skip to main content
US FlagAn official website of the United States government
dot gov icon
Official websites use .gov
A .gov website belongs to an official government organization in the United States.
https lock icon
Secure .gov websites use HTTPS
A lock ( lock ) or https:// means you've safely connected to the .gov website. Share sensitive information only on official, secure websites.

Explore Research Products in the PAR
It may take a few hours for recently added research products to appear in PAR search results.


Title: Experimental Study of Dynamic Icing Process on a Pitot Probe Model
An experimental study was conducted to characterize the dynamic ice accretion process over the surface of a typical aeronautic Pitot probe model under different icing conditions. The experimental study was conducted in the Icing Research Tunnel available at Iowa State University. While a high-speed imaging system was used to record the dynamic ice accretion process, a three-dimensional (3D) scanning system was also used to measure the 3D shapes of the ice layers accreted on the test model. While opaque and grainy ice structures were found to accrete mainly along the wedge-shaped lip of the front port and over the front surface of the probe holder under a dry rime icing condition, much more complicated ice structures with transparent and glazy appearance were observed to cover almost entire surface of the Pitot probe under a wet glaze icing condition. While a flower-like ice structure was found to grow rapidly along the front port lip, multiple irregular-shaped ice structures accreted over the probe holder under a mixed icing condition. The characteristics of the icing process under different icing conditions were compared in terms of 3D shapes of the ice structures, the profiles of the accreted ice layers, the ice blockage to the front port, and the total ice mass on the Pitot probe model. The acquired ice accretion images were correlated with the 3D ice shape measurements to elucidate the underlying icing physics.  more » « less
Award ID(s):
1916380
PAR ID:
10428911
Author(s) / Creator(s):
; ; ;
Date Published:
Journal Name:
Journal of Thermophysics and Heat Transfer
Volume:
37
Issue:
3
ISSN:
0887-8722
Page Range / eLocation ID:
632 to 643
Format(s):
Medium: X
Sponsoring Org:
National Science Foundation
More Like this
  1. ; ; ; (, Journal of Thermophysics and Heat Transfer)
    An experimental campaign was conducted to study dynamic ice accretion on rotating aeroengine fan blades and evaluate the icing-induced performance degradation to the fan rotor. The experiments were performed in an icing research tunnel with a scaled spinner-fan model exposed to typical dry rime and wet glaze icing conditions. Although the accreted ice layers were found to conform well with the shapes of the fan blades under the rime icing condition, the performance of the fan rotor was found to degrade substantially due to the much rougher blade surfaces, causing up to 60% reduction in the pressure increment after 360 s of the rime icing experiment. More complicated, needlelike icicles were found to grow rapidly over the rotating spinner and fan blades under the glaze icing condition due to the combined effects of the aerodynamic forces and the centrifugal forces associated with the rotation motion. The irregular-shaped glaze ice structures were found to induce tremendous detrimental effects on the fan rotor, making the airflow depressurized, instead of pressurized, after passing the iced fan rotor. The iced spinner-fan model was always found to consume more power, regardless of rime or glaze ice structures accreted on the fan blades. 
    more » « less
  2. ; ; (, AIAA Journal)
    An experimental study was conducted to examine the dynamic ice accretion process upon the impingement of microsized, airborne ice particles/crystals onto a heated test surface pertinent to aeroengine icing phenomena. The experimental study was conducted in a specially designed ice crystal icing test facility to generate and inject microsized ice particles into a frozen-cold airflow. The microsized ice particles were forced to impinge onto a heated test plate with controllable surface temperatures. Upon impingement of the ice particles onto the heated test surface, the dynamic ice accretion process was found to take place over the heated surface in three distinct stages: 1) an ice-melting stage at the beginning, followed by 2) an ice/water mixture formation stage, and then 3) a water refreezing stage, causing the formation of a solid ice layer accreted on the heated test surface eventually. After impinging onto the test plate, while small ice particles with spheric shapes were found to be more ready to bounce off from the test surface, large, nonspheric-shaped ice particles experienced a catastrophic fragmentation process and break up into smaller pieces with noticeable impingement residues remaining on the test surface. The formation of a liquid water film layer on the test surface due to the melting of the impinged ice particles was found to be very beneficial to make more impinged ice particles stay sticking on the test surface, resulting in a rapid growth of the water/ice layer accreted on the heated test surface. A comprehensive theoretical analysis was also performed to examine the unsteady heat transfer characteristics during the dynamic ice accretion process. The theoretic predictions of the collection efficiency of the impinged ice particles on the heated test surface and the temperature variations of the water layer at the initial ice-melting stage were found to agree well with the experimental measurement results. 
