Upstream Pump Research Articles

Multistage Micropump System towards Vacuum Pressure

Fraunhofer EMFT’s research and manufacturing portfolio includes piezoelectrically actuated silicon micro diaphragm pumps with passive flap valves. Research and development in the field of microfluidics have been dedicated for many years to the use of micropumps for generating positive and negative pressures, as well as delivering various media. However, for some applications, only small amounts of fluid need to be pumped, compressed, or evacuated, and until now, only macroscopic pumps with high power consumption have been able to achieve the necessary flow rate and pressure, especially for compressible media such as air. To address these requirements, one potential approach is to use a multistage of high-performing micropumps optimized to negative pressure. In this paper, we present several possible ways to cascade piezoelectric silicon micropumps with passive flap valves to achieve these stringent requirements. Initially, simulations are conducted to generate negative pressures with different cascading methods. The first multistage option assumes pressure equalization over the piezo-actuator by the upstream pump, while for the second case, the actuator diaphragm operates against atmospheric pressure. Subsequently, measurement results for the generation of negative gas pressures down to −82.1 kPa relative to atmospheric pressure (19.2 kPa absolute) with a multistage of three micropumps are presented. This research enables further miniaturization of many applications with high-performance requirements for micropumps, achievable with these multistage systems.

Influence of Pump Rotation Speed on Hydrodynamic Performance and Stator Blade Surface Pressure Pulsation in Torque Converter

Abstract An experimental investigation was performed to characterize the influence of pump rotation speed on the hydrodynamic performance and the associated unsteady pressure on the stator blade pressure-surface in a torque converter. High-resolution miniature transducers were used to obtain the signature of the pressure pulsation at specific surface locations. Results show that the increase of the pump rotation speed can enhance the torque capacity of the stator, leading to a higher torque ratio in the low speed ratio range and an improvement of the highest transmission efficiency. The efficiency increase rate starts to reduce at approximately SR = 0.4, corresponding to where the stator capacity reaches the maximum and exhibits a uniform distribution of the pressure pulsation intensity. The spectral decomposition of the pulsating pressure reveals the existence of two dominating frequencies, which corresponds to the upstream pump turbine interaction and the downstream pump blade passing. Higher pump speeds enhance the pump turbine interaction and results in a more regular pressure pulsation, improving the hydrodynamic performance of the torque converter.

Drainage Management Problems Evaluation: Case Study Baloza and EL-Farama Drains, North Sinai, Egypt

Drainage management activities aim at maintaining the performance of drainage networks by assessing the major drainage management problems regarding sedimentation, bank erosion, vegetation, water quality, and biodiversity, to find appropriate solutions for channel improvement in order to increase agricultural productivity and maintain agricultural land and the surrounding environment. In this research, we evaluate the drainage management problems to the surface drains Baloza and EL-Farama in the cultivated Tina Plain region (21,000 hectares) North Sinai, Egypt to provide an accurate data to help decision-makers to know the status of maintenance of the watercourses and the need for improvement. For this, Intensive field investigations were carried out regarding a hydrographic survey of the actual drains cross-section using total station and aqua sounder devices, visual stream bank erosion survey, and vegetation survey. In addition, monthly water samples from the drainage water were treated and analyzed for physical and chemical, bacteriological related indices. The results showed, the studied drains suffer from sedimentation, vegetation infection, and bank erosion in some reaches and need remedy. Estimated sedimentation in EL-Farama Drain was 34369 m3/year and in Baloza Drain 29153 m3/year; bank slope failures upstream and downstream pump stations were recorded; the average weed infection ratio for both drains was 30%. The results of water quality parameters showed acceptable concentrations for BOD, DO, NO3, and total coliform according to Egypt decree, 92/2013 for the protection of the Nile River and its waterways from pollution, except TDS (more than 10,000 mg/L). The drainage water was classified as high saline and it was unacceptable for irrigation. Therefore, the author recommends to remove sedimentation and vegetation every 2 years by mechanical methods, applying gabions lining to prevent bank erosion, and treating drainage water using wetland system and utilizing the treated wastewater in fish farming.

