HP Compressor Research Articles

Aerothermodynamic and rotordynamic performance evaluation to diagnose deposits accumulation in a gas lift centrifugal compressor

The paper presents a case study focusing on the assessment of the aerothermodynamic and rotordynamic performance to diagnose deposit accumulation on the internals of a centrifugal compressor. The case involves a four-stage gas lift centrifugal compressor powered by a 5.9 MW induction motor and utilizing a fluid coupling to regulate the compressor's rotational speed. The Huntington 4-point method was employed to evaluate the polytropic head and efficiency of the four compressor sections over a 20-month period, with pressure and temperature data sampled every 6 hours. The efficiency model was supported by the GERG-2008 equation of state, used to calculate the necessary thermodynamic properties at intermediate and endpoint states. The aerothermodynamic analysis identified a deterioration in polytropic efficiency in compressor section 3, accompanied by a pressure drop and an increase in discharge temperature. Simultaneously, the rotordynamic response was examined through various vibration plots. Although the increase in the vibration amplitudes was not significant, a notable phase shift was observed. This decline in polytropic efficiency and change in vibration patterns were attributed to severe fouling, which was confirmed during the overhaul of the HP compressor. Root cause investigations revealed the deposit as reactive, leading to the installation of an online washing system. Over a nine-month observation period post-maintenance, the compressor operation was stable with no degradation in its polytropic efficiency.

Rigid Mode Vibration Control for 250 HP Air Compressor System With Integrated Hybrid Air-Foil Magnetic Thrust Bearing (i-HFMTB)

Abstract This study aims to verify the effectiveness of the 250 HP class compressor system to which the integrated hybrid air-foil magnetic thrust bearing (i-HFMTB) proposed in (Ha et al., 2023, “Integrated Hybrid Air Foil-Magnetic Thrust Bearing (i-HFMTB) Part I: Preliminary Experimental Test for Rotordynamic Parameter Identification and Behavior With PD Control,” ASME Paper No. GT2023-102860) [1] is applied, and the vibration and instability problems of air-foil journal bearing (AFJB) occurring in the rigid mode are controlled by i-HFMTB. The compressor rotor is supported by two AFJB (journal diameter = 60 mm) and an i-HFMTB, and the length and mass of the rotor are 550 mm and 15.24 kg, respectively. i-HFMTB has a structure in which air-foil thrust bearing (AFTB) pads are inserted into eight slotted active magnetic thrust bearings (AMTB), and PD control (proportional gain: 4000; differential gain: 10) is applied. The operating area was identified through AFJB’s dynamic coefficients and rotordynamic analysis. As a result, in the experiment with the 250 HP compressor system supported only by two AFJB, sub- and super-synchronous vibrations were generated owing to the AFJB’s insufficient load capacity and damping in the rigid mode (7000 rpm) region, and this instability did not disappear even upon increasing the speed to 15,000 rpm. However, when i-HFMTB was turned on in rigid mode, it was confirmed that the sub- and super-synchronous vibrations were significantly reduced. The thrust collar tilt angle was calculated through orbit trajectory analysis of the impeller and cooling side, and it was confirmed that the tilt angle of the thrust collar was reduced during i-HFMTB operation.

Dry air compressor for car painting quality improvement

The humidity used in the painting process greatly determines the result of painting the car body. This study aims to develop a dry air compressor that can be used to overcome car paint defects. This system consists of a 2 HP compressor engine for sucking air from the atmosphere, two air collection tubes where the first tube contains air obtained from the atmosphere and the second tube contains dry air obtained from the first tube. The inside of the first tube is given a copper coil measuring 5 mm in diameter which is connected to a 120-watt cooler while the second tube is not given a copper coil. Each tube has a diameter of 50 cm and a height of 100 cm. The addition of copper coil aims to separate air from water by means of the condensation process which is the development of this study. Testing of compressor performance is done by turning on the compressor with the exhaust valve closed. After 60 minutes, the air pressure in each tube increased from 0 Psi to 89 Psi, the humidity decreased from 52 % to 38 %, and the temperature decreased from 31.6 °C to 18.2 °C. To see the effect of cooling on the air, the exhaust valves on both tubes were opened. In the first tube there is water coming out, as much as approximately 100 ml while in the second tube there is no water coming out. The water that comes out of the first tube is caused by the condensation process that separates the air from the water and due to the influence of gravity the water falls to the bottom of the tube. The dry air contained at the top of the first tube is flowed into the second tube and is ready to be used for painting the car body. The painting results show that there are no more small holes or paint defects on the paint surface

Assessment of performance degradation of a mixed flow low bypass turbofan engine through GasTurb simulation

