Water Cooling ◽  
Gas Turbine Blades ◽  
And Performance ◽  
Cycle Efficiency

A study was conducted to determine what benefits in cycle efficiency and performance could be obtained with water-cooled gas turbine blades. Water cooling was compared against various degrees of air cooling and the ultimate limit of no cooling. Performance studies were conducted for both combined gas turbine-steam cycles and simple gas turbine cycles with temperatures at the inlet to the first turbine blade row from 1478 K (2200 F) to 1922 (3000 F) and compressor pressure ratios from 12 to 28. Results for both types of cycles indicated that absolute efficiencies 1 to 3 percentage points greater and power output per unit airflow 5 to 25 percent greater than could be obtained with water-cooled blades compared to air-cooled blades. For a given cooling scheme and pressure ratio, highest efficiencies were obtained at 1700 K (2600 F) for the simple cycle and 1922 K for the combined cycle.

scholarly journals Flow Field and Performance of a Centrifugal Compressor Rotor With Tandem Blades of Adjustable Geometry

1994 ◽  
Author(s):  
Burkhard Josuhn-Kadner
Keyword(s):  
Flow Field ◽  
Centrifugal Compressor ◽  
Pressure Ratio ◽  
Wake Flow ◽  
Compressor Stage ◽  
Centrifugal Compressor Stage ◽  
Compressor Rotor ◽  
Surge Margin ◽  
Bladed Rotor ◽  
And Performance

A centrifugal compressor stage has been investigated mainly experimentally for aerodynamic stage optimization. The rotor consists of a separate inducer with 14 blades and an impeller with 28 blades. Both rotor components can be locked with each other at different circumferential positions thus, forming either a conventional splitter blade rotor or a tandem bladed rotor of adjustable geometry. The influence of the tandem blade geometry on the rotor and stage characteristics is studied in detail. Laser-2-Focus-System measurements were performed at nine locations all over the rotor taking three different circumferential inducer positions into account. The improvement with the tandem blade configuration on the rotor and stage characteristics is small but significant differences in the flow field of the two different impeller channels in the rear and exit part of the rotor are recognizable. The velocity differences of the jet/wake flow are reduced by using tandem blades which lead to a slight increased stage pressure ratio and surge margin.

Performance Desensitization for a High-Speed Axial Compressor

2018 ◽  
Author(s):  
Yassine Souleimani ◽  
Huu Duc Vo ◽  
Hong Yu
Keyword(s):  
High Speed ◽  
Numerical Study ◽  
Pressure Ratio ◽  
Axial Compressor ◽  
Tip Clearance ◽  
Lower Sensitivity ◽  
Tip Leakage Flow ◽  
Stall Margin ◽  
Casing Treatment ◽  
Compressor Rotor

The increase in compressor tip clearance over the lifespan of an aero-engine leads to a long-term degradation in its fuel consumption and operating envelope. A highly promising recent numerical study on a theoretical high-speed axial compressor rotor proposed a novel casing treatment to decrease performance and stall margin sensitivity to tip clearance increase. This paper aims to apply and analyze, through CFD simulations, this casing treatment concept to a representative production axial compressor rotor with inherently lower sensitivity to tip clearance increase and complement the explanation on the mechanism behind the reduction in sensitivity. Simulations of the baseline rotor showed that the lower span region contribute as much to the pressure ratio sensitivity as the tip region which is dominated by tip leakage flow. In contrast, the efficiency sensitivity is mainly driven by losses occurring in the tip region. The novel casing treatment was successfully applied to the baseline rotor through a design refinement. Although the casing treatment causes some penalty in nominal performance, it completely reversed the pressure ratio sensitivity (i.e. pressure ratio increases with tip clearance) and reduced the efficiency sensitivity. The reversed pressure ratio sensitivity is explained by a rotation in the core flow in the lower span region indirectly induced by the flow injection from the casing treatment. The lower efficiency sensitivity comes from a reduction in the amount of fluid that crosses the tip clearance of two adjacent blades, known as double leakage. The casing treatment’s beneficial effect on stall margin sensitivity is less obvious because of the stall inception type of the baseline rotor and its change in the presence of the casing treatment.

scholarly journals Effect of Partial Span Aspiration on the Performance of a Transonic Axial Compressor Rotor: A Numerical Study