Capillary pumping independent of the liquid surface energy and viscosity

Capillary pumping is an attractive means of liquid actuation because it is a passive mechanism, i.e., it does not rely on an external energy supply during operation. The capillary flow rate generally depends on the liquid sample viscosity and surface energy. This poses a problem for capillary-driven systems that rely on a predictable flow rate and for which the sample viscosity or surface energy are not precisely known. Here, we introduce the capillary pumping of sample liquids with a flow rate that is constant in time and independent of the sample viscosity and sample surface energy. These features are enabled by a design in which a well-characterized pump liquid is capillarily imbibed into the downstream section of the pump and thereby pulls the unknown sample liquid into the upstream pump section. The downstream pump geometry is designed to exert a Laplace pressure and fluidic resistance that are substantially larger than those exerted by the upstream pump geometry on the sample liquid. Hence, the influence of the unknown sample liquid on the flow rate is negligible. We experimentally tested pumps of the new design with a variety of sample liquids, including water, different samples of whole blood, different samples of urine, isopropanol, mineral oil, and glycerol. The capillary filling speeds of these liquids vary by more than a factor 1000 when imbibed to a standard constant cross-section glass capillary. In our new pump design, 20 filling tests involving these liquid samples with vastly different properties resulted in a constant volumetric flow rate in the range of 20.96–24.76 μL/min. We expect this novel capillary design to have immediate applications in lab-on-a-chip systems and diagnostic devices.

Theoretical analysis and modeling of flow instability in a mini-channel evaporator

Pressure drop oscillations in micro/mini-channel evaporators and corresponding flow instabilities, temperature fluctuations have received copious of investigations during the last decade. This paper presents a transient lumped model and theoretical analysis for the pressure drop oscillation in a mini-channel evaporator. Based on the model, the effects of saturation temperature, heat and mass flux on the oscillation are investigated. Experimental studies of ammonia and water flow boiling instabilities are conducted. The mini-channel evaporator consists of 4 parallel 1×1.1mm channels with a uniformly heated length of 250mm. A nonlinear system stability analysis is presented. Apart from upstream compressibility, the inlet sub-cooling degree has a significant effect on the pressure drop oscillation. A maximum allowable inlet sub-cooling degree causing no pressure drop oscillation is proposed. The oscillation period is comprehensively studied, and it is found that the upstream compressible volume required sustaining the oscillation decreases with channel length/diameter ratio dramatically. Despite this, the internal compressibility of the long channel is insufficient to sustain the pressure drop oscillation. In addition, the mass flow rate of the upstream pump can greatly affect the oscillation and the flow boiling system may show different behaviors due to the variation of upstream mass flow rate.

The IAGOS-core greenhouse gas package: a measurement system for continuous airborne observations of CO2, CH4, H2O and CO

Within the framework of IAGOS-ERI (In-service Aircraft for a Global Observing System – European Research Infrastructure), a cavity ring-down spectroscopy (CRDS)-based measurement system for the autonomous measurement of the greenhouse gases (GHGs) CO2 and CH4, as well as CO and water vapour was designed, tested and qualified for deployment on commercial airliners. The design meets requirements regarding physical dimensions (size, weight), performance (long-term stability, low maintenance, robustness, full automation) and safety issues (fire-prevention regulations). The system uses components of a commercially available CRDS instrument (G2401-m, Picarro Inc.) mounted into a frame suitable for integration in the avionics bay of the Airbus A330 and A340 series. To enable robust and automated operation of the IAGOS-core GHG package over 6-month deployment periods, numerous technical issues had to be addressed. An inlet system was designed to eliminate sampling of larger aerosols, ice particles and water droplets, and to provide additional positive ram-pressure to ensure operation throughout an aircraft altitude operating range up to 12.5 km without an upstream sampling pump. Furthermore, no sample drying is required as the simultaneously measured water vapour mole fraction is used to correct for dilution and spectroscopic effects. This also enables measurements of water vapour throughout the atmosphere. To allow for trace gas measurements to be fully traceable to World Meteorological Organization scales, a two-standard calibration system has been designed and tested, which periodically provides calibration gas to the instrument during flight and on ground for each 6-month deployment period. The first of the IAGOS-core GHG packages is scheduled for integration in 2015. The aim is to have five systems operational within 4 yr, providing regular, long-term GHG observations covering major parts of the globe. This paper presents results from recent test flights and laboratory tests that document the performance for CO2, CH4, CO and water vapour measurements.