Abstract Aero engine performance analysis is very important for engines under development as well as for engines in service for condition monitoring. Predictions of aero engine performance and ability of building the simulation model is an invaluable asset for designers, manufacturer and end-use operator. This paper presents the methodology in establishing the baseline performance of a twin spool mixed flow low bypass turbofan engine through extensive testing at engine test bench. The baseline data is used to validate a GasTurb model which is subsequently used for assessment of off-design performance and component degradation responsible for performance deterioration at various service hours. The estimated exhaust gas temperatures by the model for degraded engines are in good agreement with the measured data. The model further assesses the drop in HP compressor efficiency and shift in operating line which will be very useful for taking judicious decision for withdrawal of engines and is expected to reduce or delay withdrawals and increase the availability of engines at operating base.

Energy and exergy analysis of a novel direct-expansion ice thermal storage system based on three-fluid heat exchanger module

Direct-expansion ice thermal storage (DX-ITS) system can overcome the mismatch between cold energy supply and demand, and also exhibit the characteristics of high energy efficiency, simple pipeline and minimal installation space. However, existing DX-ITS failed to achieve simultaneous high-efficiency heat transfer in the processes of charging and discharging, thereby limiting its widespread use. This study developed a novel DX-ITS system based on three-fluid heat exchanger modules employing micro heat pipe arrays to address the proceeding issue. Temperature distribution, pressure, charging and discharging power, energy efficiency ratio, exergy efficiency and ice packing factor during the charging and discharging processes at different compressor speeds, cooling-air temperature and flow rates were experimentally studied. Results demonstrated that maximum charging power, energy efficiency ratio, exergy efficiency, ice packing factor and discharging power of proposed system using a 4 HP compressor under experimental conditions reached 5.71 kW, 2.31, 11.12 %, 82.1 % and 4.99 kW, respectively. Moreover, cooling-air temperature had a more significant effect on system performance compared with cooling-air flow rate and compressor speed. The 11.7 %, 25.9 %, 24.3 %, and 20.6 % reductions in charging power, energy efficiency ratio, exergy efficiency, and ice packing factor were observed with an increase of cooling-air temperature from 18 °C to 35.5 °C.

Fracture Analysis of Compressor Impellers in Olefin Units: Numerical and Metallurgical Approach

This paper presents a failure analysis conducted in 7175 aluminum alloy compressor impellers used in olefin units which operate at 34500 rpm to compress gas in the process. Some characterizations such as chemical composition, microstructure, and hardness tests were conducted to obtain a detailed evaluation of the base alloy. Furthermore, a finite element method and a 3D point cloud data technique have used to determine critical stress points on the surface of impellers. The finite element result showed the root of blades has significant stress concentration. Moreover, the formed cyclic tension has led to a fatigue phenomenon in the root of the blade, so near this location, the local strain accumulation was visible in 3D points cloud data. The fractography results showed that the mode of crack progression and the fractured surface would change by changing the stress mode. In addition, CFD modeling for investigating the effect of flow hydrodynamics on the HP and LP compressor blades is analyzed. The results revealed that the maximum pressure of gas stream for the rotor speed of 34500 had taken place in the area of a blade that already breakdown took place, and the changes of pressure, stress, and temperature gradients of flow in the HP compressor were significantly higher than the LP compressor.

Energy management of precooling process for green cabbages

Cold storage is one of the most widely used and effective processes to preserve shelf-life harvested agricultural products during long periods. Research to date has not yet determined the energy management of pre-cooling methods of green cabbage. This study seeks to investigate the cooling performance of the cold storage, keeping green cabbages with good quality and to report different pre-cooling strategies. The cold storage specifications included 15 HP compressor with a voltage of 380 V, a temperature range of -50 to 50°C, and R22 refrigerant. The mass of green cabbage was examined with three values of 30, 40, and 50 kg. Moreover, the pre-cooling strategies of the green cabbages were divided into four scenarios including the parallel pattern in the front zone, staggered pattern in the front zone, parallel pattern in the back zone, and staggered pattern in the back zone. The experimental results revealed that the coefficient of performance (henceforth COP) was significantly affected by the mass of the cabbage and cooling zone of the cold storage. While the pattern in case of 30 kg cabbage precooling had a slight effect on cooling performance due to the lower density arrangement and heat extraction. The highest COP appeared at the 30 kg cabbage precooling with the strategy of staggered pattern in the front zone. The COP value was 2.61.