    more » « less
  3. ; (, Proceedings of the National Academy of Sciences)
    A field campaign was carried out to investigate ice accretion features on large turbine blades (50 m in length) and to assess power output losses of utility-scale wind turbines induced by ice accretion. After a 30-h icing incident, a high-resolution digital camera carried by an unmanned aircraft system was used to capture photographs of iced turbine blades. Based on the obtained pictures of the frozen blades, the ice layer thickness accreted along the blades’ leading edges was determined quantitatively. While ice was found to accumulate over whole blade spans, outboard blades had more ice structures, with ice layers reaching up to 0.3 m thick toward the blade tips. With the turbine operating data provided by the turbines’ supervisory control and data acquisition systems, icing-induced power output losses were investigated systematically. Despite the high wind, frozen turbines were discovered to rotate substantially slower and even shut down from time to time, resulting in up to 80% of icing-induced turbine power losses during the icing event. The research presented here is a comprehensive field campaign to characterize ice accretion features on full-scaled turbine blades and systematically analyze detrimental impacts of ice accumulation on the power generation of utility-scale wind turbines. The research findings are very useful in bridging the gaps between fundamental icing physics research carried out in highly idealized laboratory settings and the realistic icing phenomena observed on utility-scale wind turbines operating in harsh natural icing conditions. 
    more » « less
  4. ; ; ; (, AIAA AVIATION 2023 Forum)
    The accretion of ice on the surface of a wind turbine blade causes a drastic reduction in the aerodynamic performance and as a result, the power output, in addition to posing a safety hazard. To quantify this phenomenon, an experimental study was conducted in the Iowa State University Icing Research Tunnel (ISU-IRT) to understand the dynamic ice accretion process and resultant aerodynamic performance degradation specifically experienced by offshore wind turbines at higher Liquid Water Content (LWC) levels. Four different LWC values were tested for both glaze and rime ice conditions each, to cover the possible spectrum of typical icing conditions. A high-speed imaging camera was used to capture the dynamic ice accretion process, while a Digital Image Projection (DIP) technique was used to perform the 3D qualification of the ice accretion characteristics. Two highly sensitive multi-axis force and moment transducers were used to measure the lift and drag forces acting upon the airfoil. The lift force was found to decrease, and the drag force was found to increase with the formation of ice. The amount of change in the unsteady aerodynamic forces was found to depend on the ambient temperature, the LWC, as well as the accreted ice structure. 
    more » « less
  5. ; ; (, AIAA Journal)
    An experimental study was conducted to compare various strategies for UAV propeller icing mitigation. With a propeller model with an untreated hydrophilic blade as the comparison baseline, three icing protection systems (IPSs) were evaluated systematically: 1) a passive method with the propeller blade coated with a super-hydrophobic surface (SHS) coating; 2) an active IPS design to forcefully heat the entire blade surface; and 3) a hybrid IPS design with only limited surface heating along the blade leading edge and the SHS-coated blade. While the passive method with the SHS-coated blade was found to be only marginally effective under the glaze icing condition, it became ineffective or even further deteriorated the propeller performance under the mixed and rime icing conditions. While the active IPS design to forcefully heat the entire blade surface was found to be able to prevent ice accretion on most of the blade surface, some minor “ice crowns” were still observed to accrete near the blade tip. The hybrid IPS design was demonstrated to keep the entire blade surface ice-free under all the icing conditions with substantially less power consumption (i.e., [Formula: see text] power saving), rendering it a compelling UAV propeller icing mitigation strategy. 
    more » « less
  • Citation Formats
  • MLA
  • APA
  • Chicago
  • BibTeX
  • Save / Share this Record
  • Send to Email