Experimental study of cavitation phenomenon in a centrifugal blood pump induced by the failure of inlet cannula

Cavitation of centrifugal blood pump is a serious problem accompany with the blocking failure of short inlet cannula. However, hardly any work has been seen in published literature on this complex cavitation phenomenon caused by the coupling effect of inlet cannula blocking and pumps suction. Even for cavitation studies on ordinary centrifugal pumps, similar researches on this issue are rare. In this paper, the roles of throttling, rotation speed and fluid viscosity on bubble inception and intensity in a centrifugal blood pump are studied, on the basis of experimental observations. An adjustable throttle valve installed just upstream blood pump inlet is used to simulate the throttling effect of the narrowed inlet cannula. The rotation speed is adjusted from 2 600 r/min to 3 200 r/min. Glycerin water solutions are used to investigate the influences of kinetic viscosity. Bubbles are recorded with a high-speed video camera. Direct observation shows that different from cavitation in industrial centrifugal pumps, gas nuclei appears at the nearby of vane leading edges while throttling is light, then moves upstream to the joint position of inlet pipe and pump with the closing of the valve. It’s found that the critical inlet pressure, obtained when bubbles are first observed, decreases linearly with viscosity and the slope is independent with rotation speeds; the critical inlet pressure and the inlet extreme pressure which is obtained when the throttle valve is nearly closed, fall linearly with rotation speed respectively and the relative pressure between them is independent with rotation speed and fluid viscosity. This paper studies experimentally on cavitation in centrifugal blood pump that caused by the failure of assembled short inlet cannula, which may beneficial the design of centrifugal blood pump with inlet cannula.

Determination of the critical time of canal storage capacity controlled by cross pump stations “Case Study: Egypt, El-Salam Canal”

El-Salam Pump Stations (1) and (2) are located at 22.1km and 54.3km respectively at El-Salam Canal. When El-Salam Pump Station (1) is in operation, and switching off El-Salam Pump Station (2), water level rises upstream El-Salam Pump Station (2). Water level overtops El-Salam Pump Station (2) and banks upstream it. Flooding then takes place as Wadi El Noqra Canal, Egypt. This necessitates discharging the excess water to protect the pump station and the canal from water flooding when the electricity is shut down. The hydrodynamic simulation of El-Salam Canal determinates the critical time for storage capacity according to location and type of emergency spillways through the numerical model to prevent water overtopping upstream pump stations. Determination of the critical time of storage capacity is considered as a new parameter in case of the hydraulic design of the canal controlled by cross pump stations.

A self-priming, roller-free, miniature, peristaltic pump operable with a single, reciprocating actuator

We present a design for a miniature self-priming peristaltic pump actuated with a single linear actuator, and which can be manufactured using conventional materials and methods. The pump is tolerant of bubbles and particles and can pump liquids, foams, and gases. We explore designs actuated by a motor (in depth) and a shape memory alloy (briefly); and briefly present a manually actuated version. The pump consists of a Delrin acetal plastic body with two integrated valves, a flexible silicone tube, and an actuator. Pumping is achieved as the forward motion of the actuator first closes the upstream valve, and then compresses a section of the tube. The increased internal pressure opens a downstream burst valve to expel the fluid. Reduced pressure in the pump tube allows the downstream valve to close, and removal of actuator force allows the upstream valve and pump tube to open, refilling the pump. The motor actuated design offers a linear dependence of flow rate on voltage in the range of 1.75–3 V. Flow rate decreases from 780 μl/min with increasing back pressure up to the maximum back pressure of 48 kPa. At 3 V and minimum back pressure, the pump consumes 90 mW. The shape memory alloy actuated design offers a 5-fold size and 4-fold weight reduction over the motor design, higher maximum back pressure, and substantial insensitivity of flow rate to back pressure at the cost of lower power efficiency and flow rate. The manually actuated version is simpler and appropriate for applications unconstrained by actuation distance.

Vibrational dynamics of the linear and bent isomers of HF–N 2O trapped in 0.4 K helium nanodroplets

Infrared (IR)–IR double resonance spectroscopy is used to probe the isomerization dynamics of helium solvated HF–N 2O following the vibrational excitation of one of two stable isomers on the intermolecular potential energy landscape. An upstream pump laser excites the H–F stretching fundamental of either the linear ONN–HF or the bent NNO–HF isomer, while a downstream probe laser is scanned through the bands of both isomers to test for photo-induced isomerization. Vibrational excitation of the H–F stretch mode leads to the isomerization of a fraction of the upstream population, regardless of the identity of the pumped isomer. The measured isomer interconversion is consistent with vibrational predissociation followed by geminate recombination. A fraction of the upstream population is unaccounted for by the downstream probe. We propose that a fraction of the missing population is due to the mismatch in the timescales of complex recombination and pump, probe events.