Numerical Characterisation of a HP Compressor Stage Equipped with a Closed Shrouded Stator Cavity

Abstract In axial compressors, shrouded stator cavity flows are responsible for performance degradation due to their interaction with the power stream. The present paper aims at exploring the possibility of employing a single stage high pressure axial compressor as a test vehicle for cavity flows investigations. In a first step, the robustness of the adopted RANS approach is tested against experimental data on the closed-cavity baseline configuration (i.e. no downstream-to-upstream recirculation). In a second phase, the effect of different hub cavities layouts of different levels of realism is numerically investigated. The focus is set on the representativeness of a closed cavity configuration with injection. The cavity flow topology and impact on the overall performance are considered in the analysis. At its final extent, this paper provides numerical and experimental guidelines for the robust assessment of cavity flows topology and performance effects.

Specification of the 2nd cryogenic plant for RAON

RAON is a rare isotope beam facility being built at Daejeon, South Korea. The RAON consists of three linear accelerators, SCL1 (1st SuperConducting LINAC), SCL2, and SCL3. Each LINAC has its own cryogenic plant. The cryogenic plant for SCL2 will provide the cooling for cryomodules, low temperature SC magnets, high temperature SC magnets, and a cryogenic distribution system. This paper describes the specification of the plant including cooling capacity, steady state and transient operation modes, and cooling strategies. In order to reduce CAPEX with the specification, two suppliers will consider no liquid nitrogen pre-cooling, one integrated cold box, and one back-up HP compressor. The detail design of the plant will be started at the end of this year.

Experimental investigation on a novel integrated system of vapor compression and pump-driven two phase loop for energy saving in data centers cooling

A novel integrated system of vapor compression and pump-driven two phase loop for energy saving in data centers cooling is presented in this paper. In the new system, the vapor compression mode works at the hot outdoor temperature and the pump-driven mode operates at the cold outdoor temperature. An experimental bench was constructed using a 3 HP compressor and a 1 HP compressor in the integrated system, respectively. The results show that, the new system has a better performance for application in data centers, the maximum cooling EER of the integrated system can reach to 29.71. The most suitable outdoor temperature for switching the modes was also obtained from the experiment. It is recommended to design the integrated system based on the cooling performance of the pump-driven two phase loop.

1/4 마력급 압축기의 성능 개선을 위한 SPIM 회전자의 충진율에 관한 연구

This paper discusses to the capability improvement of the 1/4 HP compressor. And, for efficiency improvement of the single phase induction motor, this paper has proposed a casting method to improving the fill factor of the rotor of the single phase induction motor. First, by using FEM, it was analyzed the magnetic flux distribution and the fill factor to the SPIM rotor by the conventional method and the proposed method. And, based on the FEM analysis results, SPIMs are manufactured by the each casting process. Through experiments using dynamometer, they were compared and measured to their efficiencies. In addition, through experiments using Calorimeter, we have analyzed the refrigerating capacity of the compressor of which they were applied. Based on the results of the previous two experiments, they are to verify the validity of the proposed method.

Numerical Investigation of Conjugate Heat Transfer and Flow Characteristics on Shrouds in a Gas Engine HP Compressor Blades

This investigation is on the numerical simulation of Conjugate Heat Transfer and efficient compression of air density from the upstream to the HP compressor section of a Gas Engine Rotor for various configurations of geometry and position of shrouds considering Ti-6Al-4V as blade material. The shrouds provide high contact region for the Conduction and Structural Integrity as it is more aerodynamic and feasible when compared to unshrouded blades, hence calling for the optimum positioning of shrouds. Three positions of shrouds at tip, 3/4th and mid way along the blade height of Axial HP compressor vanes are considered with flat and tapered geometry for the analysis. The distribution of Static Pressure, Turbulence Intensity and their impacts on temperature distribution, local and overall heat transfer coefficient were studied for various design configurations using Computational Fluid Dynamics and an efficient model out of the above mentioned configurations was identified which provides comparatively high density of air, high Overall Heat Transfer Co-efficient and hence, efficient Compressor Cooling.

Performance Analysis of an Aircraft Gas Turbine Engine using Particle Swarm Optimization

A turbo fan engine performance analysis and the optimization using particle swarm optimization(PSO) algorithm have been conducted to investigate the effects of major performance design parameters of an aircraft gas turbine engine. The FJ44-2C turbofan engine, which is widely used in the small business jet, CJ2 has been selected as the basic model. The design parameters consists of the bypass ratio, burner exit temperature, HP compressor ratio, fan inlet mass flow, and nozzle cooling air ratio. The sensitivity analysis of the parameters has been evaluated and the optimization of the parameters has been performed to achieve high net thrust or low specific fuel consumption.