2015 ◽  
Vol 2015 ◽  
pp. 1-13
Author(s):  
Vijaykumar Jain ◽  
Quamber H. Nagpurwala ◽  
Abdul Nassar
Keyword(s):  
Boundary Layer ◽  
Numerical Study ◽  
Pressure Ratio ◽  
Axial Compressor ◽  
Suction Side ◽  
Surface Boundary ◽  
Suction Surface ◽  
Stall Margin ◽  
Compressor Rotor ◽  
Transonic Axial Compressor

Aspiration in an axial compressor is normally regarded as sucking out the low momentum boundary layer from blade suction surface, thus lowering the chances of flow separation and consequently that of stall under off-design operation. However, the suction mass flow does not take part in useful work and leads to loss of engine power output. This paper deals with a new concept of natural aspiration to energize blade suction surface boundary layer by injecting some fluid from pressure to suction side through a part span slot on the blade. The energized boundary layer has lesser tendency to separate, thus enhancing stall margin. Numerical simulations were carried out to study the effect of aspiration slot location and geometry on the performance and stall margin of a transonic axial compressor rotor. The computational results without aspiration slot were in fair agreement with the published experimental data. The modified rotor, with part span aspiration, showed ~3.2% improvement in stall margin at design rotational speed. The pressure ratio and efficiency of the aspirated rotor dropped by ~1.42% and ~2.0%, respectively, whereas the structural analysis did not indicate any adverse effect on the blade stress distribution in the presence of aspiration slot.

scholarly journals 5 MW Closed Cycle Gas Turbine

1984 ◽  
Author(s):  
John L. Mason ◽  
Anthony Pietsch ◽  
Theodore R. Wilson ◽  
Allen D. Harper
Keyword(s):  
Power Systems ◽  
Gas Turbine ◽  
Oil Recovery ◽  
Low Cost ◽  
Pressure Ratio ◽  
Commercial Application ◽  
Solid Fuels ◽  
Closed Cycle ◽  
Emission Standards ◽  
Fluidized Bed Combustor

A novel closed-cycle gas turbine power system is now under development by the GWF Power Systems Company for cogeneration applications. Nominally the system produces 5 megawatts (MW) of electric power and 80,000 lb/hr (36,287 kg/hr) of 1000 psig (6895 kPa) steam. The heat source is an atmospheric fluidized bed combustor (AFBC) capable of using low-cost solid fuels while meeting applicable emission standards. A simple, low-pressure ratio, single spool, turbomachine is utilized. This paper describes the system and related performance, as well as the development and test efforts now being conducted. The initial commercial application of the system will be for Enhanced Oil Recovery (EOR) of the heavy crudes produced in California.

scholarly journals Numerical Modeling and Performance Evaluation of Standing Wave Thermoacoustic Refrigerators with a Multi-Layered Stack

Energies ◽  
2020 ◽  
Vol 13 (17) ◽  
pp. 4360
Author(s):  
Umar Nawaz Bhatti ◽  
Salem Bashmal ◽  
Sikandar Khan ◽  
Rached Ben-Mansour
Keyword(s):  
Standing Wave ◽  
Numerical Study ◽  
Temperature Drop ◽  
Acoustic Power ◽  
Heat Energy ◽  
Coefficient Of Performance ◽  
Material Layer ◽  
And Performance ◽  
Stacked Material ◽  
Thermoacoustic Refrigerators

Thermoacoustic refrigerators have huge potential to replace conventional refrigeration systems as an alternative clean refrigeration technology. These devices utilize conversion of acoustic power and heat energy to generate the desired cooling. The stack plays a pivotal role in the performance of Standing Wave Thermoacoustic Refrigerators (SWTARs), as the heat transfer takes place across it. Performance of stacks can be significantly improved by making an arrangement of different materials inside the stack, resulting in anisotropic thermal properties along the length. In the present numerical study, the effect of multi-layered stack on the refrigeration performance of a SWTAR has been evaluated in terms of temperature drop across the stack, acoustic power consumed and device Coefficient of Performance (COP). Two different aspects of multi-layered stack, namely, different material combinations and different lengths of stacked layers, have been investigated. The combinations of four stack materials and length ratios have been investigated. The numerical results showed that multi-layered stacks produce lower refrigeration temperatures, consume less energy and have higher COP value than their homogeneous counterparts. Among all the material combinations of multi-layered stack investigated, stacks composed of a material layer with low thermal conductivity at the ends, i.e., RVC, produced the best performance with an increase of 26.14% in temperature drop value, reduction in the acoustic power consumption by 4.55% and COP enhancement of 5.12%. The results also showed that, for a constant overall length, an increase in length of side stacked material layer results in an increase in values of both temperature drop and COP.

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