Periodic Velocity Measurements in a Wide and Large Radius Ratio Automotive Torque Converter at the Pump∕Turbine Interface

The unsteady flow field due to blade passing at the pump∕turbine interface of a torque converter was studied. The current geometry is wide and has a large outer to inner radius ratio. A laser velocimeter was used to measure the periodic velocity components at four operating conditions determined by the speed ratios between the turbine and pump of 0.065 (near stall), 0.600, 0.800, and 0.875 (coupling point). The flow fields at the pump exit and turbine inlet planes were visualized and are presented. Using instantaneous pump and turbine blade positions with the velocity data, animations (“slow-motion movies”) are generated to effectively visualize and understand the unsteady behavior. The turbine inlet flow was markedly periodic due to the exiting jet∕wake from the upstream pump passage; however, the pump exit flow field showed little dependence on the turbine blade positions. The highest unsteadiness was seen for the highest speed ratios. Four “shots” from the sequences of one cycle for all speed ratios and each plane are presented herein. The results are also compared to unsteady results for a previously examined torque converter with a small radius ratio to determine the effect of parametric geometric changes on the flow field. Generally, the unsteady velocity fields show no significant difference for the two geometries—the trends are the same.

Laser Velocimeter Measurements in the Turbine of an Automotive Torque Converter: Part II—Unsteady Measurements

The unsteady velocity field found in the turbine of an automotive torque converter was measured using laser velocimetry. Velocities in the inlet, quarter, mild, and exit planes of the turbine were investigated at two significantly different turbine/pump rotational speed ratios: 0.065 and 0.800. A data organization method was developed to visualize the three-dimensional, periodic unsteady velocity field in the rotating frame. For this method, the acquired data are assumed to be periodic at synchronous and blade interaction frequencies. Two shaft encoders were employed to obtain the instantaneous angular position of the torque converter pump and turbine at the instant of laser velocimeter data acquisition. By proper “registration” of the velocity data, visualizing the transient interaction effects between the turbine, pump, and stator was possible. Results showed strong cyclic velocity fluctuations in the turbine inlet plane as a function of the relative turbine-pump position. These fluctuations are due to the passing of upstream pump blades by the slower rotating turbine blades. Typical fluctuations in the through flow velocity were 3.6 m/s. Quarter and midplane velocity fluctuations were seen to be lower; typical values were 1.5 m/s and 0.8 m/s, respectively. The flow field in the turbine exit plane was seen to be relatively steady with negligible fluctuations of less than 0.03 m/s. From the velocity data, the fluctuations of turbine performance parameters such as flow inlet angles, root-mean-square unsteadiness, and output torque per blade passage were calculated. Incidence angles were seen to vary by 3 and 6 deg for the 0.800 and 0.065 speed ratios, respectively, while the exit angles remained steady. The turbine output torque per blade passage fluctuated by 0.05 Nm for the 0.800 speed ratio and 0.13 Nm for the 0.065 speed ratio.

A model of insulin delivery by a controlled release micropump.

A model has been developed to describe the delivery of insulin from a controlled release micropump (CRM). Basal delivery was provided by diffusion due to a concentration difference driving force across the CRM. This was modelled by considering the CRM to be a series of one-dimensional steady-state diffusion resistances. This delivery model was used to size prototypes and identify the piston, foam and the pump outlet as the controlling resistances to basal insulin transport. Augmented delivery by the CRM was achieved by repeated compression of a foam disk by a mild steel piston which was driven by a solenoid (tested voltage range 0-173 V DC; 5 msec "on" time; frequency 20-40 min-1). The increased delivery was attributed to the combination of mixing inside the pump barrel and displacement of barrel contents into the downstream reservoir. This action was approximated by a three-compartment model, which considered the CRM to consist of a well-mixed upstream reservoir and pump barrel (with a downstream reservoir) separated by two resistances: a constant upstream membrane resistance, (KmAm)-1, and a variable downstream mixing rate resistance, (Qd)-1. A least squares fit of the model to experimental data showed Qd to increase with the cube of the force on the piston and linearly with the compression frequency. In agreement with experimental results, the model predicted the upstream membrane to be rate controlling only at augmented pump resistances close to the value (KmAm)-1. These models were used to design an improved prototype (VIII) which is now being evaluated in vivo in pancreatectomized dogs for its efficacy in restoring and sustaining normoglycemia.