Thermo‐economic Optimization of Gas Turbine Power Plant with Details in Intercooler

AbstractIn this paper a gas turbine power plant with intercooler is modeled and optimized. The intercooler is modeled in details using the ε − NTU method. Air compressor pressure ratio, compressor isentropic efficiency, gas turbine isentropic efficiency, turbine inlet temperature, cooling capacity of the absorption chiller, recuperator effectiveness as well as eight parameters for configuration of the intercooler are selected as design variables. Multi‐objective genetic algorithm is applied to optimize the total cost rate and total cycle efficiency simultaneously. Two plants including an intercooler and with/without air preheater are studied separately. It is observed that the air compressor pressure ratio in the HP compressor is higher than the LP compressor in both cases and its differences are higher for a plant without an air preheater. Actually the air compressor pressure ratio is found to be about 8.5% lower than the ideal value and 9.5% higher than the ideal value in the LP compressor and HP compressor, respectively, in the case with an air preheater. Moreover, a correlation for intercooler pressure drop in terms of its effectiveness was derived in the optimum situation for each case. © 2013 Wiley Periodicals, Inc. Heat Trans Asian Res, 42(8): 704–723, 2013; Published online in Wiley Online Library (wileyonlinelibrary.com/journal/htj). DOI 10.1002/htj.21051

냉기 강제순환형 공랭식 쇼케이스 성능 해석

본 연구에서는 식료품의 진열과 보관에 사용되며 전시효과가 우수한 냉기 강제순환식 쇼케이스의 성능을 예측하는 프로그램을 개발하였다. 압축기의 성능해석에는 제조사에서 제공한 성능선도를 사용하였고 모세관 내 압력손실은 균질유동 모델을 사용하여 계산하였다. 증발기와 응축기는 미소체적으로 구분하여 에너지 균형을 고려하였고 관내측과 공기측 열전달계수는 적절한 상관식으로부터 구하였다. 압축기로 3/4 마력급 왕복동식 2개를 사용하고, 팽창장치로는 내경 1.6 mm의 모세관을, 응축기와 증발기로는 상호 공유형태의 핀-튜브 열교환기를 적용한 쇼케이스 시제품에 대해 성능시험을 수행하고 시험결과와 비교했을 때, 본 프로그램은 시제품의 증발 온도와 응축 온도를 적절히 예측함을 확인하였다. In this study, a simulation program was developed, which predicts the performance of cold-air forced circulation type air cooled showcase. The showcase has an excellent display effect in addition to preserving the grocery. In the program, the compressor was analyzed using performance data supplied by the manufacturer and the capillary tube pressure drop was analyzed using a homogeneous model. The evaporator and condenser were analyzed by dividing the heat exchangers into small elements, where energy balance and appropriate heat transfer correlations were used. A showcase model with two 3/4 HP compressors, capillary tubes of 1.6 mm inner diameter, a fin-and-tube evaporator and condenser was tested, and the results are compared with the predicted values. It is shown that both evaporation and condensation temperatures are adequately predicted by the program.

An Educational Software Suite for Teaching Design Strategies for Multistage Axial Flow Compressors

The T-AXI turbomachinery design system, an axisymmetric methodology recently developed with an educational purpose, has shown great capabilities in the redesign of existing axial flow gas turbine components. Different turbomachines, single or multistage configurations, have been already reproduced with excellent overall performance results: examples are the NASA/GE E3 HP compressor and LP turbine. In this paper, the authors present a detailed analysis of the results of a “case-study” application of the code as a complementary tool to be used during a turbomachinery design course. The NASA/GE E3 HP compressor has been chosen as the test case. Starting from the data available in open literature the different steps of the redesign have been reported: from the flowpath generation through the thermodynamic properties distributions to the overall turbomachine performance analysis. Particular attention has been given to some critical aero design parameters. The links to some interesting and useful literature sources are reported. The free-vortex, the only vortex law included in the first version of the code has been used for a first EEE compressor redesign. Different design vortex methodologies have been implemented in the new release of the code and their effects on the angular momentum are reported. The corresponding geometries can also be interfaced to a mesh generator and then the turbomachinery configurations analyzed by a 3D Navier-Stokes solver. In this way the flow field can be carefully analyzed and the fluid-dynamic physics better understood. With the above software structure the student has the opportunity to test the effects of different design strategies on the turbomachinery performance and to understand the need of a hierarchy of tools that give complete information for the multistage turbomachinery design. Finally, in the last section of the paper, the authors present how a project such as T-AXI, developed from their research activity in turbomachinery, numerical methods and CFD, can be included in the education tool CompEdu.

Optimization of recirculation operating in liquefied natural gas receiving terminal

In a LNG (liquefied natural gas) receiving terminal, the recirculation flow rate which is an important process variable determines the temperature of the unloading pipe and affects the amount of BOG (boiled-off gas) flowing into the storage tank. Therefore the operation of the BOG compressor and HP compressor which handles the BOG in the storage tank affects the recirculation flow rate. The recirculation flow rate makes a trade-off between the operating costs of the BOG/HP (high pressure) compressor and the recirculation pump which sends the recirculation flow. This study was able to achieve the optimal recirculation flow rate taking into consideration the operating costs of the BOG/HP compressor and pump. Also the BOG handling method is different depending on the amount of send-out because the BOG is condensed by the send-out LNG. Therefore, it is proposed that optimized recirculation operations depend on the amount of LNG send-out. In order to predict the amount of BOG dependent on the recirculation flow rates, this study conducted a dynamic simulation of the unloading process in a LNG receiving terminal. A dynamic model that is able to reflect the influence of the valve operation was developed so that the change of the inner state that cannot be measured by sensors is predicted. Steady-state modeling and main pipeline modeling, branch pipeline modeling and boundary stream modeling were done using HYSYS Dynamics. Simulation of the developed dynamic model was done under the operating scenario based on normal operating procedures. Using the dynamic simulation, the operating costs of the BOG/HP compressor and pump were obtained through 29 recirculation flow rates. The optimal recirculation flow rate was obtained depending on the LNG sent-out rate. This study proposes optimized recirculation operations which control the recirculation flow rates and take into account the LNG send-out rate. The proposed method was compared to an existing method, and the cost-saving benefits were confirmed.

The Effect of Leading-Edge Geometry on Wake Interactions in Compressors

The effect of leading-edge geometry on the wake/boundary-layer interaction was studied in a low-speed single-stage HP compressor. Both a 3:1 elliptic and a circular leading edge were tested on a controlled diffusion aerofoil stator blade. Experiments were undertaken on the stator suction surface; these included hotwire boundary-layer traverses, surface hotfilm measurements, and high resolution leading-edge pressure measurements. Steady computational fluid dynamics (CFD) predictions were also performed to aid the interpretation of the results. The two leading-edge shapes gave rise to significantly different flows. For a blade with an elliptic leading edge (Blade A), the leading-edge boundary layer remained attached and laminar in the absence of wakes. The wake presence led to the formation of a thickened laminar boundary layer in which turbulent disturbances were observed to form. Measurements of the trailing-edge boundary layer indicated that the wake/leading-edge interaction for Blade A raised the suction-surface loss by 20%. For a blade with a circular leading edge (Blade B), the leading-edge boundary-layer exhibited a separation bubble, which was observed to reattach laminar in the absence of wakes. The presence of the wake moved the separation position forward while inducing a turbulent reattachment upstream of the leading-edge time-average reattachment position. This produced a region of very high momentum thickness at the leading edge. The suction-surface loss was found to be 38% higher for Blade B than for Blade A. Wake traverses downstream of the blades were used to determine the total profile loss of each blade. The profile loss of Blade B was measured to be 32% higher than that of Blade A.

Dynamics of Multistage Bladed Disks Systems

This paper presents a new and original method for dynamical analysis of multistage cyclic structures such as turbomachinery compressors or turbines. Each stage is modeled cyclically by its elementary sector and the interstage coupling is achieved through a cyclic recombination of the interface degrees of freedom. This method is quite simple to set up; it allows us to handle the finite element models of each stage’s sector directly and, as in classical cyclic symmetry analysis, to study the nodal diameter problems separately. The method is first validated on a simple case study which shows good agreements with a complete 360 deg reference calculation. An industrial example involving two HP compressor stages is then presented. Then the forced response application is presented in which synchronous engine order type excitations are considered.

Measurement and CFD Prediction of the Flow Within an HP Compressor Drive Cone

In some gas turbine aeroengines, the HP compressor is driven by the H.P. turbine through a conical shaft or drive cone. This drive cone is enclosed by a stationary surface that forms the supporting material for the combustion chambers. Air used to cool the turbine blades is directed into the space around the drive cone, and a major concern to an engine designer is the temperature rise in this air due to frictional dissipation and heat transfer. This paper presents results from a combined experimental and CFD investigation into the flow within an engine representative HP compressor drive cone cavity. The experimental results show similarities in flow structure to that found in classic rotor-stator systems. Both 2-D and 3-D CFD simulations were carried out using the FLUENT/UNS code. The 3-D model which included the actual compressor blade tip clearance gave the best agreement with the experimental data. However, the computational resource required to run the 3-D model limits its practical use. The 2-D CFD model, however, was found to give good agreement with experiment, providing care was exercised in selecting an appropriate value of initial tangential velocity.